Download - Amoco - Directional Survey Handbook
UpstreamTechnology
Group
ISSUE 1SEPTEMBER 1999
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 i
Contents
Authorisation for Issue
Preface
Amendment Summary
Section 1 Introduction1.1 About this Handbook
1.2 Directional Survey and Value Addition
1.3 The Design-Execute Principle
Section 2 Policy and Standards2.1 Drilling and Well Operations Policy
2.2 Policy Expectations
2.3 Standard Practices
Section 3 Theory3.1 Surface Positioning
3.2 The Earth’s Magnetic Field
3.3 Position Uncertainty
3.4 Position Uncertainty Calculations
Section 4 Methods4.1 Multi-Well Development Planning
4.2 Survey Program Design
4.3 Anti-Collision – Recommended Practice
4.4 Anti-Collision – Selected Topics
4.5 Target Analysis
4.6 Survey Calculation
4.7 In-Hole Referencing
4.8 In-Field Referencing
4.9 Drill-String Magnetic Interference
4.10 Survey Data Comparison
BP AmocoBPA-D-004 Directional Survey Handbook
ii Introduction September 1999 Issue 1
Contents (cont’d)
Section 5 Survey Tools5.1 Inclination Only Tools
5.2 Measurement While Drilling (MWD)
5.3 Electronic Magnetic Multishots
5.4 North-Seeking and Inertial Gyros
5.5 Camera-Based Magnetic Tools
5.6 Surface Read-Out Gyros
5.7 Dipmeters
5.8 Obsolete and Seldom Used Tools
5.9 Depth Measurement
5.10 JORPs
Section 6 Technical Integrity
6.1 What is Technical Integrity ?
6.2 Risk Assessment
6.3 Surface Positioning
6.4 The Directional Design
6.5 Executing the Design
6.6 Survey Data Management
6.7 Performance Review
Appendix A Mathematical Reference
Appendix B Approved Tool Error Models
Appendix C Data and Work Sheets
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 v/vi
Preface
This Issue 1 of the BP Amoco Directional Survey Handbook (BPA-D-004)is applicable in all areas of the BP Amoco organisation.
In addition to the uncontrolled hard copies, this document is alsoavailable online via the wellsONLINE and ASK websites, accessible onthe BP Amoco Intranet. The online document is to be considered themaster version, containing the most up-to-date information.
The distribution of this document is managed by the UpstreamTechnology Group (UTG) and controlled and administered in Aberdeenby ODL.
ODL may be contacted as follows:
UTG DCC or: UTG DCCODL ODL MailboxBuchanan House BP Amoco, Dyce (through internal mail)63 Summer StreetAberdeen AB10 1SJScotland
Tel 44 (0)1224 628007Fax 44 (0)1224 643325
Alternatively, contact the UTG Wells Document Controller,Steve Morrison at BP Amoco, Dyce, Extn 3593 (44 (0)1224 833593
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 vii/viii
Amendment Summary
Issue No Date Description
Issue 1 Sept 1999 First issue of document.
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Introduction 1-i/ii
Section 1
Contents
Page
1-1
1-2
!"# 1-6
Figure
1.1 Well positioning process and associated files 1-7
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Introduction 1-1
Who this Handbook is for, and whatit’s about.
! " # $%
& ' ( )*+(,-% ./ .$ 0+ &
1 $ # # # $ # $ & 1 $*$%) #$"&
$%#&'
1 " "% " &1 ! # #$& 2 " # " $ &
1
Reference toanother sectionin the Handbook
Reference to atechnical paperor publication
Indicates a BPAmoco StandardPractice
BP AmocoBPA-D-004 Directional Survey Handbook
1-2 Introduction September 1999 Issue 1
&#
1 & " 3 " ) % ) ' $ 1% 21/&43 " %) ' $ 1%21/&1 ' &
&#
1%$ " " 5% ' " )+.6'.* $ 7) *$$! 7 $!&
&(#
$$ " $ # # % )' $ 1% 21/& ' $ "$$ $ $43 "% " # 5 & 2 # &
)
# " " % % &
0 " 5 "# $ & 1 $ % " %" &
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Introduction 1-3
*&
0 " # $ # " & #% " 8 # "$ &
(*+& "$$,
The well’s surface position must be directly above or at aknown horizontal offset from the geological target locatedby the seismic survey, often taken months or years before.
1 "#% %$ "" " 3 & ' $ "#% ""% % # 3 $ &0"### # " #$" &0 #$ & . % %" $&
(-(*+& "$$,
The wellbore must be drilled such that it intersects an oftensmall and distant geological feature.
# $$ $ " "% # # # $ & ) " " # & $# $$ % #$ #$ " &1 " # & 9$ $$ " "#% 8 &+"%"$ " $$3&
BP AmocoBPA-D-004 Directional Survey Handbook
1-4 Introduction September 1999 Issue 1
$ " " &' 3 " # $$ $ "# " $ " $&) #$$ " % " "" : #$ " $"" : &)% " "" " &
&$..$,$,&
The wellbore must not hit any existing wells which liebetween it and the target.
" " # ; " 5 $ #% # "& # $ $ # % ' $# "&1 $ "# $%" $ % $& 1 $ "# """ # &
&&
0 $ #! $ 8 : $ " : 5 5& $ 3 $ " " $$ & 1 $ $$$ %$#&" " &
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Introduction 1-5
(* /"*$0*1&$
1 5 # # $ " $ & + $ % "3$ $ $ &1 "0)5<, " $#& ) $ " " #5 % "$$$ 8 "" &
121,0*..,0*$$1
"# $ 5 $# ## & 1 " % $ & ) % "" # % $ " "3 % % $ &' $ & " "" $ $ &
.)
'$$ % # " " #$ $&
1 7$!$%$%$ $ $& 1 # # =
• ' $ " " & $ $ $ $%" 5 $ #$ $$ # #$$
• ' & 4$ $ 1 " # """$3 % 5
BP AmocoBPA-D-004 Directional Survey Handbook
1-6 Introduction September 1999 Issue 1
! "#$
Examining any question or decision about well positioningagainst this principle is almost guaranteed to help in itsresolution.
% & ' # ())* $ ! #
The purposeand content of theDirectional Design
and Well Survey Filesare explained in
Sections 6.4 and 6.6
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Introduction 1-7/8
Identify geological target(s)
Formalise well objectivesand planned surface and
target locations
Design directional planand survey program
Position rig atsurface location
Acquire and validatesurvey data per program
Compile definitive well surveyand load to database
Final WellPosition Memo
Defintivewell survey
Survey reports
Well Survey File
Well LocationMemorandum
Final proposedtrajectory and
survey program
DirectionalDesign File
Well Data Packor similar
Figure 1.1
Well positioningprocess andassociated files
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Policy and Standards 2-i/ii
Section 2
"
Contents
Page
3$#" 2-2
" !# 2-3
" 2-9
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Policy and Standards 2-1
" What BP Amoco Policy says aboutdirectional surveying and what itmeans for your Business Unit.
" "$&17 !7$! "$
## &1"#$ $ &
5 3 " $) + 7 $ !&1 " #&
1 " $ ) 18 "% $ $ $ & $3 # 7 3" $0$!& 13" % 21/ )' $ 1& # $ "" " &15 " $ &
1
BP AmocoBPA-D-004 Directional Survey Handbook
2-2 Policy and Standards September 1999 Issue 1
7 ! 1 & " & 13 "8 " $% % 216&12 1 6 8 "> # " 21/1 &1 4 &?" $&
1 " " % " # 2 3 5 "#&) " # 8 $ % # $ # " #% &
$$ # 3 " 8 " " &' # " $&
3$#
"
1 $ ) + 7!/ " 1$ @ + # " "$&
2 " $ # 2 0$ % " "" / & . % 2 # #
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Policy and Standards 2-3
" " #
5 $$ # GettingHSE Right&
" " %21/)' $ 1%&
" !#
1 $ # $ 3 "
$italics&*3 "# 5 # &
1 " " 5 3 " # % # 5 5&9 5 #%# "3 # & $ " &
(12.5) A database of well trajectories (planned and actual)and all project data (slots, targets, locations andprojections) shall be maintained in a form approved by aqualified person appointed by BP Amoco Senior DrillingManager. This safety-critical database shall be the subjectof a written plan approved by BP Amoco that describes howit shall be managed throughout the Business Unit life cycle.
,&, 1 0$ # $ "=
• )
• ) " $ "
BP AmocoBPA-D-004 Directional Survey Handbook
2-4 Policy and Standards September 1999 Issue 1
• ) " $ "
• 1$ # $$ # 2 "
,&A $ # " " " &
,&? " % 0 6 " 1. / . #"&
,& $ 8 # " " " # % $ &
,&B $ # # $" # % #&
,&- " $ ## $ #& # " &
,&C # " # &
'"
(8.4) The final position of all spud locations shall beconfirmed by a qualified surveyor.
(8.8) The rotary table elevation, relative to seabed at meansea level and water depth (offshore drilling units) or therotary table elevation relative to ground level (land drillingrigs) shall be determined and formally recorded.
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Policy and Standards 2-5
A&, 9$ #% "# # " ) 6 0&
A&A ' " # " 5 $ "5 % " " # &' " " " " &
A&? ) " $ 5 # " $
# Getting HSE Right &
A& 1 " " # # 3" % " % 9) 0&
A&B 1 $ " "## # " #&
A&- 1$; 41*%D* & =
• / $ #
• "" # # %"
BP AmocoBPA-D-004 Directional Survey Handbook
2-6 Policy and Standards September 1999 Issue 1
")
(12.1) Survey programs for all wellbores shall be designedsuch that the wellbore is known with sufficient accuracy to:
a) Meet local government regulations
b) Penetrate the geological target(s) set in the well’sobjectives
c) Minimise the risk of intersection with any nearbywellbore
d) Drill a relief well
(12.2) The performance specification of all instrumentsemployed on operations shall be approved for the use by aqualified person appointed by BP Amoco Senior DrillingManager.
?&, 1 $ $# $ $8 &
?&A + " # $&
?&? 1 $ $ # "" &
?& ) #$$ &
?&B $ $ $ # " $$ $$ &
?&- !1$ # # #"# &
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Policy and Standards 2-7
?&C ' $ " $ " " #&1 # "# $ $;% "=
• 1# ""#$$
• 1 " $
• 1 " $ #! $ $ "
?&E 1 $ # "" " " & " ! F + $ 4 $F+4&
4 &
(12.6) On multi-well operations a collision check shall beperformed on the planned well trajectory
(12.7) All procedures for assessing tolerable risks ofcollision, defining minimum well separations and ensuringcompliance with such criteria while drilling shall beapproved by a qualified person appointed by BP AmocoSenior Drilling Manager.
9 5 " $ &?&9 % 3 " &?# # &
&, $## $&
&A # " # 8 # " $ " "&
JORPs arediscussed inSection 5.10
BP AmocoBPA-D-004 Directional Survey Handbook
2-8 Policy and Standards September 1999 Issue 1
&? 1# "## $ &
& *# # " $ 080& # 08 " # # $" & ' 0 " "#$$&
&B 1 # " 08 #=
?σ,GσAGH,GAGSbG&,I,
?σ,GσAGH,GAGSbG,J,
#
σ, K # ,&&
σA K ' "$# ,&&
, K ; #
A K $+ "$#
Sb K #"&
K &
&- 1 # " ## "=
( )σσ π
22
1
21 2
1 2lnd d
Rd d Sb
+
+ + +
#=
σ K σ σ12
22+
R K 14
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Policy and Standards 2-9
&C 1 1 4 # " " 3" "$ # 2 &
&E $ # $ $ # &
&L * $# $ $&
&, " % " ## $&
&,, ) "" # # &
&,A ' " $ % $ # $ % $ # "" ""&
"
5 " " %# $$ # $& 9 %# "&
,& # # " " # # "
&
A& # # /1. %?&,&
BP AmocoBPA-D-004 Directional Survey Handbook
2-10 Policy and Standards September 1999 Issue 1
?& 0$ # "=
1 " /$ //$ 0//0%?&A%
" "%# # $ '94%&E&
& 1$ # # # ; ; & 7 ! ,A!&&
B& #0 &E&
-& " # $ -&-&
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-i
Section 3
Contents
Page
'" 3-1
51+ 3-17
"( 3-21
4 "(& 3-26
Figure
3.1 The Earth’s surface and the geoid 3-2
3.2 Globall y and locall y fitting ellipsoids 3-3
3.3 Dependence of latitude on choice of ellipsoid and datum 3-3
3.4 Relationship bet ween geodetic heights 3-5
3.5 Geographical, mapping grid and drilling grid co-ordinates 3-7
3.6 Variation of grid scale factor across a mapping grid 3-8
3.7 Components of the magnetic field vector 3-18
3.8 The one dimensional normal distribution 3-23
3.9 A two dimensional distribution resolved in t wo directions 3-24
3.10 Principal directions and the standard error ellipse 3-25
BP AmocoBPA-D-004 Directional Survey Handbook
3-ii Theory September 1999 Issue 1
Section 3
Contents (cont’d)
Table Page
3.1 Definition of the drilling grid in someBP Amoco operation areas 3-9
3.2 The magnetic field in some of BP Amoco’s operating areas(approximate values as of 1 Jul y 1999) 3-19
3.3 Confidence intervals for the one dimensionalnormal distribution 3-23
3.4 Confidence intervals for the t wo dimensionalnormal distribution 3-25
3.5 Error term propagation modes 3-27
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-1
An introduction to the science of wellsurveying.
# # $"#&' 5
8 % $ " "" % %$ " &
'"
$ "6$ # # ! 5 """" $&1$ $ " " %21/M 1%&
)0
0 $, .."$
1 * ! " $ % $ " $&0 % $ $% 3 " $ &1# &
1
BP AmocoBPA-D-004 Directional Survey Handbook
3-2 Theory September 1999 Issue 1
Ocean
The Earth
Mountain Range
Geoid
1 $ $ 5 * ! " : & / # " "7 !" ;85K7! " $ K 7,>"!& 1 % " # "&1 8" &
1 # " &6" $ " # $ " * !"&5 !,E-- # $ . & 1,E--$ " # $ 0! 4 D% $ .AC$ " &1"$ % " 5 % $"" $ &
/ " $ 5 $ # * % " &)/E $$ " $$" $ )/E# $ & ' / $ /&
Figure 3.1
The Earth’s surfaceand the geoid
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-3
geoidglobally fittingellipsoid
eg. WGS 84
locally fittingellipsoid
eg. Clarke 1866
area of bestfit of ellipsoid
to geoid
1 $ " * $$ " & '" $ $%# $ " & 1 $ " 3& 1 $% #3 # $ &
blacklatitude
greylatitudeEQUATOR
grey ellipsoid Point
perpendicular to grey ellipsoid
black ellipsoid perpendicular toblack ellipsoid
Figure 3.2
Globally and locallyfitting ellipsoids
Figure 3.3
Dependence oflatitude on choice ofellipsoid and datum
BP AmocoBPA-D-004 Directional Survey Handbook
3-4 Theory September 1999 Issue 1
5 % "#$ " =
6 & B°!A&--,N. 6 & B°!AA&CA?N.
6$& ,°BL!?&A,?N) 6$& ,°BL!E&AL,N)+/,L?-$ )/E$
,E? )/E
. )/E " &
0, 0* + * ,&
1$ " * !"% "$$ % "
!" & $& 1 $ $ " $ & 1 ##&
+%$ $ # 5 $ # & $ + %.# +. O 2DP . @ " ,LEE.@EEO 2P&
' % ## 5 " &1 " $ 6# 161 06#) $ 06)& * "" " $ 61 " $ & 1 $ $& $$# $ % $ 5"# 5 $&2" $ # $&4$ " 0 6 $ # $ & $ &
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-5
$ $" & 1 $ 5 / # %$$ )/ E & ' $ $ " / % " $ Q$ $ N " & /$ " & 0/ $ $$ &#%$5 / & &
geoid height(N)
ellipsoidalheight (H)
gravity-relatedheight (h)
H = h + N
Ellipsoid
Geoid
1##0
$ "$ # ; % $$ $ " " & " " $ # #&1 * !" " $ 3 " " $$ $ $ & 1 " $% $ "
Figure 3.4
Relationship betweengeodetic heights
BP AmocoBPA-D-004 Directional Survey Handbook
3-6 Theory September 1999 Issue 1
$ &) " % 8 $ " # # & 8 $ "# 8 # 8 % " 5 ED50 / UTM zone 31N . Nord Sahara1959 / UTM zone 31N $& . $ $ " 8 $&210;?, $: $ "&
" "% " # & 1 8 % $ " & 1 8 " 1 0 6 "% # " &+ """ &
8 &/% 8 # $$$ & % $&1 $ $ 3 " # 8 8 &93 " % $& $ ; 210 210 20 "# $&1210 $ " 8 % - -$"$ &1 10 8 # ""$ $$ & ; 5 /%4 &
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-7
Central Meridian
drilling grid lines of latitiudeand longitude
mapping grid
Cross-sectionshown infigure 3.6
West of theCentral Meridian, grid convergence
is negative
East of theCentral Meridian, grid convergence
is positive
& '# . & ' " " 3 $ " 3 &. $$ ; " # &
( '#" " $$ & ' " " 3 " 3 & / &1$" $ " & ' #% $ $ #$ # " &1
# ?° G?°& $ "" "" %# "&,° $ &
'" $ % $ $ # $ """ " $&1"%
When survey measurements are related to grid north it isessential that the relevant map grid (projected co-ordinatesystem, including geodetic datum) is identified.
Figure 3.5
Geographical,mapping gridand drilling gridco-ordinates
BP AmocoBPA-D-004 Directional Survey Handbook
3-8 Theory September 1999 Issue 1
1 8 $$ " # "$ " $ $ $& 1 " " #&LLL ,&,&' " "% $$ &
Central Meridian
grid scale factor < 1
mapping projectionEarth’s Surface (Spheroid)
grid scale factor > 1
0
$ $ $ " #%; " $$ &1" # %""# #=
• 1 K #" $ " 5" $$&' " # $ $$$&)$ % 8 "
• 1 $ $ $ " " $$& ' $$ $ # "
Figure 3.6
Variation of grid scalefactor across a
mapping grid
BP AmocoStandard Practice
BP AmocoStandard Practice
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-9
3 " % " " " $$# & "#$ #%""" " &
structureref. point
drilling grid north(DGN)
Structure Centred Referencing Survey Reference = True Northdrilling datum
(= rotary table)A
Well Centred Referencing Survey Reference = True North
DGN
B
Structure Centred Referencing Survey Reference = Grid NorthC DGN
Well Centred Referencing Survey Reference = Grid NorthD
DGN
(MAPPING)GRID
NORTH
TRUENORTH Norway
UK - FortiesUK - MagnusUK - former Amoco
UK - former BP (excluding Forties, Magnus)Netherlands
USA - Gulf CoastUSA - LandColombia
USA - Alaska
Table 3.1
Definition of thedrilling grid in someBP Amoco operatingareas
BP AmocoBPA-D-004 Directional Survey Handbook
3-10 Theory September 1999 Issue 1
*..,00** &$11 ,$,
1 # " $ / " $ " " $ " # $& 9 # % "#$ =
Survey Reference Direction• 1. .#
• /. " #
Drilling Grid Origin• ) "$
• "$ " #
0 ")
1 / $ % /% " "" $ $ " $ " # & ' $ " " $$ 8 # /&
/ " AC $ A% $ " & " " 3 "/& . "% &1 " "5& " / $ &
/ # $ $ ""2 / $ $ # &1 "
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-11
$ / 5 R, R? " & $ $# &
++ * ,.0"60"7
"" / $# /&* /$ $/ # 7"! & 1 # # " &1 "/& 1/ " /"#&
1 "" / 3 & " % & / $R,B " % " " % " $ " /&
$ *0" &,8(
3 $ / $ $ 3 $ &1 3 % 3"#" $&
1 / 3 #
)%&* ( &1 / " $ " RAB R,A & /$ 3"41D " " ,A5&
BP AmocoBPA-D-004 Directional Survey Handbook
3-12 Theory September 1999 Issue 1
1 4 # (% /& ' / # " $ & 3 " />/&
/ # &&1 3 "# &1""
# 1 ±,? &
. $,1 (* 1 ,
/ $ ; &9 $""% / " $ " % $ # &+% / & ' 5 " "; RA, "/& / $ )/ E $ $ & 3" &
$'")
" $ # / "& " / & ,LL " $ # " "" $&" & 1 # $ $"" & $ & #& 6$$ 0; $&1 $ $ % +,& $/ " % /
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-13
# $ & 1 # $ " "#&
# "/ " $ #" # & 1 $ " " ## &) ""5 % & F2 $ $ "5 8 8 & 1 $ &
+% # $ % # $ $& 2 / " " $ # "$/&
(%"
2# $ $ 3& 4$ # $ " # & 1 " $ # # " $ " & 1 #$ $"# %"" % # $ " " & 1 #"" $ "$ S$66 26 &
BP AmocoBPA-D-004 Directional Survey Handbook
3-14 Theory September 1999 Issue 1
.$,0- ., &$(&6.-.7
1 66 $ " $ $ $ # " # "% $ /& " #" 5 $# " &
) "" % $ $ # &1 4+@% $% " # % $&/%$ & '" " $ " $ 3&
" $ " $ " " "3& *5 $"3 $" R&BA% 5$$" B&6#"3 $" , # " RAB& + # 5 & " $ & '" $% " $" "" % $" $& " # /%# "&
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-15
(.*$*- ., &$(&6(-.7
126 " $ &1 "5 " " & 4$ 66 "" $ $ &
1 3 $ $% " $ # " & 26 $ # % "& 1 &
1 26 # &1 $" " # &1$ $" "> > $" & 1 " 26 $ $ " &'" # : &BT " # & '" $ 26 3% 26 " # & $ "$ 21/M 1&
## -%6% 26 5 &
BP AmocoBPA-D-004 Directional Survey Handbook
3-16 Theory September 1999 Issue 1
&.-*$,
&66 $ " &266 " $ "$% & " $ "# " $ &
3"(
0 " $/& / ",B A & 1 ; " / & 1# $ ; "" # / " " $ & "" $ " "" & 0 " " "" &
1 " " $ % $ " % % $ & +#" #
"±B, %$±AB &1 " ## $ # &
9 # #% $ # " # "" # & 1 ; " #$ "" 3 "#&' "" $ 3&
Section 3.3explains the statistical
concepts behindposition uncertainty
Section 4.2 givesthe surveying
requirements for reliefwell contingency
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-17
) "" " #3 # =
• 1 # % " & 1 "8 " "
• 0" & 1 " $ "5# $" "" "
1 3 " " " # $ & $ 3 % 3 " % 3 $ & 1 $" & " " $" # & 9 5 " % 21/ M 1&
51+
1* !$ " " %" # &' "
• .%D δ% " $ # " ; 8 " $ " % #% $ " #
BP AmocoBPA-D-004 Directional Survey Handbook
3-18 Theory September 1999 Issue 1
• . % I Θ% " $ " ; $ " % ##
• / % F B% # " $ " "
1 $ " % &1 X%YZ&
HX
Θ
F
δ
Y
Z
True North
1 ' " $ "5 1& * ! $ " #% & &" K,1&
Figure 3.7
Components of themagnetic field vector
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-19
1"#$ $ 5 " $ ""!8 $&1 $ " ; " % # $"" "$ $&
Location Lat. Long. Declination DipAngle
FieldIntensity
HorizontalIntensity
Vietnam 8°N 109°E 0° 0° 41,000 nT 41,000 nT
Abu Dhabi 24°N 54°E 1°E 36° 43,000 nT 34,000 nT
Egypt 28°N 33°E 3°E 41° 42,000 nT 32,000 nT
Kuwait 29°N 48°E 3°E 44° 44,000 nT 32,000 nT
Algeria 29°N 1°E 2°W 39° 40,000 nT 31,000 nT
Trinidad 10°N 61°W 14°W 34° 34,000 nT 28,000 nT
Colombia 5°N 73°W 6°W 31° 33,000 nT 28,000 nT
Azerbaijan 40°N 50°E 5°E 58° 49,000 nT 26,000 nT
USA – Gulf Coast 28°N 88°W 0° 59° 48,000 nT 25,000 nT
Bolivia 17°S 62°W 9°W -11° 24,000 nT 23,000 nT
Argentina – Austral 54°S 66°W 12°E -50° 32,000 nT 21,000 nT
UK – Wytch Farm 50°N 2°W 4°W 65° 48,000 nT 20,000 nT
UK – Central N. Sea 57°N 1°E 4°W 71° 50,000 nT 17,000 nT
Canada – Alberta 55°N 114°W 20°E 77° 59,000 nT 13,000 nT
Norwegian Sea 65°N 7°E 2°W 75° 52,000 nT 13,000 nT
USA – Alaska 70°N 147°W 29°E 81° 57,000 nT 9,000 nT
0)+
. * ! "% $ " 5 " =
1,+ .
1 " $ * ! " 5 LET " " $ * !"& $ ## & ' . % " $ " 1 "$ &
Table 3.2
The magnetic field insome of BP Amoco’soperating areas(approximate valuesas of 1 July 1999)
BP AmocoBPA-D-004 Directional Survey Handbook
3-20 Theory September 1999 Issue 1
01 &! /2!.
1 " &9 $ $$& 6 " # & 1 " %# " "#1&
. &1'02 /2!.
1 " "#$ $ % $& ' " " &$$ % " ""# 1 . % %$ "$$ &
1"" "$ $ " B&A"" $$""$&E&
0)1
$ %" % " &1 " "# " : " " $&' /$ / /$ 0 (( " $ " $ "% & 1//0 / " " & '/49' /$ 4"9% B % ! &
BP AmocoStandard Practice
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-21
"(
$ "# & 1 " # "$ # % " &
1 " # % % 3 &#%# # &95 %
• ) $ ; # % " # " &1
• ) $ $ $ & " $ % " # " $ " & 1 #
" $% # &
($)
9 % #" =
1 &&σ%$" " 3 " $ 3"" # & 1 " " # $ #",&C,&. " " -ET " : " &
BP AmocoBPA-D-004 Directional Survey Handbook
3-22 Theory September 1999 Issue 1
'" #(U$ % O(%UP3
&5 %OBV?W%-VBWP$ LBT" " 2& ' "5" "
" "& 1 Oσ%GσP OAσ%GAσP # "$ ?&E& 1 ,$A$,A" &1 " # & ' " $ % " -B&TL-&-T&
$, 1 ,$,.,$*1.*-($,
9 $ % / " &1 # µ σ 2 " σ " =
f x( ) =1
σ 2πexp
− x − µ( )2
2σ 2
1 "#$ "$ # , $ A $" " &1 -E&?T LB&T " # " # &
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-23
-3.0
0.05
0.1
0.15
0.2
0.4
0.35
0.3
0.25
0
x
-2 σ +2 σ-1 σ +1 σ
95.4%confidence
interval
68.3%confidence
interval
-2.0 -1.5-2.5 -1.0 -0.5 0.0 +0.5 +1.0 +1.5 +2.0 +2.5 +3.0
f(x)
LBT " " # % 3 A $ & 1"? $ # % 5 "$T# 5 &BT" $ $ &' #% 3 7G>A$ K LBT "! 3 5 &+ " " =
confidencelevel
standarddeviations
confidencelevel
standarddeviations
confidencelevel
standarddeviations
25% ± 0.32 80% ± 1.28 95% ± 1.96
50% ± 0.68 85% ± 1.44 98% ± 2.33
75% ± 1.15 90% ± 1.65 99% ± 2.58
Figure 3.8
The one dimensionalnormal distribution
Table 3.3
Confidence intervalsfor the onedimensional normaldistribution
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-23
-3.0
0.05
0.1
0.15
0.2
0.4
0.35
0.3
0.25
0
x
-2 σ +2 σ-1 σ +1 σ
95.4%confidence
interval
68.3%confidence
interval
-2.0 -1.5-2.5 -1.0 -0.5 0.0 +0.5 +1.0 +1.5 +2.0 +2.5 +3.0
f(x)
LBT " " # % 3 A $ & 1"? $ # % 5 "$T# 5 &BT" $ $ &' #% 3 7G>A$ K LBT "! 3 5 &+ " " =
confidencelevel
standarddeviations
confidencelevel
standarddeviations
confidencelevel
standarddeviations
25% ± 0.32 80% ± 1.28 95% ± 1.96
50% ± 0.68 85% ± 1.44 98% ± 2.33
75% ± 1.15 90% ± 1.65 99% ± 2.58
Figure 3.8
The one dimensionalnormal distribution
Table 3.3
Confidence intervalsfor the onedimensional normaldistribution
BP AmocoBPA-D-004 Directional Survey Handbook
3-24 Theory September 1999 Issue 1
(%)
9$?&L "# ; $ % $ "" # &$ " % # $" $ &' "$% " . * &
North
East
% # # " 5 & ' # # &1 # 5 # 3$ " $ ,$ " &1# "#$"$&
Figure 3.9
A two dimensionaldistribution resolved
in two directions
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-25
directionof maximum
variation
directionof minimumvariation
σmin
σmax
standarderrorellipse
North
East
90
' # " % " # " & 9 " # %# "& 9 %"$""$"" " & 9 5 % A&B $ % # 5 3 A&Bσmax
A&Bσmin % LBT " $ " &+ =
confidencelevel
standarddeviations
confidencelevel
standarddeviations
confidencelevel
standarddeviations
25% 0.76 75% 1.67 95% 2.45
39.3% 1.00 86.5% 2.00 98.9% 3.00
50% 1.18 90% 2.15 99% 3.03
Figure 3.10
Principal directionsand the standarderror ellipse
Section A.2includes more detailson the mathematics ofposition uncertainty,including how tocalculate other valuesfor Table 3.4.
Table 3.4
Confidenceintervals for the twodimensional normaldistribution
BP AmocoBPA-D-004 Directional Survey Handbook
3-26 Theory September 1999 Issue 1
4 "(
&
1 # # #&' %$"# $ &A " # "3$ &1 # # $ " " # &
" " &#% " $ " &
)#
1 " "$ =
• * # #
• " $ % ;
• * " ""
• 1 # ; " $ $ #
• 1 "" # " 3 " ""
For a fulldescription of the
method, see
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-27
'
# & "" " &' " "#$ =
• %$&7 !
• #$ $ " % $ "" "
• ;%5 "
• $ 3
• "" ρ,%ρA ρ?$ # % #% "
1 "" ! : # !"" # #&1" =
PropagationMode
ρ1 ρ2 ρ3 mean
Random 0 0 0 0 Systematic 1 0 0 0 Per-Well 1 1 0 0 Global 1 1 1 0 Bias 1 1 1 ≠0
" # " $" $" #"" &
Table 3.5
Error termpropagation modes
Appendix Bcontains a list of thecurrent BP Amocoapproved errormodels.
BP AmocoBPA-D-004 Directional Survey Handbook
3-28 Theory September 1999 Issue 1
&"
" 3 "#$ =
• " : $$ $ "
• # 8 % & "
• # " 8 $% $
• "
@ , && "
& 1
$ " $ &1"
" %
?×? 5% &
-
0 3 $ %# " ;& # $ "# # & &
%" % 5&"# ;% $ $ % & *5 5 $ " # ; " ; # $ &1 $ " # % % $ " % # %% $ "5 " &
Section A.2describes the
interpretation andmanipulation of
position covariancematrices.
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Theory 3-29/30
1"" " " # # " # & 1 "#$"" =
• * #
• ! $ # $$ $
• + $ %$ "$#
#
1 ## " #=
• 1 " # & ' $ $ !
• 1 # # $ $ & ' $ $ !
• 1 "" $ #% " % "
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-i
Section 4
1
Contents
Page
4 13#)" 4-1
4 ") 4-6
4 &9*))" 4-17
44 &9# 4-27
4: 4-34
4; & 4-39
4< *' 4-40
4= +*' 4-48
4> 1' 4-55
4? &)# 4-59
Figure
4.1 A well planned development 4-3
4.2 A poorl y planned development 4-5
4.3 Flowchart for surve y program design 4-7
4.4 Schematic of a relief well 4-10
BP AmocoBPA-D-004 Directional Survey Handbook
4-ii Methods September 1999 Issue 1
Section 4
1
Contents (cont’d)
Figure Page
4.5 The minimum separation rule for major risk wells 4-18
4.6 How a nearb y offset well appears on a travelling c ylinder 4-27
4.7 Travelling c ylinder co-ordinates 4-29
4.8 Rules and conventions for drafting tolerance lines 4-30
4.9 Principle of single wire magnetic ranging 4-32
4.10 Calculation of the driller’s target 4-35
4.11 Calculation of the driller’s target (contd.) 4-36
4.12 Effect of hole angle on size of driller’s target (side-on vie w) 4-37
4.13 Driller’s target volume for a horizontal well 4-38
4.14 Pinched-out driller’s target – a case for geosteering 4-39
4.15 In-hole referencing – section drilled with multiple BH As 4-42
4.16 In-hole referencing – section drilled with single BHA 4-45
4.17 The IIFR principle 4-48
4.18 Typical process sequence in an IIFR operation 4-51
4.19 Typical data flow in an IIFR operation 4-54
4.20 Estimating magnetic axial interference 4-56
4.21 The principle of simple axial interference corrections 4-57
4.22 A Surve y T-Plot 4-60
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-iii/iv
Section 4
1
Contents (cont’d)
Table Page
4.1 Required competencies for anti-collision work 4-19
4.2 Calculation of in-hole reference corrections –section drilled with multiple BH As 4-44
4.3 Calculation of in-hole reference corrections –section drilled with a single BHA 4-46
4.4 Maximum acceptable axial magnetic interferencecorrections, b y region 4-58
4.5 Forbidden hole directions for axial magnetic interferencecorrections 4-58
4.6 Rules-of-thumb when using the error ellipse method 4-61
4.7 Quantitati ve interpretation of the error ellipse method 4-62
4.8 Example of a Relative Instrument Performanceanalysis for azimuth differences 4-64
4.9 Rules-of-thumb for use with Relative InstrumentPerformance anal yses 4-65
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-1
4 1 Mathematical, logical and proceduraltools for optimum well positioning.
$ $$ "# $& 0 " %
" " " " # % 5&
"0@
1 5 " % %$ & A " 5 % " 5 # # $&
4 13#)"
1
$ " # $ " #% $ *$ " # " " # # %$ &*$ "" 3 $& 1 3 " $ "## " & 1 "# " " $&
1
BP AmocoBPA-D-004 Directional Survey Handbook
4-2 Methods September 1999 Issue 1
1 # $ $ $ $ #% " $ % " &) "$ % "5 $ # $ & & 1 " $ $ "$ &
&1'"
*" 3 # =
• *5 $" %$#
• /$ $
• 1 "$ $
• # " % $ # $ $
• $ 3% # " "
1# $ =
• $% #$ $ $ %# $3"
• #$ "
• $ #$ "# 8
1 $% # # " & " &" 5 " # %
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-3
&1# #"$"" $" &
*" " " & 1 "# " #" # $## "5"$&#%
# - 4
/ .
1 # # " % # #" &
0''"
1 " " $ $ 5 "5 &
9$&, #7 !"" # &
Slot in use or planned for use
Spare slot
Well location at fixed depth(say 500 ft bMSL)
Drilled well path
Planned well path
A-1
A-2
A-3A-4
A-5
A-6
A-8
A-7
A-9
Figure 4.1
A well planneddevelopment
BP AmocoBPA-D-004 Directional Survey Handbook
4-4 Methods September 1999 Issue 1
1 5 "#$ =
• " &) % 7 !% " & 1 " #5 $#
• ) " %$ # "
• &1$5"5 " $ $ "
• ."$ # #" % $ 5 #
• . " $ % " $ &1 "#
• . $ " % $ " & $% # 5
• # "8 & 1 $
" # # $ > $ % $ 8 =
• $ >"" $$& $ #$# " " $
• 1 # " ""$ % % #"
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-5
• 1 " "
• / 8 # " "#$"
#" % "$ &A # # %# $ "#&
slot in use or planned for use
spare slot
well location at fixed depth(say 500 ft bMSL)
drilled well path
planned well path
A-1A-5
A-4
A-3
A-2
1$ $#%$ # $ 3" " #& % $ " $ ""& ) " % "" &
#+%"
+ # # "" % $*$%) "# &
Figure 4.2
A poorly planneddevelopment
BP AmocoBPA-D-004 Directional Survey Handbook
4-6 Methods September 1999 Issue 1
It may be necessary to incur extra cost to avoid the paths ofwells that have yet to be drilled, or to survey the top-holesections of wells more accurately than would be needed werethe well being drilled in isolation.
#"&
4 ")
3#)@
1 $ " # 3 " 3 $ " $ &" " $#=
• / "" # # #! $8
• "" 3
• 3 >
1 $ " #$ -
#
& % " $ & 1 $ $ & ' % $ =
,& 1 &
A& %# "&
?& 4$ "$ $% # &
& $ &
B& &
-& $ %"&
C& $" "&
Appendix Ccontains a Survey
Program Data Sheet,useful for inclusion in
the drilling program
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-7
' $ $ $ F+4 5 # " # $&
"
1 " $ $ 7" 8 % % 8 # !&9$&? # &
identify geological objectivestarget tolerances while drillingmaximum uncertainty ofdefinitive survey
selectsurvey
sequence
identify drilling objectivesanti-collision, economic target sizeexternal magnetic interferencerelief well contingencyregulatory requirements
approvederror models
checkobjectives are met
check operationalimpact / economicsadherence to “lessons learned”survey equipment suitabilityfor well conditionssurvey equipment availabilityimpact on drilling process(stationary pipe etc.)best use made of market placeminimum cost solution
check programrobustnesssufficient data redundancycontingency for tool failure
record indrilling
program
well trajectory,casing program
specify programdetailsstation intervalsminimum depth rangesvalidation surveyscontingency surveys
standardrunning
procedures
JORPs arecovered inSection 5.10
Figure 4.3
Flowchart for surveyprogram design
BP AmocoBPA-D-004 Directional Survey Handbook
4-8 Methods September 1999 Issue 1
$$ $ -$
" # " $ $&1 # 5 " 8 $ $ $ % & 8 $&
*'3&
$"# "# 3 $ $ # $ & 1 # "" & ' " $ # &
1 "#$ $ # "# " $ $;& 9 5 #% " " " 3 " # # " $$=
• ' # " "
• 4 $# % #
• " $ 8 % $
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-9
*..,0,"$$,,0* . +3 ..
. # " # % $ $ =
,& 1" " $ ## &#% "" #% # #$# &' %# $ " $ &' "$# " $ # " # & ' " $ " $ " "##" $ #&
A& " $ " $ ##55 &1# " # & 1# 3 " " #&
?& 1"## 7 ! : " $ $ ""# $ & ' % # $ # $% # # # $$ : # # $ $$ " $ #:# "&15$" " % %" " % $ 5 $ $ ," ? &
BP AmocoBPA-D-004 Directional Survey Handbook
4-10 Methods September 1999 Issue 1
& 1 " " $ # $ " % # "" ;& 1 # # " 5 5 " & $ " &
last casing shoeabove reservoir
first approach- above lastcasing shoe
second approach- at kill point
“cone of uncertainty”around target well
Relief well
Target w
ell
B& 1 "## # &'" $ #% # $ # #$$& '" # # % " 3 " % " # # % % &
Figure 4.4
Schematic of arelief well
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-11
3 .."$$,,0* 8(* 1 ,
1 "#$ # 5 " " 3 " # $ & 1 $ " # $ 3 #&) % )1 "8 " &1 " # 5 #&
,& 9 # $;% $ " $ ? ," A & 1 "=
2σ Absolute Uncertainty = √ [ (2σ surface uncertainty)²
+ (2σ surface-to-seabed uncertainty)²
+(2σ lateral wellbore uncertainty)² ]
Example: Offshore well in 800m of water.2σ surface uncertainty = 5m (typical of DGPS)2σ surface-to-seabed unc. = 8m*2σ lateral wellbore unc. = 10m2σ Absolute Uncertainty = √[ 5² + 8² + 10² ] = 13.7m
* See Section 3.1 for a discussion of USBL acoustic position uncertainty.
Land and hydrographic surveyors will usually quote uncertainties at 2standard deviations (2σ) by default. Check. In some high step-outdevelopment wells, the above criterion may not be practically achievable. Adispensation may be justified on several grounds:
• Knowledge and/or depletion of the reservoir makes a blowout veryunlikely
• Wellbore uncertainty is substantially less in the high-side direction thatin the lateral direction (this fact could be used by careful planning of therelief well)
• The type of survey data to be acquired is amenable to further processingand accuracy improvement, should it be necessary. IIFR is an example
• There is no practical means of improving the accuracy of the surveyprogram
BP AmocoBPA-D-004 Directional Survey Handbook
4-12 Methods September 1999 Issue 1
A& ' # $ ;% $3 $ 3"; & 1 $0) % $ $ $ # $ &
Camera-based magnetic surveys are not adequate for this purpose, exceptover short depth intervals (c. 300m or 1000ft).
?& 9""#"" $% " ; "" # " "5& 1 "" 3 ,&' "" ; " " # # $ 3 5&
There are a number of ways in which limits on the departure from verticalitymay be determined. Measuring the well inclination in the water column,probably with MWD, is among the simplest. Use of LBL acoustics isprobably the most accurate (but also the most expensive).
!1'
0$ $ $ " & ' $% " =
,& 1$$ "& 1 "# $ & 3 ""$&C " &
A& $ ""& $ "% $ " "$ $ $&L&
LBL acousticsare described in
Section 3.1
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-13
?& *5 " "& $ " $##&' $ " % " "" & 1 $ $ $ ; # "5 "&
*..,0$($+&,0$
$ % $ " #$ $" $% " $ % " 8 $!$ &*5 # $ ; - A" " $ & / $% " " & 5 # # $ &$ # $" "" #1@& ' % % $; "&
*..,0$($+&.( *$*&,03,$3
1 #8 $ $$" "" $ ; " & '$% $ 5 " # ?" L " $% " # B" ,B&
9 $ % $ $ $ " "&5 #$ "% =
• 1 "" # ?" % #
• 1 " #
BP AmocoBPA-D-004 Directional Survey Handbook
4-14 Methods September 1999 Issue 1
• $ $ 5 & 1 "
10, &, *+ * ,& &,
1 5 " # 5 $ " " 5 " $% % $ " : "" " #& 1" $ " $$#&1# $ "$ $&1 " " #"#=
,& " $ " 5 $ #
,%XN $ # "& #5" """ #&
A& $ % d% # #%
" "" #%S1(di)S2(di),…SN(di).
?& %d% 4 " $$ $=
( )( ) ( ) ( )
S dS d S d S d
equiv i
i i N i
= + + +
−1 1 1
12
22 2
1
2
...
This formula is based on the simplistic but useful assumptions that (a) theinterfering field from each casing string is equal in intensity (b) the intensitydecreases with the square of the distance from the casing.
& 3 $ # #&
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-15
*..,0*$(,+
1"$ "#$" $$ " % "" # &1 " $ # # " " $ $ $ " &
"(''
1 # "$$ $ =
• # #
• 1 # " " #
1 " " 1$ &B&1%# $ "" 3 %" " $% 3 % & . % /$ # " # $ & 1 $ $ $ 3 % " $ "8 " #&
**A)'
1 3 " # $ # $ $ 3 3 % " "" & # 5 % # "" " "" 3 &. % # $ # " %$ " " 3 "# $ $% ""&
BP AmocoBPA-D-004 Directional Survey Handbook
4-16 Methods September 1999 Issue 1
*
1 " $# "8 "$" $ &1 $ & 1 " " 3 F+4 $$ % "" &
1 #" "3 $ " " "" & ' % " %# " % # " "" " #&' " $$ =
the amount of corroborative data in the form of check shots,multiple probe runs and the like must be sufficient at everystage to confirm the performance of each instrument run inthe hole.
The preciseinterpretation of this
rule for MWD surveysis described in
Section 5.2
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-17
4 &9*))
"
1 " " 4 "%# # 2 5 & 0 $" $ " 7 1 !&&
-
1 4 " 7( 4 !% # # " ( & $" $ #&
1 4 # # # #" ,LL-% # " " # ! . %"$ ##& 1 " $" &
&,0 +*$1-"2* &$11 , "*$& (*
$ # ( 4 "# 5 "" =
,& 0 :084)
+(=
KA&BEσ,GσAGY&,B%,BZGSb
+./=
Kσ,GσAGd,G dAGSb
.#=
K?σ,GσAGHd,G dAGY&,%,ZGSb
BP AmocoBPA-D-004 Directional Survey Handbook
4-18 Methods September 1999 Issue 1
#
σ, K # ,
&
σA K ' "$ # ,
& 1 " " "" #&
, K ; #&
A K $+ "$#&
Sb K #"&
1 # "% % "" &
lesser of :a) 1% of drilled depthb) 10m
radius ofinterfering well
radius ofplanned well
most likely positionof planned well3 σ error ellipse
3 σ error ellipse
most likely positionof interfering well
MINIMUM ALLOWABLE SEPARATION
Figure 4.5
The minimumseparation rule for
major risk wells
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-19
A& 0 :04)
1 ( $ $ " $ % " #& 1 # 4 # " "$ % $ $ 14"#&
0*A)
$ # " &
Specifically, the following personnel must have been assessed by a directionalspecialist as competent in the following skills:
Performinganti-collisioncalculations
Draftinganti-collisiondiagrams
Using the anti-collisiondiagram for decisionmaking while drilling
Well Planners
Person responsiblefor ‘signing-off’ wellsitedrawings
Directional Drillers andDD Co-ordinators
BPA Personresponsible for‘drill ahead’ decisions
)# " % ## # &
$ # # $&
" # 3 M 4 M4 " $"" 216&
Table 4.1
Requiredcompetencies foranti-collision work
BP AmocoBPA-D-004 Directional Survey Handbook
4-20 Methods September 1999 Issue 1
'
" # " 8 &
1 # " " # " # # " 8 &
1" # ""$ # &
&
# " # 8 # " $ " "&
For a database to be used for the definitive clearance scan, there must be aprocess in place which ensures that it is, for practical purposes, identical to thedefinitive drilling database. It need only contain a subset of the wells in thedefinitive database, but must at least contain all the wells known to have beendrilled in the area of interest.
1))#&
1# "## $ $ $#&
The separations are considered as distances measured perpendicular to theplanned well, so that they lie in the plane of the anti-collision diagram. ‘3D’ or‘minimum distance’ separations are more conservative, but cannot beadequately represented on the travelling cylinder plot and are therefore not partof the Recommended Practice.
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-21
&.+&$,$+3 ..
* # # " $ 080&
1 " # "#$ " " =
A nearby well presents a$ )if a collision with it wouldcarry a significant risk to personnel or the environment. Itpresents a ) if the risk to personnel and theenvironment in the event of a collision would be negligible.
The Major/Minor risk classification is preferable to the more prescriptiveFlowing/Shut-in classification because it forces the engineer to think throughthe implications of collision in differing situations. For example, theconsequences of collision with an oil-producer just above a shut-in SSSVshould certainly be subject to a thorough risk assessment before the well isclassified as Minor risk. Conversely, a collision with the same well in theperforated part of the reservoir section might well justify the Minor riskclassification. Used in this sense, ‘Minor’ is a relative term – a well may beclassified as Minor risk without implying that a collision with it would be of minorimportance.
) " $ # $ " #% "$# &
A well may present a Major risk for only a part of its length. For example, belowthe shut-in point, or more than a certain distance above the reservoir.Calculations involving the mud weight, shut-in pressure and fracture gradientmay be required to establish at which depth the risk classification changes.
4 " # $$
"$$,.(,& *,/
## $ %" $ &
BP AmocoBPA-D-004 Directional Survey Handbook
4-22 Methods September 1999 Issue 1
1# $ " &1 &B " " ## 21/ 1 &
1,1(1 "*$,91B$**C3 ..
1# "08#=
K?σ,GσAGH,GAGSbG&, I,
K?σ,GσAGH,GAGSbG, J,
#
σ, K # ,
&
σA K ' "$ # ,
& 1 " " "" #&
, K ; #&
A K $+ "$#&
Sb K #"&
K & # " ) 4" % $&
Example: Planned well uncertainty at 1 std. dev. = σ1 = 8 mInterfering well uncertainty at 1 std. dev. = σ2 = 5.5 mHole size in planned well = d1 = 17.5" = 0.445 mCasing OD in interfering well = d2 = 13.375" = 0.340 mAllowance for survey bias = Sb = 0 mDrilled depth = DD = 650 m
Separation = 3(8+5.5) + H(0.445+0.340) + 0 + 0.01(650) = 47.4 m
Section A.5explains how relative
surface positionuncertainty is included
in the minimumseparation equation
Section A.5explains how survey
bias is included in theminimum separation
equation
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-23
1,1(1 "*$,91,$**C3 ..
1# # "=
K ( )σσ π
22
1
21 2
1 2lnd d
Rd d Sb
+
+ + +
#=
σ K σ σ12
22+
R K 14
Example: σ1, σ2, d1, d2, Sb as aboveTolerable Collision Risk = R = 1 in 80 = 0.0125
σ = √ [8² + 5.5²] = 9.71 mSeparation = 9.71√ 2 ln [ (0.445+0.340) / [(0.0125)(9.71)(2.51)] ]
+H(0.445+0.340) + 0 = 13.8 m
The risk-based separation equation exhibits some unexpected behaviour.In particular, it is meaningless when
d d
R1 2
21
+<
σ π
This occurs when the relative position uncertainty of the planned and interferingwells is so large that the tolerable collision risk cannot be exceeded even if theplanned well is drilled straight at the interfering well. The minimum separation Inthis case can be set to zero and no-go lines need not be drawn.
1 1 4 14 # " " 3 " " $ # 2 &
For convenience, a risk level may be used which is less than the valuedetermined from the cost-benefit analysis. Thus, for example, directionalsoftware might present a pick-list of rules based on risks of 1/10, 1/20, 1/50,1/100, 1/200 and 1/500. A calculated TCR of 1/57 would indicate that the 1/100risk-based rule should be applied.
For more onthe behaviour of therisk-based separationequation, and itsderivation, see A.5.
Section 4.4gives guidance ondetermining TolerableCollision Risk
BP AmocoBPA-D-004 Directional Survey Handbook
4-24 Methods September 1999 Issue 1
1,1(1 "*$,9 *&C3 ..
9 #% : " " ## : # $ #&
Even when this is done, it is sometimes impractical to apply the standardminimum separations rules immediately below the kick-off point. In this case,good judgement must be used to determine from what depth the standard rulesshould be enforced.
&)
$ # $ $ # & ' 5 % # $ 3 "% #> &
It is occasionally possible to represent drilling tolerance lines adequately on planview or vertical section plots, eliminating the need for an anti-collision diagram.For example, where there is no interference near surface, a single interferingwell is involved, and the interfering well remains either above, below, or to theleft or right of the planned well. Where there is any doubt that the drillingtolerances can be represented accurately, clearly and unequivocally in this way,an anti-collision diagram must be used.
1 $ # " # # . $ ,AV &
1 # # $ # " # # &
Use common sense when it is clear that a particular no-go line cannot beviolated due to the presence of other, shallower drilling tolerances.
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-25
&3
* $# $ $&
$ # $ # #" 3" &
Where the only deviations from the survey program are altered start and enddepths to survey sections, it will usually be sufficient to recalculate theuncertainty in the planned well and to decide if the consequent changes inposition uncertainty are significant. Eliminating surveys from the program,changing instrument types, or radically changing depth intervals will alwaysrequire a full rework of the anti-collision calculations.
# > F + $4 $F+4B&,&
" % " ## $&
,+*,0 1 ,$+$. *,& .,
) "" # # &
' " $ % $ # $ % $ # "" ""&
When a tolerance line has been crossed, or is likely to be crossed if drillingcontinues, the situation must be assessed by the onshore drilling team. Firstly,the anti-collision diagram must be examined to confirm whether
either the tolerance can be relaxed without violating any no-go areas (forexample if the line has been drawn to smoothly join two no-go areas),
or the tolerance line protects only planned well(s) and there is sufficientroom to safely re-plan these at a later date.
In either case, an amendment to the anti-collision diagram with the tolerance linemoved to allow drilling ahead can be prepared. If only a small section of thediagram is affected, it may be faxed to the rig.
BP AmocoBPA-D-004 Directional Survey Handbook
4-26 Methods September 1999 Issue 1
It is always better to provide the rig with a revision to the anti-collision diagramthan with verbal or written instructions. It will usually only be possible to relax atolerance line by a limited amount, over a limited extent of the diagram. Thisinformation is difficult to convey in words.
If the tolerance line protects an existing well, the options to be examined include:
• Plug back and side-track
• Re-survey with a more accurate tool
• Perform a QRA analysis to justify drilling ahead
• Drill ahead with increased survey frequency and alertness (this may beappropriate where a tolerance line is just being ‘grazed’)
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-27
44 &9#
&
11$ 8 "&1 8 "% # """ #& 1"#$$##"" # =
20’40’
60’80’
992’
20’
20’
40’
40’
60’
0’
40’
1976’20’ 40’
planned wellinterfering well
N
S E
W0
180
270 901000’
2000’
4000’
20’40’ 60’
80’3000’
20’2910’
3826’
4779’5000’
4779’
992’2910’
3826’1976’
* + * ,& (* /
' $ # 8 & 1 " $ $ $&" # # 8 &
For moreinformation on theTravelling Cylinderand its uses, see
!" ! #$
%
!
&
#
Figure 4.6
How a nearby offsetwell appears on atravelling cylinder
BP AmocoStandard Practice
BP AmocoBPA-D-004 Directional Survey Handbook
4-28 Methods September 1999 Issue 1
* + * ,& * &$,
' $ % #; # $ & 1 #. " $% 7 . !& " # # # $ ,A! &
1 $ " #$ # $" $$% " & 1 " . " 8 ## %# $ #$ "5 # $$ # " #& 1 $ " "$# $% # #$ " 3 &
* ..,0&/., *&$$*,
$ " # & 1 " " $& % " # & 1 %# $ $&% $#" # $ # ; &) # % % $ $ $ " #&
$ $# $ # 1 # # " $$ & 2" " # &' % % " $#" &
BP AmocoStandard Practice
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-29
2347
2370
Relative Bearing = 96 deg
Radial Distance= 31 m
RelativeDepths
50
40
30
320
300
Interfering Well
,$0$* ,$. *,& .,
1 $" $$ 8 ! $ & "" #% ## # $ "& $ $ # # % % %#$ &
#$$ "" # $ # 3 " & 9 % ## " 7$!& ' $% $ $ $ &1 # &
Figure 4.7
Travelling cylinderco-ordinates
For a step-by-step guide to drawingtolerance lines andcompleting anti-collision diagrams,see'( (
)&
$ * by HughWilliamson, UTG WellIntegrity Team
BP AmocoBPA-D-004 Directional Survey Handbook
4-30 Methods September 1999 Issue 1
*+,0$. *,& .,
1 "#$ "$ # " "$$# &
800
960
900
980
1000
800900
1000
1000
1000
800
Here, there is room to cross the 800 ft linebefore reaching 1000 ft, whilst staying outsidethe minimum tolerable separation. Separate tolerance lines have therefore been drawn.
A separate 800 ft tolerance linehere would be pointless. It could
scarcely be crossed without drillingwithin the minimum tolerableseparation at a greater depth.
Entering this area would violate the minimumtolerable separation at 990 ft, even though
the no-go area has not been plotted
&*
1 14 " # # " ##& ' 5 " " & # $ " " # &
1" "=
1 " 3"C ) &
1 " $ $
V ) &
1" M4$ &
. &
Figure 4.8
Rules andconventions for
drafting tolerancelines
The worksheet,plus 3 completed
examples, is inAppendix C.
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-31
" 14%" #%
# V/C& #% 2 # 3 % # # " $ 14 $ " $ #$% 8 $& " " A 14 "" " # & )
" % " M
F $ # " # "#$ &
*3 "" # 8 " 14%3 ) & ' $% " # =
• 1 " "$ # % # 8 % $$ &
• 1 " "@%#"$% &
• 1 ""$ "3 "5 #
1 # $ $ " $ $ % $ % & ' # $$ &15 5 "#" $ " " 3 &&
BP AmocoBPA-D-004 Directional Survey Handbook
4-32 Methods September 1999 Issue 1
5 ) - $
) & 1 " #$ " "% " "M4 # " & ) #$ " $" " 3&
31*
)04 3 $ " $ ""#%# "&' @ 0$ '& " ' % .# U&1 2 B%EB%ELS B%B,B%L?,B%-BC%EA-&*5$ " $# > &
"*,&".
$ " # $ $ # #& 1" 0) $ #& # 0) "$ ""& " #&
eletromagneticfield lines
well to beavoided
wire insidewell carrying
current I
conductorelectricallygrounded
wr
B
MWDsensors
well beingdrilled
For more on thepractical limitations of
QRA applied toanti-collision see
+, ,
!( & -&.)
/&
0 -&
For moreinformation see
++
&
# 1&$
$
$ -$$
!"2
3
&.
Figure 4.9
Principle of singlewire magnetic ranging
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-33
'" "$ # % $$$&1" # # &'" % ?," " "" & 1 "#% "$ # "#$ &
"5 "$ # " #0)% # $ # & ""$ $ $ " # * ! $ " "
%$8 "%B, #& 1 " % r % " 0) "$
#% ! 6#% ( )Br
r w= ×µ
π0
22
I # w
"$#& 1 r $ 8 " 3 =
( )rB
w B= ×µπ
022
I &
"".&$,," *+$*1,&
)04 # # $ # # &' "" # "$# # # " # 8 & # "$# $$" 3 " " $ &
BP AmocoBPA-D-004 Directional Survey Handbook
4-34 Methods September 1999 Issue 1
1$" % # 5# " % " 0) & ) %
,A % "± " , " ±,B" A " 5 % # 5 $ " AB" &
' $ 21/ $#" &
4:
1 % $$8 "#" ""# &' "% " 3 # # " $ & " %# ,T $$ 8 &)"
'$ " $&
' $ $ ! &
* " & # $ " 5 $ "$ & # 3 $ & 1 # $ $ $$ & 4 " $3 &
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-35
5
1 " $$ $ # # "" " 6 &'"$&, # $$ $ #& / %, " # $ #"$&,&
geological target
surveyedwell path
2 s.d. error ellipse
(a) (b)
apparent pointof penetration
*$ " , # # "$ $$ $ & ) $ " $$ $ " LAT& $ $$ $ $ $ &,,&
Figure 4.10
Calculation of thedriller’s target
BP AmocoBPA-D-004 Directional Survey Handbook
4-36 Methods September 1999 Issue 1
> 95%90% - 95%
< 90%
welldirection
(c) (d) geological target
driller’s target at95% confidence
inclusion probability
9% # " " $$ $ # # % % LBT% 7! $ LBT"!&1# &,,% $ &
'&'.
1$$# 2 $$ $ ! $ % " $ & ' % " $$ $ % ! $ " $ " $ LLT%# $ $"" & 9 $$ $ % 5 #% ; $ #% & #% "$ ;" ! $ $ "#$=
5 $ $$ $ # $$ &
* $ &
$ # " $&
Figure 4.11
Calculation of thedriller’s target (contd.)
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-37
$"" $ # $$ &
""LBTLT " 3& ! $ " LT" 5 &'5 % " # 3 &
'''##
1 ;" ! $ 7 !#! " $$ $ & 0 $ " ; " # # %#" $& 5 % ; $ # ; #&
highsideuncertainty
Low angle well
(1) uncertainty is magnifiedby foreshortening
highsideuncertainty
High angle well
(2) target is truncated at near andfar edge by magnified uncertainty geological target
driller’s target
# %" $$ $ " $ $"$ "" " $ $ & 1 5 % "" =
amount of target truncated at front & back
= highside uncertainty / cos (incl)
9 3 # % #$! $ LET"&
Figure 4.12
Effect of holeangle on size ofdriller’s target(side-on view)
BP AmocoBPA-D-004 Directional Survey Handbook
4-38 Methods September 1999 Issue 1
&'5
0 $ # " #& $ " # " " $ " $ &
% ! $ # " $ & 1 $ 3 &
'D3
" " $"" # $ $$% $ " ; # " ; & 1 " $$ $ "" & 1 " % 5 % 1 " #& ! $ " % 8%"$! $ #&
entry plane
exit (or TD)plane
geological target volumedriller’s target volume
directionof well
'" $ $% "" ! $ 7 !&% # #& 1 $$ $ $& ' 8 $ $&
The BP Amocoalgorithm and thegraphical method
are described inSection A.4
Figure 4.13
Driller’s target volumefor a horizontal well
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-39
geological target volume“pinched-out” driller’s target
directionof well
4; &
1 5 $ "# " $# . %* %1@%" % %; &13 " " 5 $" % # $ % $ $ 5% # $ ' & 1 " % # $ # &
' " # & 7 " !% 7$$!7 $ ! " % % $& 1 % 8 # $ " # $ % "# # &
Figure 4.14
Pinched-out driller’starget – a case forgeosteering
The minimumcurvature equationsare given inSection A.1
BP AmocoStandard Practice
BP AmocoBPA-D-004 Directional Survey Handbook
4-40 Methods September 1999 Issue 1
*&
1 " $$ % ; " # % & ' %## 8 " & 2" % " 3 % & %#$ $" % &,&
4< *'
' "$ '4 $ 3 $ # " 8 0) & ' $ & $ % 5 . &
"#'*
' "$# $ "0)$ " % $ ; # 3 # 0)& 1 #8 " 0) ; :$ 5 $ " : $ $ ! $& 0) " # # # 0)> &
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-41
## '*
' "$ #
• 1 #$ A°
• ; A" # $ # '4 :#
• 1 $ ; 5 705$ !#
# -
' %0) " $ # $ # $ &
' "$ $ 0) & ' %# &
)#&
' "$ 8 $ & ' ! $ 3 $ : " & $ " # $ # # # " # 0) &
It is vital that all IHR corrections are checked forreasonableness as well as numerical accuracy, and thatunusually large or highly correlated corrections areinvestigated by a survey specialist.
Survey datacomparison isdescribed inSection 4.10
BP AmocoBPA-D-004 Directional Survey Handbook
4-42 Methods September 1999 Issue 1
*"
1 # $ # & ) " $ # $ % " # "# &
gyro multishotsurvey
in-hole referenceinterval
IHR MWD surveys
MWD surveys
BHA #1
BHA #3
BHA #2 BHA #1
BHA #3
BHA #2
,& # B " ,B , " ? " $ # $ & 1 $ # #5 " $ " #&) % # $A" 3 & 10) " $ # $ # $&
Figure 4.15
In-hole referencing –section drilled with
multiple BHAs
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-43
A& $$ 1" & 1 3 # $ "$ $ $ "$ $ & AB" , &1 &
?& + #
"# &1 =
" $ # $ "" " $ "&AB" CB&
A" -$ &
# ; " &B° # &
1 > '4 % 705 $ !#&
& " % # $ % 0) # '4 & 1# %# "$ # "
L°% $ ; &
"" '4 &1 &1 " $% "0) 5 "$ &
B& ; # 3 0)> # $ &
BP AmocoBPA-D-004 Directional Survey Handbook
4-44 Methods September 1999 Issue 1
&.&(.$,$+*&$** &$,9
1(.". -
) $ % '4 " $ $0) ; # "; &1"#$ 5 =
MeasuredDepth
GyroAzimuth
MWDAzimuth
BHA # InterpolatedGyro
Azimuth
IHRCorrection
CorrectedMWD
Azimuth1250 271.62°1275 271.81°1300 271.77°1325 272.04°1350 272.16°
1315* 272.7° 1 271.93° -0.77° 271.93°1413 273.6° 1 -0.77° 272.83°1508 274.1° 1 -0.77° 273.33°1604 274.3° 1 -0.77° 273.53°1255* 272.1° 2 271.66° -0.44° 271.66°1699 274.2° 2 -0.44° 273.76°1793 274.7° 2 -0.44° 274.26°1300* 272.9° 3 271.77° -1.13° 271.77°1886 276.1° 3 -1.13° 274.97°1980 276.2° 3 -1.13° 275.07°2073 276.5° 3 -1.13° 275.37°
* In-hole reference station
* *$" & &$** &$,$+13(* /
' ; # '4 &'" 0) # '4 % ; " $"$ " &
Table 4.2
Calculation of in-holereference corrections– section drilled with
multiple BHAs
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-45
1$+ "*$& (* +$*,0. - &$,
) $ ## $%5 '4 =
gyro multishotsurvey
MWD surveys usedfor calculating IHR
correction
IHR correctedMWD surveys
MWD surveysrejected due to
external magneticinterference
,& ' " $ A" % '4 " 0) & 1 "#$0) 5" =
• 0) # # " 5 $ " 5 $
• 0) # "
5 $; J&B° #
• 0) # '4 #3"" $
Figure 4.16
In-hole referencing –section drilled withsingle BHA
BP AmocoBPA-D-004 Directional Survey Handbook
4-46 Methods September 1999 Issue 1
A& 1" " $ $ 0) % $ &
?& 1 # &
& " % '4 "#$ &
1"#$ ##$'4 =
MeasuredDepth
GyroAzimuth
MWDAzimuth
Interp.Gyro
Azimuth
AzimuthDiff.
IHRCorrection
CorrectedMWD
Azimuth6200* 83.23°6300 83.06°6400 82.69°6500 82.24°6600 82.38°6700 81.60°6800 81.45°
6276 82.1° 83.10° 1.00°6370 81.6° 82.80° 1.20°6467 81.3° 82.39° 1.09°6562 82.2° 82.33° 0.13° reject †6655 81.1° 81.95° 0.85° reject ‡6749 80.7° 81.53° 0.83°
mean +1.03°6842 79.9° +1.03° 80.93°6936 79.1° +1.03° 80.13°7030 77.9° +1.03° 78.93°7125 78.0° +1.03° 79.03°
* For illustration only – reference survey interval should be 25 ft or10 m.† Rejected – statistical outlier.‡ Rejected – azimuth change between reference survey stations>0.5° (Azimuth change between 6600 ft and 6700 ft = 81.60° –82.38° = -0.78°).
Table 4.3
Calculation of in-holereference corrections
– section drilled with asingle BHA
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-47
121(1&,0 ,$. * &$,
'"$ ; "" $0) $ & 1 " $ % " 5 $ " $ $&15 $ & 1 "#$ " $ $ $"0) " &L" =
Max. change in sin(Inclination)sin(magnetic Azimuth) ≤ ±0.25
Example A proposed IHR section starts at 65° inclination, 150° magneticazimuth, and finishes at 75° inclination, 130° magnetic azimuth.
Is this change in hole direction acceptable ?
Answer sin(65°)sin(150°) - sin(75°)sin(130°) = 0.45 - 0.74 = 0.29
The change in hole direction is too great, and IHR cannot be applied over thewhole section.
,$. * + * ,&,0$+ . &*$,&1(.$
* " # 0) # $ & ; " # "%" 5 $5 $ " &
BP AmocoBPA-D-004 Directional Survey Handbook
4-48 Methods September 1999 Issue 1
4= +*'
$ 3 " "$ & $ $ % 3 " $ $ " $ & . "$" $$ " /$ //$ 0 //0& #% $ $ " " & 1 " " "" # $$ "?&A&
'% $ # $ " $ " # $ & 1 & 1 3 " " "$ ''94 5 & ''94 "" " $$ " # $ " $ "&'"" 7 !$ % $ $ " $ 3 &
Observatory
Measured Fieldat Observatory
Calculated Fieldat Wellsite
Mean Offset DerivedFrom Wellsite Survey
Wellsite
For a completediscussion of
interpolation in-fieldreferencing, see +, -
)/
&
1
!" $"
00
4(
5*$ )
6 - $
!"2 and ,
00
0 )
6 - $
-*
7&"
8&
Figure 4.17
The IIFR principle
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-49
1+1
+% 7 !" $ " $ 3:3 # % $ $ 3&+""% %$ "& 1 " $ 3"$ 5 &
1$ " "$ "$ # " $ & 1 " $ " " $ & " " %" $$$$ "& 1$$ "" & 1 " " " $ " "&1 # $=
1 " & 1 " " " $ &
1 ; "&$ """# #" % 5 $; "&
1 # $ B B &
BP AmocoBPA-D-004 Directional Survey Handbook
4-50 Methods September 1999 Issue 1
1$ # 5 " $$ " " " $" #$ &)5 %5 $ " " $" &
+*'$#
'94 & ' 3 " $3 %$ " 5 #$ ""& 1 $$5 &
.$,$+10, &+ ..(
$ " " " " % 3 & 1 $''94 0)# $ $# $ & 1 %"# $"" =
• 4 $ " # # " $ $5
• '" $ #% " 0) %
• ''94 0) ; # "0); &C
"".&$,$++*
% " ''94 3 &1$ $ " &1 # " ''94 #3&
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-51
!
Real time(rig site)
Regularturn-around
(office)
D#$" " # #& 9 % " $ $&1 "% $ " ##% "5 #" 8 "& % " " $ $ # $ 3 $&
0)3 $ " $ % &* $ # $ & *5 $ $ % $ % G>, "" % 0)>$$ $& 9 3 55 $ " " $ 5 " 3&
Figure 4.18
Typical processsequence in an IIFRoperation
BP AmocoBPA-D-004 Directional Survey Handbook
4-52 Methods September 1999 Issue 1
$"$,+$*"*$& ,0
1 " $ " $ # # ''94&1 $ 3 5 &1 "" "$ % 5 " $ $ 5 & 1 % # # = " $ $ % " " " # & 1 "; "#&
OPTION 1 Correction for crustal field declination 1$ " $ " " $ ; & % #3$ " & $ "& 1 $ & "" # " " %$ 3 " &
OPTION 2 Correction for crustal field declination anddrillstring interference
"5$ "$ "$ " $ " $ &1 # " $ $ " # " &+ # "#$"; # 5& * " $ " $ $ + , "#&
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-53
OPTION 3 Correction for tool sensor errors, field variationand interference using near real-time data
1 "" " B&A # " # 5 "$ " " $ "& / $% " % """ ""# $ &
+* 8( ,&/$+ . */
1 "3" $ 3 #=
• D $ $ " " #
• $ " " # "" $
• 0$
$ " $ % " 3 % " # " " & ' " $ $ % ##$ " # % #3 "# &'" " $''94 " " # % " $% $ $ &
0 $$ $ " &1# # $ &
BP AmocoBPA-D-004 Directional Survey Handbook
4-54 Methods September 1999 Issue 1
*& 1,0 1 ,,&$11(,&$,
3 " ''94 "$ & 1 % $ % 0) " $ & 4 $ &1" "53 5 &
PermanentMagnetic
ObservatoryLogging
UnitDirectional
Engineer’s Office
GeomagneticData Centre
IIFR DataProcessing Office
ObservatoryData (real-time)
Observatory Data (bulk)
IIFR ProcessedMWD surveys
RAW MWDsensor data
$3, *"," ,*0
1 " 7 $ ! # % 8 1$ 2D . * 4 /$ )+LC,,?& ) $ $ " % / # $ " " &
1 "$ " $ " % $"$ " $ & ' ""$" # "21/&
Figure 4.19
Typical data flow in anIIFR operation
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-55
4> 1'
0$ " " $ ""$ &' # =
• $ $5" % $ & " $ "5
• 0 $ $ $5" & ' "" " #7!
!'
1 " 5 " $ ' "% " &
-& $*/
0$ $ $ % # $
& 1" %B%
" " $ %P% ! %z:
BP
zm =4 2π
Bm1K,1%z %
")µ)& $ "
µ)% ,&& " " & ' 5&
BP AmocoBPA-D-004 Directional Survey Handbook
4-56 Methods September 1999 Issue 1
1 5 "$ "% % " " "" " &9$ &A # # # " # "$ &' " # & 0$ % $ # &
z1 z2
P1 P2
Drill Collar Mud Motor BP
z
P
zax = +
1
41
12
2
22π
z1
z2
P1 P4
Drill Collar Mud Motor BP
z
P
z
P
z
P
zax = + + +
1
41
12
2
22
3
32
4
42π
Stab.
z3 z4
P3P2
magneticsensors
magneticsensors
1"&$,- 0,
1; %∆az%5$ " 5" " % % $ " " "$"&) "$"# ; " * ! "% "#$ 5 " 5 =
( ) ( )∆azax
H
B
BInc Azi=
180
π. .sin .sin
# BH ; $ " $
?&A " 5 % Inc Azi $ ; &
'$%$
"5 " $ &B°& 1# " $ $ ,&&
Figure 4.20
Estimating magneticaxial interference
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-57
2., *+ * ,& &$** &$,
$ # " 5 " " & 1 # "$&A,=
magnetic north(direction relative todrillstring unknown)
B
apparentmagnetic
northaxial
interferencevector
(magnitudeunknown)
Bax
B + Bax
Problem
(3) and we know the Earth’s field vector is this long:
(2) and we know the interference vector acts in this direction
(4) so we can work out that magnetic north is in this direction
B + Bax
(1) we can measure this vector
Solution
1 "$ $$ "#$ " =
• 1 #$ " * !$ "& ) &""$ "% # $
• 1 " 5 "5 "&L
• . " $ " * ! " " "&2" % # "" "5 " # : # # ; $ #
Figure 4.21
The principle ofsimple axialinterferencecorrections
BP AmocoBPA-D-004 Directional Survey Handbook
4-58 Methods September 1999 Issue 1
• " % "#$ #$ =
• $ # & 1 " $ & 6 $ "55 $ "
Drilling Area MaximumAcceptableCorrection
Gulf Coast, Middle East, Far East, Africa, South America, FSU 6° North Sea, Northern Europe, Canada, Norway 8° Alaska 10°
• # ,? " "$ $ & ) %5 " &
• 5$ " # " 5&LB& 1 "#$ " " =
Azimuth of Well Forbidden Inclination Range
Magnetic E or W ± 19° or more no restriction
Magnetic E or W ± 18° 87° – 93° Magnetic E or W ± 15° 80° – 100° Magnetic E or W ± 10° 75° – 105°
Magnetic E or W ± 5° or less 72° – 108°
'$ % " $" $&
Table 4.4
Maximum acceptableaxial magnetic
interferencecorrections, by region
Table 4.5
Forbidden holedirections for axial
magnetic interferencecorrections
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-59
1(.$,,./
8 $ # 0) # $ 5 " & 1 7 ! 3 0) & # # " $& & 1 $ " """"$# " " $&
0 " $% $ " " & 1 " $ 0)% $" " $& 1 " &
4? &)#
" $ #" $ " 3 $& 1 :1 % % #4 ' "4'&
*A)'&)#1
M 3%$ $" "" # &7$" ! " 7 !&1=
• 1 $ # $" "$ #
The developmentand validation ofINTEQ’s method isdescribed in ,
00
0) #
$
$ "*
BP AmocoBPA-D-004 Directional Survey Handbook
4-60 Methods September 1999 Issue 1
) $" "" "% 5 % # " &1=
• 1 $ $ " %## "
. " "" 3 % " &
"
1 $ #$ " # & 1 " $ " 5=
Incl
inat
ion
Azi
mut
h
MD5
30
25
20
15
10
40
35
315
340
335
330
325
320
350
345
500 2500200015001000
MWD
Gyro
1 #" $ $ " & "" % " & 1 # $ " $ " $&
Figure 4.22
A Survey T-Plot
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-61
1 1
&,°>A°>&9 %1 EH[5,,[ " :5 $#$" " 3 &
1 ## $"" # $ # 5 $ "&13 "#$ &
#1
$" " " &* %" %" # % # # & ) 3 " !$ &
9 % # # & 1 ; % " $1@& 9 $ $ ; #% # $ &
9 $"$ >$ $=
Overlap at 1 s.d. Good agreement. No further investigationnecessary.
Overlap at 1.5 s.d. but not at 1 s.d:
Average agreement. No furtherinvestigation necessary.
Overlap at 2 s.d. but not at 1.5 s.d
Poor agreement. Recheck both surveyscarefully.
No overlap at 2 s.d. Disagreement. One or other surveyalmost certainly contains a gross error.Investigate to resolve the discrepancy.
The equations forcalculating theseellipses are inSection A.2
Table 4.6
Rules-of-thumb whenusing the error ellipsemethod
BP AmocoBPA-D-004 Directional Survey Handbook
4-62 Methods September 1999 Issue 1
2" % " " $$ " " % >" "& 1 # 73 !& #% " " # =
• 1 # & $""
• 1 #
• 1 #
) % " # & 1 # # % "$ # % # $ &1 % $ $&. " ;" & " # " # &
Ratio (R) ofellipse sizes
R = 1
R = 3
R = 2
1 s.d. ellipses 1.5 s.d. ellipses 2 s.d. ellipses
2 %
3 %
4 %
37 %
41 %
45 %
11 %
13 %
16 %
Probability thatellipses willnot overlap
Table 4.7
Quantitativeinterpretation of theerror ellipse method
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-63
*)"')
4' " 3 " & ' ; "" # # # "" 5 " & 13" "#=
• $
• =
∗ ' "
∗ - $ " "
∗ , && " " $
∗ , && "" # " 3 "
∗ "" , &&"" $
• 9 " "" #
• 4 "; ""
BP AmocoBPA-D-004 Directional Survey Handbook
4-64 Methods September 1999 Issue 1
MD Comparisonsurvey
azimuth
Interpolatedreference survey
azimuth
Observedazimuth
difference
1 std.dev.azimuth
difference
Normalised azimuthdifference
(ft) survey 1 s.d. survey 1 s.d. (std dev.)A B C D E = A - C F = √ B²+C² G = E / F
1349 135.7° 0.78° 136.61° 0.35° -0.91° 0.85° -1.061444 136.4° 0.78° 137.54° 0.35° -1.14° 0.85° -1.331538 136.9° 0.79° 137.81° 0.36° -0.91° 0.87° -1.051632 137.2° 0.81° 138.45° 0.37° -1.25° 0.89° -1.401727 136.9° 0.82° 138.59° 0.37° -1.69° 0.90° -1.881822 137.7° 0.82° 139.02° 0.37° -1.32° 0.90° -1.471916 138.9° 0.83° 139.66° 0.38° -0.76° 0.91° -0.832011 138.1° 0.84° 140.45° 0.38° -2.35° 0.92° -2.552106 139.5° 0.84° 140.73° 0.38° -1.23° 0.92° -1.332200 141.6° 0.84° 141.75° 0.39° -0.15° 0.93° -0.162294 141.6° 0.85° 142.18° 0.40° -0.58° 0.94° -0.622388 142.7° 0.86° 142.89° 0.40° -0.19° 0.95° -0.20
mean 1.56 s.d.std. dev. 0.65 s.d.
$ " & $ " $ % # $& $ " $ "&
Table 4.8
Example of a RelativeInstrument
Performance analysisfor azimuthdifferences
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Methods 4-65/66
1 "#$ % 5 % # =
Normalised Difference(Incl. or Azim) Interpretation
Mean Std. Dev.
< ± 0.5 and < 0.5 Good agreement
± 0.5 to ± 0.75 or 0.5 to 1.0 Average agreement
± 0.75 to ± 1.25 or 1.0 to 1.5 Poor agreement.
Re-check both surveys carefully
> 1.25 or > 1.5 Disagreement.
One or other survey almost certainlycontains a gross error. Investigate toresolve the discrepancy.
Table 4.9
Rules-of-thumb foruse with RelativeInstrumentPerformanceanalyses
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-i
Section 5
Contents
Page
5-1
5-4
5-11
! "#$%& 5-13
'#(% 5-24
) *+%#& 5-26
, - 5-28
. /%%0% 5-29
1 - 5-31
2 3+4 5-35
Figure
5.1 Sensor arrangement in G yrodata’s Wellbore Surve yor(large diameter tool) 5-15
5.2 Keeper tool configured for a 9-5/8" or 7" casing survey 5-19
5.3 The RIGS surve y probe 5-23
BP AmocoBPA-D-004 Directional Survey Handbook
5-ii Survey Tools September 1999 Issue 1
Section 5
Contents (cont’d)
Table Page
5.1 Position uncertaint y for inclination onl y surve ys 5-2
5.2 Qualit y measures for electronic magneticmultishot surve ys (generic) 5-13
5.3 Qualit y measures common to all G yrodata surve ys 5-17
5.4 Qualit y measures for G yrodata g yrocompassing surve ys 5-18
5.5 Qualit y measures for G yrodata continuous surve ys 5-18
5.6 Qualit y measures for Keeper multishot surve ys 5-21
5.7 Qualit y measures for RIGS surve ys 5-24
5.8 JORPs documents currentl y in use 5-37
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-1
The surface and subsurfaceinstrumentation used in wellboresurveying.
Recommended Practices for tool selection and operation arein italics.
!"
"
BP AmocoBPA-D-004 Directional Survey Handbook
5-2 Survey Tools September 1999 Issue 1
5--
Their use should be restricted to near-surface sections ofisolated exploration wells or well-spaced development wells.
#$
"
AverageMeasuredInclination
Position Uncertainty at 1.s.d.(ft/1000ft or m/1000m)
0° 13
0.5° 22
1° 31
1.5° 39
2° 48
2.5° 57
3° 65
" %& '( ) ) *
Inclination only sections near surface should normally beresurveyed later in the drilling operation.
" + ,-.
Table 5.1
Position uncertaintyfor inclination only
surveys
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-3
-
" " TOTCO "
6 "'7" +
TOTCO " "
" /TOTCO) 0# # "
6 "'7" +
"Teledrift 1 % /) $ #
Anderdrift
# 2
" -3° "
4°$-3° 53°$64°$
BP AmocoBPA-D-004 Directional Survey Handbook
5-4 Survey Tools September 1999 Issue 1
5--
" 0#'# % " " 0# %7
• 8 9 %+92%. (
• ( ( ( % 0# " $
-
% $ + . $ + ,:. "
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-5
" ' $ ;$6<-= ! $ +. '$ !,$><,=
55+5"57
% " " $ 7 ? ? < # %
" $ # % + . $ 2
BP AmocoBPA-D-004 Directional Survey Handbook
5-6 Survey Tools September 1999 Issue 1
% $ 0 0# "
+ '"57 "+
# % 2 2 ) ) ( 2 )
" ( " (
-
1 " ! " $$
785' 50+ "
% 0# + . " " % + 36. 0# " 0# %
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-7
The determination of this offset is a safety-critical task, andmust be checked independently before the BHA is runin hole.
% 0# % " ! 0#
& %
+ >°3°.0#
+@4°@6;4°@-54° @:4°. "
9+5:; '40 55
% ( ! "
Six-sensor ‘raw’ data should normally be transmitted tosurface, with inclination, azimuth and toolface (andassociated QA measures) being calculated from it.
<5%;%
All MWD surveys must pass a number of internal andexternal validation checks. Details are below and in JORPs.
" +"57<057=50+5"'
" /$)% 7
• A$
• $
BP AmocoBPA-D-004 Directional Survey Handbook
5-8 Survey Tools September 1999 Issue 1
• !
" $ % ( B#+,:.
> +"5755;575"
2( B# "
Each MWD tool must pass a comparison with external data.
" 7
CHECK SHOTS
2 0# +,%. ( ! 0# $ # 7
( 7 43°
( !7 >4°
C #
Section A.3contains details of
how to calculate these quantities
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-9
%<0# ( !7
( 7 4-3°
( !7 63°
% #
Whenever possible, MWD tools should be changed outduring bit trips.
" %
ELECTRONIC MULTISHOT
( +21.% " 0# $ % 0# 21
MULTI-STATION DATA ANALYSIS
% $ +,5. $ + ,:. ( 2($ + . %
BP AmocoBPA-D-004 Directional Survey Handbook
5-10 Survey Tools September 1999 Issue 1
4 "5"8+ > +"57;575"
2( % 7
• "%3° $
• "% $
5&" '0+(5"' "+"&
2 % $ 1
5
# % # $ + ,5. $ + ,;. +,:.
# !
" 0# 1 ( "'# +.
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-11
2 +21. " $ +33.
5--
21 " % 21 %% 21 ) 21
21 6444 1 +211. " %
-
21 64=-4=&" " $
two probes should be run in tandem for all EMS surveys.
21 % 1 + #1 ".
BP AmocoBPA-D-004 Directional Survey Handbook
5-12 Survey Tools September 1999 Issue 1
-
"
" + /TOTCO
).0##
% ) )
""#5&" '45'"&
" $
Non-magnetic spacing requirements for electronicmultishots are the same as for MWD, with the additionalrequirement that neither sensor be within 1.5 m (5 ft) of atool joint.
+5"6
D 21 " ;$64 " C E&C' +364.
MWDnon-magnetic spacing
requirements arein Section 4.9
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-13
<5
B# % 21" 7
QA measure Tolerance Failureindicates
Possible cause(s) of failure
Divergence betweenprobes – Lateral
< 5/1000 Systematicazimuth error
magnetic interference
Divergence betweenprobes – TVD
< 2/1000 Systematicinclination error
tool misalignment or BHA sag
Gravity FieldStrength (G-total)
< ±0.007g*
(all surveys)
Inclination andazimuth error
Faulty accelerometer or toolmovement
Magnetic FieldStrength (B-total)
< ±700 nT*
(all surveys)
azimuth error magnetic interference, largecrustal anomaly
Magnetic Dip Angle < ±0.7°* (all surveys)
azimuth error magnetic interference, largecrustal anomaly
* difference from modelled value
! "#$%&
* / ) " * 2 # ( % $ 2 " ("*
! 2 ) " * " 7
0! 2 C @Ω@634,6+Latitude.<
" $ 2 )
Table 5.2
Quality measures forelectronic magneticmultishot surveys(generic)
BP AmocoBPA-D-004 Directional Survey Handbook
5-14 Survey Tools September 1999 Issue 1
&%"#$&
A )Wellbore Surveyor +GWS. $ 54F 53F " ( " Battery/Memory +RGS-BT. "G+RGS-CT. $$ 63°
5447'5"
" Wellbore Surveyor 7
• 1
• %
"
Continuous7
• G <
• $
"Battery/Memory( 7
• 1
• + .
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-15
7 '+4"
" " H +-4 . "& --3=>H= # & 653=
accelerometer(non-rotating)
Universaljoints
exciter/pick-off coils
torquercoils
gyroscope(rotating)
magnet assemblyfor torquer coilsto force against
motor/statorand bearingassembly
" -$ ( -$ ( "
" (
Wellbore Surveyor Battery/Memory$+ ! .
Continuous + 63° . !
Figure 5.1
Sensor arrangementin Gyrodata’sWellbore Surveyor(large diameter tool)
BP AmocoBPA-D-004 Directional Survey Handbook
5-16 Survey Tools September 1999 Issue 1
4 +5"57 <0 "' ?'""00076
0+; =
% + ( .$ $
9 64°$63° "
#64°$63° ! "">4" C$
64°$63°
9 / ) "
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-17
4 +5"57 <0 "' ?+40+; =
% Battery/Memory ( +( $ .
" + . " < # B# (
<057=50+5"'
" 7
QA measure Tolerance Failure mayindicate
Possible cause(s) offailure
Field roll tests –mass unbalance(if possible)
< 0.4°/hr poor initial azimuthreference
gyro calibration shift
Field roll tests –accel. scale factor(if possible)
< 0.00015 systematicinclination error
accelerometer calibrationshift
In/Outruncomparison –inclination
Csg: mn,sd<0.3° D/P: mn,sd<0.3°
inclination error depth error or runninggear.
In/Outruncomparison –azimuth
Csg: m, sd<0.5° D/P: m,sd<0.75°
azimuth error depth error or poor gyroperformance
Final zero depth < 2.0/1000 systematic error,primarily inclination
wireline slippage orstretch – correct to CCL
Wireline stretch atTD
< 1.5/1000 systematic error,primarily inclination
tool lag on inrun –correct to CCL
Table 5.3
Quality measurescommon to allGyrodata surveys
BP AmocoBPA-D-004 Directional Survey Handbook
5-18 Survey Tools September 1999 Issue 1
QA measure Tolerance Failure mayindicate
Possible cause(s) offailure
Single station test –Earth rate
< f1(Inc,Azi)°/hr* poor initial azimuthreference
noisy data – reinitialisedeeper
Single station test –gyro drift & noise
mean<400 bits s.d.<400 bits
poor initial azimuthreference
noisy data – reinitialisedeeper
Single station test –accel. drift & noise
mean<50 bits s.d.<50 bits
azimuth error poor gyro performance ortool movement
If1(Inc,Azi) = 1/cosInc√[(0.1°sinInc.sinAzi)²+(0.08°)²]
QA measure Tolerance Failure mayindicate
Possible cause(s) offailure
Initialisation - inclination
s.d. Inc < 0.1° Tool movement orcalibration shiftduring toolmake-up
knock during toolmake-up
Initialisation - azimuth
s.d. Azi < 0.2° tool movement orcalibration shiftduring toolmake-up
knock during toolmake-up
Initialisation - Earth rate
< f2(Inc,Azi)°/hr* Tool movement orcalibration shiftduring toolmake-up
knock during toolmake-up
Drift tune – X gyro <0.2°, allparams
invalid survey poor gyro performance
Drift tune – Y gyro <0.2°, allparams
invalid survey poor gyro performance
If2(Inc,Azi) = 1/cosInc√[(0.1°sinInc.sinAzi)²+(0.08°)²/6]
Table 5.4
Quality measuresfor Gyrodata
gyrocompassingsurveys
Table 5.5
Quality measuresfor Gyrodata
continuous surveys
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-19
*
" Keeper Finder 1 ) $
5447'5"
"J 7
• G <
• $
• 1 % $ $ + .
• 1$ + ).
" / )
7 '+4"
"J " 3+6H.$ 3$64 +6H$>>. $ "& >= $ 653=<6;3=<-6-3=
Zener Sub
Keeper Gyro
Cablehead
Decentraliser
Casing Collar Locator
Gamma Sensor
Temperature Sensor
Decentraliser
Pressure Barrel/Heatshield
6.35 m/ 21 ft
Figure 5.2
Keeper toolconfigured fora 9-5/8 or 7 casing survey
BP AmocoBPA-D-004 Directional Survey Handbook
5-20 Survey Tools September 1999 Issue 1
" +K L. +K M. " K $ ! -4° "L ! -4°
4 +5"57 <0 "' ?0760+; =
% + ( . +$. 4° >° $
# - / ) " / )-4° ""/ ) 6363°
# " + .
" ( /)
% $
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-21
4 +5"57 <0 "' ?"&7 60+; =
9
" ! *$
+N>°."
# $ ) # >,
<057=50+5"'
" 7
QA measure Tolerance Failure mayindicate
Possible cause(s) offailure
Field calibration –mass unbalance
DI < 0.6°/hr
DS < 1.0°/hr
poor initial azimuthreference
gyro calibration shift
Field calibration –accel. scale factor
< 0.0033 v/g systematicinclination error
accelerometer calibrationshift
Initialisation – gyrobias uncertainty
< 0.017°/hr poor initial azimuthreference
noisy data – reinitialisedeeper
Initialisation – Earthrate horizontal
< 0.07°/hr poor initial azimuthreference
noisy data – reinitialisedeeper
Low angle Mode –average G bias
< 0.8°/hr azimuth error poor gyro performance ortool movement
High angle Mode –average G bias
< 0.15°/hr azimuth error poor gyro performance ortool movement
Final zero depth < 1/1000 systematic error,primarily inclination
wireline slippage or stretch– correct to CCL
Wireline stretch atTD
< 1.5/1000 systematic error,primarily inclination
tool lag on inrun – correctto CCL
In/Outruncomparison –inclination
Csg: sd<0.2°
D/P: sd<0.4°
inclination error depth error or runninggear.
In/Outruncomparison –azimuth
Csg: sd<0.5° D/P:sd<0.75°
azimuth error depth error or poor gyroperformance
Table 5.6
Quality measures forKeeper multishotsurveys
BP AmocoBPA-D-004 Directional Survey Handbook
5-22 Survey Tools September 1999 Issue 1
($6" <
C A1 C$O A
5447'5"
!C A1 +H6= . " $ $ "
" 644°G # ( +. 634°G ( 6-44FGH + 5= .
( " / $) 54° ;4° # !
# GGO $ /C A1P) " C A1 C A1 "
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-23
7 '+4"
" C A1 & 3-3= 6;4+,44. D 3;53= --3+344. 1 >:3 +;54.
" D + D. " D " $ ! * 2 "8 $ D 9 *1 C A1 $ ) $
4 +5"57 <0 "'
C A12 " " H 6- + .
PressureBarrel
Electronics
Gyro/
Accelerometers
BreechLock
CableHead
RollerCentraliser
RollerCentraliser
Figure 5.3
The RIGS surveyprobe
BP AmocoBPA-D-004 Directional Survey Handbook
5-24 Survey Tools September 1999 Issue 1
( H,44< +-6444<. " " BG "
<057=50+5"'
* G )
" 7
QA measure Tolerance Failure indicates Possible cause(s) offailure
Alignmentsummary
< 0.1° Noisy Alignment Excessive ‘electrical’noise
Tool movement.
Drift checks < 0.08 ft/min Tool movement, orinvalid survey.
Poor Alignment (1st check)
Lost heading.
Sensor failure.
Tool movement.
In/Outruncomparison
within tool-definedellipses ofuncertainty
Out of specperformance at somestage in completeinrun/outrun survey. QCflow chart will indicatewhether sufficient QCparameters exist toqualify survey as withinspecification.
Depth error.
Sensor failure.
Lost heading.
'#(%
G $ $ / ) % "
Table 5.7
Quality measures forRIGS surveys
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-25
5--
G $ 7
• $
• " (
• "
G $ $1 + ,-. $ 2
Camera-based magnetic multishots are not a recommendedtool type.
# ( $ $
-
" 7
• # #
It is strongly recommended that only units ranges between0-10° and 0-24° be used.
BP AmocoBPA-D-004 Directional Survey Handbook
5-26 Survey Tools September 1999 Issue 1
1 O
• # ! "
• # " $ $
-
0# " $ 1 %+,:. "
<5
1 OB#
) *+%#&
1 $ 1CA D $ $ "
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-27
( " !
5--
$ $" $ 0# ( " $ ($
SRGs must not be used:
• For multishot surveys
• Deeper than 450m/1500ft below rotary table
• In hole inclinations greater than 10°
"
-%-
1 $ 1 +/1CA). 0 *"2B +/1 ). 1$1+/1C&).
Due to its historically poor performance, use of theSperry-Sun SRO tool is not recommended.
" $ # # D0& 0## $ $
BP AmocoBPA-D-004 Directional Survey Handbook
5-28 Survey Tools September 1999 Issue 1
" "
0+85' + 8 + "'"&5"+8'++ '"
1 #
Surface references must be established and checked by aqualified land surveyor, and recorded with a detailed stationdescription. The survey engineer on the rig must have a copyof this station description.
Drift corrections must be computed and appliedautomatically by software. Reliance on hand computationsby the survey engineer is not acceptable.
, -
/) 1 !
5--
" # " $ %
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-29
-%-
" 0 "
"
<5
" 9 7
Make sure a hard copy of the data is provided, withsufficient header data to ensure its traceability.
Insist on all data being labelled with the azimuth reference(magnetic, grid or true) and the correction, if any, applied.
Visually inspect the survey for spurious data points, oftenindicated by large dog-leg severities.
. /%%0%
'# 2 '# 1
BP AmocoBPA-D-004 Directional Survey Handbook
5-30 Survey Tools September 1999 Issue 1
/
# $ 6::4) 1 ( "
-#
# $ +. 1 E&C'
($6" <
#$ $ / ) $ 1 * E&C'
Engineers should seek advice from UTG beforeprogramming the Seeker tool in their wells.
*
"Finder1
Keeper"
Keeper’s L$ ( + . 63F
" " Finder $
Keeper E&C'
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-31
8
" 8 9 2 + *"2B. 6::464$><,=&(6>$><;=
-#
# D
'#(%&
# # $ +'A1'A11. ' "# ' 1
Engineers should seek advice from UTG beforeprogramming Camera-based gyro tools in their wells.
1 -
#$ /$ )
BP AmocoBPA-D-004 Directional Survey Handbook
5-32 Survey Tools September 1999 Issue 1
4--
5447'5"
" 0#" 7
• %
• 2 $
• A <
•
4 +5"
" 0# " / ) 2 (
# ( / ) %
<057=50+5"'
A
Where possible, the MWD engineer should keep his/her ownindependent depth tally, and seek to resolve any discrepancywith the driller’s tally.
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-33
-
5447'5"
1 7
• A +(FINDS.
•
A Battery/Memory 1GKeeper $ D 0#
<04 " '+4"
2 7 3<6H= +;.5<6H= +66. 63<>-= +6-. 9 ; 64444 3444
"
" %
"$ "
BP AmocoBPA-D-004 Directional Survey Handbook
5-34 Survey Tools September 1999 Issue 1
1 "
# # -3644" "
4 +5"
& ! &
#" / ) " " 63<6444 ( " $!
<057=50+5"'
" $! 1 E&C' 46Q 4-Q
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Survey Tools 5-35
# +%%&." D GGO /) GGO $ GGO
# ' " +. $
2 3+4
E&C' E& C' '# " E&C' % E&C' " '# D"A
'
2 E&C' ( " 7
• 2
•
BP AmocoBPA-D-004 Directional Survey Handbook
5-36 Survey Tools September 1999 Issue 1
•
• &
()
*
D E&C' $(
%+-/
E&C' C ' & 0 D"A
E&C' $
D E&C' " + .
BP
Am
ocoD
irectional Survey H
andbookB
PA
-D-004
Septem
ber 1999 Issue 1S
urvey Tools 5-37/38
ServiceCompany
JORPs document Tool Coverage Remarks
MWD Inertialgyro
North-seeking
gyro
Surfaceread-out
gyro
Camera-basedgyro
EMS Camera-based
magnetic
Tele-drift
Anadrill Anadrill MWD SurveyingProcedures Manual*
Anadrill internal proceduresdocument. Adopted asreplacement to obsolete MWDJORPs by BP Amoco.
Baker HughesINTEQ
JORPs for DirectionalMWD
BPX and BHI JORPs
Halliburton /Sperry-Sun
JORPs for SSDSDirectional MWD*
A separate documentdescribes Sperry-Sun’sInterpolation in-fieldreferencing service
Surface ReadoutGyroscope Operationsfor BPX
Covers the G2 and SRO gyros
Gyrodata BP JORPs Manual*
Scientific Drilling BP JORPs* Additional and complementaryto SORPs, SDC’s internalstandard.
Under revision at time of writing
Table 5.8 JORPs documents currently in use
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-i/ii
Section 6
Contents
Page
) @ 6-1
) +$5 6-2
) *4 6-6
) ! 6-8
) A 6-20
) ) 6-22
) , 4*+B 6-29
Figure
6.1 Generic failure mode and effects anal ysis formissed target and well collision 6-4
Table
6.1 Generic classification of potential failures in thedirectional and surve y process 6-5
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-1
) How to minimise the risk of a grosswell positioning error and establish anauditable trail from target definition todefinitive survey.
% & ' (
G 1 " G 1 <
'
) @
0 7
• #
•
"
BP AmocoBPA-D-004 Directional Survey Handbook
6-2 Technical Integrity September 1999 Issue 1
# 7
• + .
• + (/ ).
) +$5
" ( 9 $ 7
6 (
-
> % (
"/$) 7
• " / $) ( " /)
•
• " /) /$)
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-3
8%% **58 5
& 9 2# " # / ) $ + . 9 H6 ( 92# / ) /)
* ( " $
BP AmocoBPA-D-004 Directional Survey Handbook
6-4 Technical Integrity September 1999 Issue 1
gross surface location orsurvey error in drilled well
wrong well plan usedfor clearance scan
wrong input datafor clearance scan
wrong input to a/ctolerance calcs
clearance scanresults wrong
a/c tolerancecalculation error
a/c toleranceprint or plot error
a/c tolerance wrongor invalid on plan
inadequate surveyrunning or quality
procedures
tie-in or northreference error
survey running orquality procedures
mis-applied
unpredictablesurvey tool error
rig not at plannedlocation or elevation
change in targetapproach direction
survey programnot followed
target toleranceinvalidated while drilling
anti-collision toleranceinvalidated while drilling
wrong surface location orelevation used for planning
geological targetlocation or
boundary wronglydefined
clearance scansoftware error
inappropriate errormodel in drilled well
inappropriate error model in planned well
badly designed error model
inappropriate separation rule
badly designed separation rule
wrong input to targettolerance calculations
target tolerancecalculation error
target toleranceprint or plot error
target tolerance wrongor invalid on plan
target tolerance ignoredor misunderstood
a/c tolerance ignoredor misunderstood
drilling well plotting error
statistically extreme survey error
insufficient or inaccurate projection ahead of bit
gross survey error in drilling well
target toleraceviolated
a/c toleraceviolated
root-cause failure
knock-on effect
“on-design” event
Figure 6.1 Generic failure mode and effects analysis for missed target and well collision
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-5
'*48
" $ H6 "
A. DIRECTIONAL SOFTWARE / STANDARDS
1. Clearance scan software error
2. Badly designed error model
3. Badly designed separation rule
4. Target tolerance calculation error
5. Anti-Collision tolerance calculation error
B. DIRECTIONAL DATABASE
6. Missing data, surface location or survey error in drilled well
7. Inappropriate error model in drilled well
C. PLANNING DATA
8. Wrong surface location or elevation used for planning
9. Geological target location or boundary wrongly defined
D. DIRECTIONAL PLANNING
10. Wrong well plan used for clearance scan
11. Inappropriate error model in planned well
12. Inappropriate separation rule
13. Target tolerance printing/plotting error
14. Anti-Collision tolerance printing/plotting error
E. RIG POSITIONING
15. Rig not at planned location or elevation
F. SURVEY OPERATIONS
16. Survey program not followed
17. Inadequate survey running or quality procedures
18. Survey running or quality procedures mis-applied
19. Unpredictable survey tool error
G. DIRECTIONAL DRILLING OPERATIONS
20. Change in target approach direction
21. Target tolerance ignored or misunderstood
22. Anti-Collision tolerance ignored or misunderstood
23. Drilling well plotting error
24. Insufficient or inaccurate projection ahead of bit
25. Tie-in or north reference error
Table 6.1
Generic classificationof potential failures inthe directional andsurvey process
BP AmocoBPA-D-004 Directional Survey Handbook
6-6 Technical Integrity September 1999 Issue 1
) *4
" 0 ) " $ " 0 ( "
7%
" %O $ ) "7
• " +. A<A $ K$ $ $ "
• " $ G 1
• 1 < 1 2 2 (
• 1 < $ G 1
2 %" O
"%O 1 D"A 1B 1"
Section 3.1describes some of thetheory and techniquesof surface positioning
Appendix Cincludes an example
of a Well LocationMemorandum
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-7
84
< $ G 1 9 % ' $ " D% $
" $ $ 1 + , & + " 9 %' 1
8%'#%
* $$ 1R
D( $ % " $ # 9
Appendix Bincludes completedexamples of a FinalWell Position Memoand a final WellLocation Data Form
BP AmocoBPA-D-004 Directional Survey Handbook
6-8 Technical Integrity September 1999 Issue 1
) !
" $ " 7
• '
• 1
• C)
• %
• %$
& 0# $
8
" 9 $ $ "
" 9 ( $! )
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-9
'*8
" 9 ) " 7
• G O 1 ( #(G" $%' 1$#+.
& 7&'57(3 ';
• % ' D D $ ) %' + $ .
• D " D $ (
• '
+ 8 + "' 55
• %O +.
• % ' 1 1 ( #(G " D
&" 575""+0'"
• ' 9 ( D$ )
BP AmocoBPA-D-004 Directional Survey Handbook
6-10 Technical Integrity September 1999 Issue 1
• #,+;3=(66=. "
• 1 ' 1 1 ( #(G
• #$G 1 1 ( #(G
5"#'77"5"57=
• '( 1
•
• #" GC% + ,, G.
6 + &"5"57=
• # )
• ' 0
• G " % (
4 "5"
• C' 1 ( #(G
Section 4.2 hasdetails of the relief well
drilling contingencyrequirement
Section 4.2 hasdetails of this
calculation
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-11
'$
" $ $ 7
• #
•
•
6 &"#88506+=
"
1$ # # + D . ( " 1$ # ' #) 0 " 1$ # ' <
1$# 9
6 ; "80"5 "578+ '"57 &"
'6 'C"&
9 1$# <7
6 " "
BP AmocoBPA-D-004 Directional Survey Handbook
6-12 Technical Integrity September 1999 Issue 1
" 7
- "
> "
, #
3 #
H " $ $
5 " (
%'$
# $ % ' + . + (." 1$# < #
4+4 +53 '+=656 '++ '
0+85' D5+& "+=5"7'5"
• G 7
∗ " + %O 9 % ' $ .
Section 6.6discusses the
relationship betweendirectional databases.
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-13
∗ "
∗ " +J2 C"2 .
• G 9 (7
∗ G % '
∗ C
∗ G
• +. % ' $ "8 ! +J2C"2.
• G + . +.
0+; =4+&+5088' "" + '
5+& 5" 6 +& 7&'57
+ <0+ "
• 9
• % '
BP AmocoBPA-D-004 Directional Survey Handbook
6-14 Technical Integrity September 1999 Issue 1
• C + . 7
∗ "
∗ " + .
∗ # + ::Q:3Q:4Q D .
• % ' 9 2( 7
∗
∗ O "8
∗ O "8
∗ $
+C8+77"&5"0"0'' 807+ 7 8 77
"
• G
• G
D
Relief wellcontingency
requirements arein Section 4.2
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-15
5"=&+ +++" 5'60+; ="+0 "
77( '
• G " 7
∗ &
∗ G
∗ D + $% .
5"5 <05 8"; 0+; =77(
(5"
• G
56 + "' 5"#'77""+0'"77
4+ ; ";75"8"0 77 45+5"
+07
• G ( 7
∗ %
∗ #
∗ %
• G + .
BP AmocoBPA-D-004 Directional Survey Handbook
6-16 Technical Integrity September 1999 Issue 1
• G 7
∗ %
∗ %
• C $ "GC + .D 7
∗ "
∗ 9
• 9 7
∗ C
∗ G $ + .
• 9 $ 7
∗ #
∗ G
∗ G $ $
77 "+0'"5"+5"&5+ '7 5+D
5''0+5 5"088' "
• G " $
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-17
• G ) 7
∗ " $
∗ "
∗ " + .
∗ "
" ' 1 +.7
• +. $
• G 7
∗ "
∗ "
∗ " +" A .
∗ " + % ' 1 A1 +>-.
∗ " ! + .
• 1 1 +) .
BP AmocoBPA-D-004 Directional Survey Handbook
6-18 Technical Integrity September 1999 Issue 1
• G ) +.
• G + . +.
• G +.
'%#**
' 9 R % %'
% %' 1$# $( 9( $ $
% 1$ # 9 % 7
• " ' # 1$ #R
• "
• " 9
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-19
(05--
D 1$#D ( # + . 7
• " $ " %' 1
• "
• " < + .
4 "5"8++ ' " 4+5''
8 %& ' ( D " 0 0 D$ % 7
• " "
∗ C %
∗ '<1 " 9( 7
Appendix Ccontains an exampledispensation form
BP AmocoBPA-D-004 Directional Survey Handbook
6-20 Technical Integrity September 1999 Issue 1
∗ 1 ' < 1 " *
∗ C" (
∗ E #
∗ # G
• 2
• 1 D%
) A
G $$ " ( "
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-21
77 506+=75"
"
Certain rules (such as not crossing anti-collision tolerancelines and following JORPs) are inflexible.
1 + .
77 0+; =;575"
" "B# $ $ 1$ 7
When in doubt, re-survey.
65"7"&""#'"8+5"'
#$ ) *$ 7
• 9
• 9
• 1 $$
• 8 ( ($
BP AmocoBPA-D-004 Directional Survey Handbook
6-22 Technical Integrity September 1999 Issue 1
7
6 *$
-
> # )
, C 7
. # )
. 1 $
) )
8
" ( 1 (
" %19 " 7
• " + .
• #
Appendix Ccontains a
Non-ConformanceReport form suitable
for this
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-23
• B B#
• "
+-
" % "
# " % % $ #%
" 7
• "
• # +.
• 9 0#
•
• # %1B#1
Survey datacomparisons arediscussed inSection 4.10
BP AmocoBPA-D-004 Directional Survey Handbook
6-24 Technical Integrity September 1999 Issue 1
•
;%
# " ( " / )
9 ( " $ # )
"
unvalidated survey data should never be loaded on thedefinitive directional database
) " 9
" +,64. 9 B#
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-25
77 0+; =<56
" < " E&C' " '# %19
*
" ) " 1 ' 7
6 "
- "(%C' + $. )
> 1
, % # $ "$ + ,64. (
3 #
H 1 ( ) #(
BP AmocoStandard Practice
BP AmocoBPA-D-004 Directional Survey Handbook
6-26 Technical Integrity September 1999 Issue 1
40(76"&6 55
# $ $ %
/
" & ' $$ + --. " '#
55'+'57=
" # G ) 7
• 1 $ $
•
*( 7
•
• "
• C<<<
• 1
• '
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-27
9 7
•
• 8
• 0#
8"; 55(5
& ( % "
" 9 ( 1 1
* #
5'' + +'"
D 7
•
•
BP AmocoBPA-D-004 Directional Survey Handbook
6-28 Technical Integrity September 1999 Issue 1
% "
65+#'4=55(5'C#04
1) "
+ '"5755(5 '45+"
' $ '# " ( )
' # " ( # 2#' ' " 7
• %
• % + . -
• % + "8. 3
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-29
1 $
0 +;&75"'
% # ( $ " ( + ( .
) , 4*+B
% * $$ "
4 +8+5"' 50+
$ 1 / ) + D . # G
% < 1( 7
• '
∗ *
BP AmocoBPA-D-004 Directional Survey Handbook
6-30 Technical Integrity September 1999 Issue 1
∗ "$
∗ *$
• &
∗ 164444
∗ *
∗ *0#
•
∗ %
∗ "
∗ (
'6"'57"; &5"
& $$ #
2 # % 1 9 #
C"7 & (5
'# " 7
• JORPs
# E&C'
Calculation oftortuosity is explained
in Section A.6
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Technical Integrity 6-31/32
• Approved survey error models
" (
• This Handbook
" $$ 1 1 D"A % " 1 E&C'
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-i
Appendix A
+*
Contents
Page
5 '' A-1
5 4'% - A-3
5 ' A-8
5 ! 5' A-9
5 5#'' A-17
5 ) A-22
Figure
A.1 Reverse surve y calculation A-2
A.2 Geometrical construction of the pedal curve A-7
A.3 The pedal curve and uncertainties in thenorth and east directions A-7
A.4 Naming convention for sensor axes A-8
A.5 A ‘bit’s-e ye-view’ of the target: the basis of theBP Amoco target anal ysis method A-10
A.6 Graphical method of target anal ysis A-16
A.7 Calculating a no-go area on the travelling c ylinder diagram A-18
BP AmocoBPA-D-004 Directional Survey Handbook
A-ii Mathematical Reference September 1999 Issue 1
Appendix A
+*
Contents (cont’d)
A.8 Derivation of the risk-based separation rule A-20
A.9 Behaviour of the risk-based separation rule atlow positional uncertainty A-21
A.10 Behaviour of the risk-based separation rule atintermediate positional uncertainty A-21
A.11 Behaviour of the risk-based separation rule athigh positional uncertainty A-22
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-1
5--%A
5+*Some of the equations and formulaeunderlying the methods described inthe main part of the Handbook.
( (
5 '
'
" 7
[ ]∆∆
NMD
I A I A RF= +2 1 1 2 2sin cos sin cos .
[ ]∆ ∆E
MDI A I A RF= +
2 1 1 2 2sin sin sin sin .
[ ]∆ ∆V
MDI I RF= +
2 1 2cos cos .
C 9 RFDL
DL=
2
2tan
$
DL@+I I . I I S6+A A.T
"
BP AmocoBPA-D-004 Directional Survey Handbook
A-2 Mathematical Reference September 1999 Issue 1
"
RF@6DL ( X
( DL
( Y7
RFDL DL DL
= + + +112 120
17
20160
2 4 6
( XN446° YN6>° 6 64
5 68++ ; + 0+; ='57'075"
1 ! "
P0
P2
P1 u1
u2
u0
r01
r02
r12u12
u01
α12
C
u02
" ' ' ' + ."
' ( 7
u u u112
0201
01
0212= +
r
r
r
r
A similar method,also based on
interpolating the holedirection, can be
found in
World Oil, April 1986
Figure A.1
Reverse surveycalculation
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-3
' 7
( ) ( )u u u u u u u0 1 01 0 1 01 0 2 1 01 12 0221
22 2+ = ∠
= ∠ =cos cos .P CP P P P
( )u u u u u0 01 12 02 12= −.
O' ( )u u u u u2 12 01 02 12= −.
" + . 9 >
∆D r12 1212 12
2 2=
α αcsc α12
11 2= ×−sin u u
5 4'%
-
' $ >(> (7
> (@Cnev@σ σ σσ σ σσ σ σ
n ne nv
ne e ev
nv ev v
2
2
2
A (
BP AmocoBPA-D-004 Directional Survey Handbook
A-4 Mathematical Reference September 1999 Issue 1
*(#+*%5A
" $ ( + . " $ (+ $T$ $ (7
C T C Thla
h hl ha
hl l la
ha la a
hla nev hlaT=
=σ σ σσ σ σσ σ σ
2
2
2
Thla
I A I A I
A A
I A I A I
=−
−
cos cos cos sin sin
sin cos
sin cos sin sin cos
0
#IA !
6E40
" ! 7 + . ! $ +. + . +.
0"' +5"=854""6 77
" > ! " - (7
Cne@σ σσ σ
n ne
ne e
2
2
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-5
0"' +5"=55&; "; +'57 46
" $ $ > ( (7
C T C Tnen ne
ne ene nev ne
T** *
* ** *=
=σ σσ σ
2
2
TneI A
I A* tan cos
tan sin=
−−
1
0
0
1
'57'075"86+F"57 +++ 774
" ! 7
1$ (@σmax@( )σ σ σ σ σn e n e ne
2 2 2 2 2 24
2
+ + − +
1$ (@σmin @( )σ σ σ σ σn e n e ne
2 2 2 2 2 24
2
+ − − +
" ! (ψ ψ 7
tan222 2ψσ
σ σ=
−ne
n e$:4° P:4°
" 7
σ σn e2 2> $,3°Nψ majNP,3°
σ σn e2 2< $,3°Nψ min NP,3°
"
( Cne* (
BP AmocoBPA-D-004 Directional Survey Handbook
A-6 Mathematical Reference September 1999 Issue 1
'*%7* -% -%
" >, +- . " ( > /G0 1") /G0 *8) 2( % G$1 7
χ νp,2 p
ν χ νp,2 $
+ν @-.+ν @>.
p.
Example. Find the number of standard deviations at which a 3D error ellipsoidmust be drawn to represent a 95% confidence region, assuming the well positionerrors follow a trivariate normal distribution.
Setting p = 0.95 and ν = 3, we find from tables that χ0 952. ,3 = 7.81. The 95%
confidence region is therefore represented by a 2.79-sigma error ellipsoid.
4%'98-:
" ! !#7
[ ]σσ σσ σ
σ σ σAn ne
ne en ne eA A
A
AA A A=
= + +cos sin
cos
sincos sin sin
2
22 2 22
" # ( /) $ 9#-
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-7
pedal curve
standarderror
ellipse
9 #> + .
standarderrorellipse
North
East
pedal curveor
“footprint”
σnorth
σeast
Figure A.2
Geometricalconstruction of thepedal curve
Figure A.3
The pedal curve anduncertainties in thenorth and eastdirections
BP AmocoBPA-D-004 Directional Survey Handbook
A-8 Mathematical Reference September 1999 Issue 1
5 '
* % + 1. " 7
Y-axis
X-axis
Z-axis(down hole)
GravityHighside
τ
τ = instrument toolface angle
" Gx, Gy, Gz
Bx, By, Bz + . ! 7
Inclination = I =cos−
+ +
12 2 2
G
G G G
z
x y z
sin−+
+ +
12 2
2 2 2
G G
G G G
x y
x y z
Magnetic Azimuth = Am = ( )( ) ( )tan−
− + +
+ − +
12 2 2
2 2
G B G B G G G
B G G G G B G B
x y y x x y z
z x y z x x y y
Instrument toolface = τ = tan−
1 G
Gx
y
Figure A.4
Naming conventionfor sensor axes
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-9
" 7
G G Ix = − sin sinτ
G G Iy = − sin cosτ
Gz@GI
B B I A B I B Ax m m= − +cos cos cos sin sin sin sin cos sin cosΘ Θ Θτ τ τ
B B I A B I B Ay m m= − −cos cos cos cos sin sin cos cos sin sinΘ Θ Θτ τ τ
B B I A B Iz m= +cos sin cos sin cosΘ Θ
G, B Θ
" 7
Gravity Field Intensity@ G G Gx y z2 2 2+ +
Magnetic Field Intensity@ B B Bx y z2 2 2+ +
Magnetic Dip Angle@sin.
− + +
1
G B G B G B
G Bx x y y z z
5 ! 5'
" ) "'# " !
BP AmocoBPA-D-004 Directional Survey Handbook
A-10 Mathematical Reference September 1999 Issue 1
(45%
A ( + . "
Vi
Ui
Xi
Yiσh
σl l ij
hijφij
φi+1
φi+1− φi
NsPX
PY
b
Exclusion probability is integratedover the part of each sector
lying outside the target...
…then summedover all sectors
geological targetreference point
geological targetboundary
standard errorellipse
φi
as-surveyed pointof penetration
1 +! .δ ! + !$.α K$ ( ! ! α − °90 M$ ($
Figure A.5
A ‘bit’s-eye-view’ ofthe target: the basis of
the BP Amoco targetanalysis method
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-11
1 Nv
$ Xi Yi xii
i
X
Y=
1 $
p =
P
PX
Y
$ ( +
. $b
9(:# = ; :86 5+& (0"5+=
" (x pi −
" $ +*28.$ (
Ttp = −−−
−
sin
cos
cos cos
sin cos
sin
αα
δ αα δ
δ0
# ( (
( )T x p btp i − +
9 (
TtcI A
A
I A
A
I=
−−
cos cos
sin
cos sin
cos
sin
0
( ( $ 7
( )[ ]U
V
highside
laterali
itc tp i
=
= − +T T x p b
BP AmocoBPA-D-004 Directional Survey Handbook
A-12 Mathematical Reference September 1999 Issue 1
4886 +0 (4"
"( +. $ ( " ( $ 7
C T C Ttch hl
hl ltc nev tc
T=
=
σ σσ σ
2
2
( )( )
pdftc
Ttc
tC
t C t= −
−1
2
1
21
π detexp
( )=−
− + −−
1
2
2
22 2 2
2 2 2 2
2 2 2π σ σ σσ σ σ
σ σ σh l hl
l hl h
h l hl
h hl lexp
t =
h
l
"'70"4+(5(7=
"
h
l
r
r
→
cos
sin
φφ
( ) ( )( ) ( )( )
pdf r r fh l
rh l hl
, exp det,
,φ
π σ σ σφ
∂∂ φ
=−
−
1
2 2 2 2
2
( )( )=−
−rr f
h l hl2 2 2 2
2
π σ σ σφexp
( ) ( )f l hl h
h l hl
φ σ φ σ φ σ φσ σ σ
= − +−
2 2 2 2
2 2 2
2
2
cos sin sin
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-13
Ns
( 7
( )
( )
I pdf r d drij
jN
jN
r h l
r
ii i
s
ii i
s
ij ij
≈
= + −
−
= +−
= +
=∞
+
+
∫∫ ,φ φ
φ φφ φ
φ φφ φ
1 1
1
2 2
h
lij
ij
$
(
$ φii
i
U
V=
−tan 1
( ( $ (
( $
( )IN
pdf r driji i
sij
r h l
r
ij ij
≈−+
= +
=∞
∫φ φφ1
2 2
,
φ φ φ φij i
i i
s
jN
= + −
−+1
21
" ( 7
( )( )IN
r r f driji i
s h l hlij
r h l
r
ij ij
=−
−−+
= +
=∞
∫φ φ
π σ σ σφ1
2 2 221
22 2
exp
BP AmocoBPA-D-004 Directional Survey Handbook
A-14 Mathematical Reference September 1999 Issue 1
( )( )( )=
−
−
− −
+
= +
=∞φ φ
π σ σ σ
φ
φi i
s h l hl
ij
ijr h l
r
N
r f
fij ij
12 2 2
21
2 22 2
exp
( ) ( ) ( )
= − − +
−+φ φ φ
π φ σ σ σi i
s
ij ij ij
ij h l hlN
h l f
f
1
2 2
2 2 24
exp
" h lij ij2 2+
h
lij
ij
7
+ . $7 h l ij= tanφ
+. i 7 l V
h U
V V
U Ui
i
i i
i i
−−
= −−
+
+
1
1
1l ( ) ( )( ) ( )
lV U U U V V
U U V Viji i i i i i
i i i i ij
=− − −
− − −+ +
+ +
1 1
1 1 tanφ
( ) ( )( ) ( )
h l l ll V U U U V V
U U V Vij ij ij ij ijij
ij
i i i i i i
i i ij i i ij
2 2 2 2 22
21 1
1 1
2
+ = + = =− − −
− − −
+ +
+ +tan
cos cos sinφ
φ φ φ
" ( 7
p @ ( )1
11
−==
∑∑ I ij
j
N
i
N sv
p
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-15
&-%
" ) ! " ( :;Q+ ) :;Q. 9 (
4
G $ +bH σ H .
+bL σ L .1
! A
4
4
* !
( )2σ H Hb Inc− cos ! A
Inc
4!
!
( )2σ H Hb Inc+ cos !AP6;4F
4
!
2σ L Lb− !AP:4F
4)
!
2σ L Lb+ !A$:4F
BP AmocoBPA-D-004 Directional Survey Handbook
A-16 Mathematical Reference September 1999 Issue 1
4,
" ) 9#H (
planned wellazimuth, A
2σH - bH
2σL - bL2σH + bH
2σL + bL
geological targetdriller’s targetstep 3
step 5
step 4
step 6
cos Inc
cos Inc
Figure A.6
Graphical method oftarget analysis
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-17
5 5#''
-'
0+85' 4"0"' +5"=
" 7
σ σ σ22 2= +surf hole
σsurf @ C
6
σhole @
+ . 6
5775"' 8+0+; =(5
" # ( + . = =+ ."( 7
Sb @MaxU4+$
.V
@
@
BP AmocoBPA-D-004 Directional Survey Handbook
A-18 Mathematical Reference September 1999 Issue 1
* + $
. + .
'*"#&5
" $ β
+ 6- ) . 7
. >$ 7
@
( ) ( )( ) ( )
( )
cos cos cos sin sin
cos sin cos cos sin
sin cos
I A A A A
I A A A A
I A
β ββ β
β
− − −− + −
− −
7
I @ "G
A@ #! "G
β u
interfering well
no-goarea
0
minimumallowableseparation
Figure A.7
Calculating a no-goarea on the travelling
cylinder diagram
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-19
. 7
σ1@ u C uT1
σ2 @ u C uTsurf22+ σ
7
C1 @ ' (
C2 @ (
σ surf @ C
6
. +,>.
+$#(%-+
" $
Sd d
P
d d=
+
++
σσ π
22 2
1 2 1 2ln
" G 9#; OS $$ σ R + . % z7
( )f z
z S( ) exp= −
−
1
2 2
2
2σ π σ
BP AmocoBPA-D-004 Directional Survey Handbook
A-20 Mathematical Reference September 1999 Issue 1
#
( )P f z dz
d d
d d
=
−+
+
∫1 2
1 2
2
2
+ #;. % ( + $ .1
( ) ( )[ ]P d d f
d d d d S d d≈ +
+
=
+−
− +
1 2
1 2 1 2 1 22
22 2
2
2σ π σexp
/
S (
S
z = 0
z =
d1d2
d1 d2+
2d1 d2+
2z =_
z = S
σ
f(z)
interferingwell
plannedwell
" ( # (
Figure A.8
Derivation ofthe risk-based
separation rule
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-21
% + 6.
Collision Risk (low position uncertainty)
Collision Risk (higher position uncertainty)
σaσb SaSb
Tolerable Collision Risk
Actual Collision Risk
Minimum Separationincreases as Combined
Position Uncertainty increases
Case 1
d + d1 2
Pσ < 0.242
# + -. "
ab
σaσb
SS
Tolerable Collision Risk
Minimum Separationdecreases as Combined
Position Uncertainty increases
Case 2
d + d1 2
P > σ > 0.242
d + d1 2
P0.399
2 ( + >.
Figure A.9
Behaviour of therisk-based separationrule at low positionaluncertainty
Figure A.10
Behaviour of therisk-based separationrule at intermediatepositional uncertainty
BP AmocoBPA-D-004 Directional Survey Handbook
A-22 Mathematical Reference September 1999 Issue 1
σaσb Sa
Tolerable Collision Risk
Tolerable Collision Risk isnever exceeded - no
Minimum Separation exists
Case 3
d + d1 2
P σ > 0.399
5 )
"D"A
the average excess dogleg severity over plan
# " DTD +
D0."
!7
[ ]D I A i MPi
Pi
Pi 0 ≤ ≤
$
[ ]D I A j NSj
Sj
Sj 0 ≤ ≤
Figure A.11
Behaviour of therisk-based separationrule at high positional
uncertainty
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Mathematical Reference A-23/24
9 +#6. 7
( ) ( )[ ] DL I I I I A APi
Pi
Pi
Pi
Pi
Pi
Pi= − − − −− − − −cos cos sin sin cos1 1 1 11
7
DLSD D
DLPTD
Pi
i
M
=− =
∑1
0 1
O $7
DLSD D
DLSTD
Sj
j
N
=− =
∑1
0 1
( ) ( )[ ] DL I I I I A ASj
Sj
Sj
Sj
Sj
Sj
Sj= − − − −− − − −cos cos sin sin cos1 1 1 11
" 7
Wellbore Tortuosity = DLS DLSS P−
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Approved Tool Error Models B-i/ii
Appendix B
Contents
Page
!
"#$% &
$' (
&
' )
*
' +
(
,
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Approved Tool Error Models B-1
An inventory of the survey tool error modelsapproved for use in BP Amoco.
! ""#$%
&
• ' (
• ( )#
• ( ) * #+
The standardformat for surveytool error modelsis described in
BP
Am
ocoB
PA
-D-004
Directional S
urvey Handbook
B-2 A
pproved Tool E
rror Models
Septem
ber 1999 Issue 1
MWD - Standard MWD MWD MWD with no (or no known) specialcorrections
The model allows for the fact that axialinterference may marginally exceed the upperlimit specified in Section 4.9 when the well isnear to horizontal east/west
MWD + Sag correction MWD+SAG MWD+SG MWD with a BHA deformationcorrection applied
Covers all BHA corrections, from simple 2D tofinite-element 3D models
MWD + Short Collar correction MWD+SCC MWD+SC MWD with single station axialinterference correction applied( 4.9)
“Short Collar” is the name of Sperry-Sun’scorrection, but the error model covers all such
MWD + Sag + SC corrections MWD+SAG+SC MWD+SS MWD with both BHA sag correctionand single station axial interferencecorrection applied
MWD + IHR correction MWD+IHR MWDIHR In-hole referenced MWD ( 4.8). Assumes a BHA sag correction is applied toenhance inclination accuracy
MWD + IFR correction MWD+IFR MWDIFR In-field referenced MWD ( 4.7),with time-varying field applied. Modelis applicable whether or not ShortCollar type correction is applied.
Assumes a BHA sag correction is applied toenhance inclination accuracy.
Table B.1 Approved Survey Tool Error Models – MWD (Part 1 of 2)
BP
Am
ocoD
irectional Survey H
andbookB
PA
-D-004
Septem
ber 1999 Issue 1A
pproved Tool E
rror Models B
-3
MWD + IFR [Alaska] MWD+IFR:AK MWDIAK In-field referenced MWD in Alaska Model takes account of increased violenceof magnetic field disturbances in Alaska.Assumes a BHA sag correction is appliedto enhance inclination accuracy
MWD + IFR [ Wytch Farm] MWD+IFR:WF MWDIWF In-field referenced MWD at WytchFarm
Model takes account of observed lowlevels of axial low level interference usingAnadrill BHA components and design.Assumes a sag correction is applied toenhance inclination accuracy
MWD + IFR + Multi-station MWD+IFR+MS MWDIMS In-field referenced MWD with multi-station analysis and correction( 4.9) applied in post-processing
Assumes a BHA sag correction is appliedto enhance inclination accuracy
MWD + Crustal Anomaly corrn MWD+crust MWD+CA MWD where local magnetic field hasbeen measured (or derived fromaero-magnetic data) and correctedfor, but short-term time variations arenot applied.
Assumes a BHA sag correction is appliedto enhance inclination accuracy
MWD + Crustal + SC corrections MWD+CA+SC MWD+CS Same as MWD + Crustal Anomalycorrection but with single station axialinterference correction applied
Assumes a BHA sag correction is appliedto enhance inclination accuracy
Table B.1 Approved Survey Tool Error Models – MWD (Part 2 of 2)
BP
Am
ocoB
PA
-D-004
Directional S
urvey Handbook
B-4 A
pproved Tool E
rror Models
Septem
ber 1999 Issue 1
EMS - Standard EMS EMS Electronic multishot with no (or noknown) special corrections
Includes ex-BP “Electronic Single Shots”model. Assumes large axial interferenceerrors have been corrected.
EMS + Sag correction EMS+SAG EMS+SG Electronic multishot with a BHAdeformation correction applied
Covers all BHA corrections, from simple 2D tofinite-element 3D models. Assumes large axialinterference errors have been corrected.
EMS + IHR correction EMS+IHR EMSIHR In-hole referenced electronicmultishot ( 4.8).
Assumes a BHA sag correction is applied toenhance inclination accuracy.
EMS + IFR correction EMS+IFR EMSIFR In-field referenced electronicmultishot ( 4.7), with time-varyingfield applied. Model is applicablewhether or not Short Collar typecorrection is applied.
Assumes a BHA sag correction is applied toenhance inclination accuracy.
EMS + IFR [Alaska] EMS+IFR:AK EMSIAK In-field referenced electronic inAlaska
Model takes account of increased violence ofmagnetic field disturbances in Alaska.Assumes a BHA sag correction is applied toenhance inclination accuracy
EMS + Crustal Anomaly corrn EMS+crust EMS+CA Electronic multishot where localmagnetic field has been measured(or derived from aero-magnetic data)and corrected for, but short-term timevariations are not applied.
Assumes large axial interference errors havebeen corrected.
Table B.2 Approved Survey Tool Error Models - Electronic Magnetic Multishots
BP
Am
ocoD
irectional Survey H
andbookB
PA
-D-004
Septem
ber 1999 Issue 1A
pproved Tool E
rror Models B
-5
BHI RIGS multishot RIGS RIGS INTEQ RIGS multishot surveys
BHI Seeker multishot Seeker MS SKR MS All INTEQ Seeker ( 5.8) multishotsurveys
Ferranti FINDS multishot FINDS FINDS All Ferranti FINDS ( 5.8) surveys
Gyrodata - gyrocompassing m/s GYD GC MS GYD GC Older Gyrodata gyro multishots, plusall battery/memory tool surveys(RGS-BT)
Replaces ex-BP “Gyrodata multishot intoopen hole” model.
Gyrodata - cont. casing m/s GYD CT CMS GYD CC Gyrodata multishot surveys withcontinuous tool (RGS-CT) in casing.OD 13-3/8” or less.
Gyrodata - cont. drillpipe m/s GYD CT DMS GYD CD Gyrodata pump-down multishotsurveys with continuous tool (RGS-CT) in drill-pipe.
Gyrodata - large ID casing m/s GYD LID MS GYD LC Gyrodata multishot surveys(gyrocompassing or continuous tool)in larger size casing strings (greaterthan 13-3/8” OD).
Includes an increased misalignment term
Gyrodata – bat/ mem drop m/s GYD BM MS GYD BM Gyrodata multishot usingBattery/Memory tool in anyconfiguration.
Table B.3 Approved Survey Tool Error Models - North Seeking and Inertial Gyro Multishots (Part 1 of 2)
BP
Am
ocoB
PA
-D-004
Directional S
urvey Handbook
B-6 A
pproved Tool E
rror Models
Septem
ber 1999 Issue 1
Schlumberger GCT multishot GCT MS GCT GCT surveys in casing or open hole. GCT = “Gyro Continuous Tool” ( 5.8)
SDC Finder - multishot Finder MS FDR MS Finder multishots in casing or drillpipe
Replaces ex-BP “Inrun” and “Outrun” models
SDC Keeper - casing m/s KPR csg MS KPR CM Keeper multishot surveys in casing.OD 13-3/8” or less.
SDC Keeper - drillpipe m/s KPR d/p MS KPR DP Keeper pump-down multishot surveysin drill-pipe.
SDC Keeper - large ID csg m/s KPR LID MS KPR LC Keeper multishot surveys in largersize casing strings (greater than13-3/8” OD).
Includes an increased misalignment term
Sperry-Sun G2 multishot G2 gyro MS G2 MS G2 ( 5.8) multishots in casing, drillpipe or open hole
Replaces ex-BP “Static” and “Dynamic”models
Table B.3 Approved Survey Tool Error Models - North Seeking and Inertial Gyro Multishots (Part 2 of 2)
BP
Am
ocoD
irectional Survey H
andbookB
PA
-D-004
Septem
ber 1999 Issue 1A
pproved Tool E
rror Models B
-7
Inclinometer ( Totco/ Teledrift) INC INC Inclination only surveys in near-vertical hole, including TOTCO,Teledrift and Anderdrift.
Inclinometer + known azi trend INC+trend INC+TR Inclination only surveys in near-vertical hole, where formation dip andexperience enables direction of driftto be predicted.
Replaces ex-BP “Inclinometer (azimuth inknown quadrant)” model
Table B.4 Approved Survey Tool Error Models - Inclination Only Surveys
BP
Am
ocoB
PA
-D-004
Directional S
urvey Handbook
B-8 A
pproved Tool E
rror Models
Septem
ber 1999 Issue 1
Camera-based mag single shot CB mag SS CBM SS Traditional (mechanical) magneticsingle shot ( 5.5)
Assumes tandem probes are run and thatboth are adequately magnetically spaced.Replaces ex-BP “PMSS”.
Conventional SRG single shots SRG SRG Optically-referenced gyro single shots( 5.6) Includes SDC Keeper whenused in “siteline reference mode”.
Tool types include SRG and MSRG(scientific Drilling), Sigma (INTEQ) andSRO (Sperry-Sun).
Camera-based gyro single shots CB gyro SS CBG SS Traditional surface referenced gyrotool run on wireline, including “levelrotor” gyros and Sperry-Sun SU3.
Replaces ex-BP “PGSS” model.
Gyrodata - gyro single shots GYD SS GYD SS Gyrodata gyro orientation surveys
SDC Keeper - gyro single shots KPR SS KPR SS Keeper gyro orientation surveys Excludes siteline (ie. surface) referencedsurveys
SDC Keeper – surface ref s/s KPR SR SS KPR SR Keeper gyro orientation surveys,where azimuth alignment is achievedby optical referencing at surface.
SDC Finder - gyro single shots Finder SS FDR SS Finder gyro orientation surveys
NS Gyro single shots NS gyro SS NSG SS North seeking gyro orientationsurveys taken with unspecified tool.
Note Gyrodata, SDC Keeper and SDCFinder have their own models, whichshould be used if the tool type is known tobe one of these.
Table B.5 Approved Survey Tool Error Models - Other Single Shot Types
BP
Am
ocoD
irectional Survey H
andbookB
PA
-D-004
Septem
ber 1999 Issue 1A
pproved Tool E
rror Models B
-9
Camera-based gyro multishot CB gyro MS CBG MS Traditional optically referenced gyrosurveys run on wireline, including“level rotor” gyros and Sperry-SunSU3 ( 5.8).
Replaces ex-BP “PGMS” model.
Camera-based magnetic multishot CB mag MS CBM MS Traditional (mechanical) magneticmultishot ( 5.5)
Assumes adequate magnetic spacing.Replaces ex-BP “PMMS”.
Dipmeter or other wireline log Dipmeter DIPMTR Wireline conveyed logging tools withdirectional survey capability ( 5.7).
Schlumberger OBDT, BGT are examples
Sperry-Sun BOSS gyro multishot BOSS gyro BOSS Sperry-Sun BOSS multishot surveys( 5.8).
Table B.6 Approved Survey Tool Error Models - Other Multishot Types
BP
Am
ocoB
PA
-D-004
Directional S
urvey Handbook
B-10 A
pproved Tool E
rror Models
Septem
ber 1999 Issue 1
Blind drilling Blind n/a Hole intervals where no surveys aretaken
Model assumes well direction deviatesfrom last known survey at a constant rate.Errors grow with square of distance drilled.
Unknown survey Unknown n/a Any survey data of unknown ordubious type
Replaces ex-BP “unknown multishot”model.
Zero Error model Zero Error n/a Used to set position uncertainty tozero down to a given depth (eg. side-track point).
Table B.7 Approved Survey Tool Error Models - Special Models
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-i/ii
Appendix C
Contents
Page
C-5
C-8
C-9
C-10
C-12
C-14
C-16
! C-18
" #" ! C-20
$ % ! C-22
&% ! ' C-27
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-1
(
Checklists and proformas to facilitateauditability and quality assurance.
!! "#$%& # '(&' )* & +% , + ,
# )* ! ' ) "
#
BP AmocoBPA-D-004 Directional Survey Handbook
C-2 Data and Work Sheets September 1999 Issue 1
)*$*")*!"+
# - # #
")*$*")*,*)$))-).
& ! - #
")*$*"$*!,*)$)
)-).
$ . $*!/ - - #
# ! 0 % * # - .12/
!)$*")/"$&))$
3 )" #
The function ofthe Well LocationMemorandum is
discussed in moredetail in Section 6.3
DGPS and othersurface positioning
systems aredescribed inSection 3.1
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-3
!)$*")/"&)0$
%* 0 - 4.56/
+!1)2!*/!$&))$
3 ! 4 % ! 4 %*
"$**""$!+$*"&))$
- 7 - # 3 0! 4 %*
)"$*"!*!)*)")!$)
$ 8 # % *
"*"*")##"*"*"*!")!)*!$
7 & 9
1 8 .+'-,/
: .+'-,/
& - . 5;/ 4%!4
BP AmocoBPA-D-004 Directional Survey Handbook
C-4 Data and Work Sheets September 1999 Issue 1
*
$*)!3)**"!0*!0&))$
" - 0 . 62 66/< -
!)$*"+!1)2&"3**0&"/)!)4+)$
" = 8# 8
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-5
WELL LOCATION MEMORANDUM
LOCATION DESIGNATION
This WLM supersedes the following previous locations:
(NB: Any change in shotpoint location must have a new location designation)
Country: Prospect/Field:
Region/State: Lease/PSC/Block:
1. WELL LOCATION DEFINITION (To be completed by Buisiness Unit subsurface and/or reservoir team)
SURFACE LOCATION:PRIMARY DEFINITION: 3D, 2D, HR Seismic Survey or OTHER* (* Circle appropriate definition)
Survey name: Survey mnemonic:
3D Inline bin, orDatabase type & name: 2D/HR line number:
3D Xline bin, orAcquisition contractor & year: 2D/HR shot number:
3D bin size (Inline x Xline):Processing contractor & year: or 2D/HR shotpoint interval:
OTHER DEFINITION (eg: template & slot No.):
SECONDARY DEFINITION: 3D, 2D or HR* Seismic Survey (* Circle appropriate definition)
Survey name: Survey mnemonic:
3D Inline bin, orDatabase type & name: 2D/HR line number:
3D Xline bin, orAcquisition contractor & year: 2D/HR shot number:
3D bin size (Inline x Xline):Processing contractor & year: or 2D/HR shotpoint interval:
PRIMARY DRILLING TARGET LOCATION (for non-vertical wells):
PRIMARY DEFINITION: 3D, 2D or HR* Seismic Survey (* Circle appropriate definition)
Survey name: Survey mnemonic:
3D Inline bin, orDatabase type & name: 2D/HR line number:
3D Xline bin, orAcquisition contractor & year: 2D/HR shot number:
3D bin size (Inline x Xline):Processing contractor & year: or 2D/HR shotpoint interval:
Section 1 completed by: Section 1 approved by:
Signature: Signature:
Date: Date:
Name: Name:
Position/Job Title: Position/Job Title:
BP AmocoBPA-D-004 Directional Survey Handbook
C-6 Data and Work Sheets September 1999 Issue 1
Well Location Memorandum - Page 2 LOCATION DESIGNATION
2. SUBSURFACE DATA (To be completed by Business Unit Subsurface Team)Attach a separate map sheet to this WLM showing seismic lines and geological structure around target location
Describe below in words and diagramatically the surface location and it's constraints (give dimensions):
Proposed Location
TOLERANCE Define Surface Location Tolerance(s)
Surface Location Area Diagram
Illustrate shape and size of the zone within which a surface location
would be acceptable and indicate constraints which limit rig
anchoring or manoevring (eg: shallow gas, obstructions, pipelines).
For location(s) derived from workstation provide:Coordinates of surface and primary target locations and two other bins remote from the primary target
(one bin with same Inline and one with same Xline bin number as primary target)
Location 3D Survey Name Bin Size Inline Xline Eastings Northings
Surface:
Primary Target:
Same Inline:
Same Xline:
For surface and target locations based on 2D or HR seismic provide:
Location 2D/HR Survey Name Point* Line No. Shotpoint Eastings Northings
Surface:
Primary Target:
* Mapped point type (SP, CDP, etc)
Attach extract of relevant 2D and/or HR line from database listing shotpoint coordinates values for
2km either side of proposed location
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-7
Well Location Memorandum - Page 3 LOCATION DESIGNATION
3. WELL LOCATION COORDINATES (To be completed by UTG SURVEY GROUP)
LOCATION COORDINATES
SURFACE LOCATION (Vertical or Deviated well) PRIMARY TARGET L OCATION (Deviated well)
Latitude: Latitude:
Longitude: Longitude:
Eastings: Eastings:
Northings: Northings:
Surface Positioning Tolerance: True azimuth from surface location: degrees
Water depth: Horizontal offset distance: m ft
Ground Elevation:
Geodetic Information:
Datum name: Datum mnemonic:
Ellipsoid name: Ellipsoid mnemonic:
Projection name: Projection mnemonic: Zone:
Data source of coordinates (eg: database name, report, etc):
Surface Location:
Primary Target Location:
Seismic survey positioning systems and horizontal accuracy estimates:Surface Location Primary Target Location
Positioning System Accuracy Positioning System Accuracy
3D Seismic:
2D Seismic:
HR Seismic:
Other positioning information:
Section 3 completed by: Section 3 approved by:
Signature: Signature:
Date: Date:
Name: Name:
Position/Job Title: Position/Job Title:
Circulation:
D.S. / S.D.E. / D.E. Site Investigation Specialist
Subsurface Team Leader Data Administrator (load to database)
Asset Geoscientists Head of Survey
BP AmocoBPA-D-004 Directional Survey Handbook
C-8 Data and Work Sheets September 1999 Issue 1
")*$*")*)-)
! " # # $%&'$%(#%)* ##%+,
!"
" #$ %& '(%)* +,- . /0%( 1
2 " ($ -& --'0)
2 " (0 %'# +34 5 64 $ 1
*2 " # #70 %/' *
'8# 2 ('78$ %(9%:/ + #1'
; < !' /
! '%- '
! '
(#'-$ (-'-$
=9: ,2
2 ! -'-° '
-. )+/ "- !0 !
12+ !0 ! 0 . 3" 4.
#) 2 2 =9: '%
2 2 ! /'- '
: 2
6 > '
0 5 6 4
?' %-78
, " 4 /007
!"
##$$ %%& $
'()
BP
Am
ocoD
irectional Survey H
andbookB
PA
-D-004
Septem
ber 1999 Issue 1D
ata and Work S
heets C-9
Country: Area: Well Number:
Prospect/Field: Submit to BP Amoco Survey for checking/approval Location designation:
Date Completed:
Accepted Sur face Pos i t i on Secondary Positioning System Contractors report no.
(Geogs: 2 dec places, Grid: 1 dp (m) 0 dp (ft)) (Geogs: 3 dec places, Grid: 2 dec places) Geodetic ParametersLat: ° Long: °
Geodetic Datum Projection and zone: ! Ref.Stn.1: Name/Country: Associated Ellipsoid "!#!#$ !%
Easting: && Northing: & & Lat. Long. Semi-major axis & '
Radius of error: ( ' Primary Positioning System Easting Northing Semi-minor axis(Geogs: 3 dec places, Grid: 2 dec places) Dist to Ref.Stn. km Reciprocal flattening 1/
System/method for Names of Reference Station(s) used for Ref.Stn.2: Name/Country: Datum Shiftaccepted position )*+$, -. Primary Position Lat. Long. From WGS84 to Local Datum
Easting Northing dX: ' dY: ' dZ: ( 'Secondary positioning Dist to Ref.Stn. km rX: rY: rZ: (&
system: %#+$, -. Antenna Position: WGS84 Datum Ref.Stn.3: Name/Country: Scale Factor: //'
Lat: ° Lat. Long. Useful Information / Notes
Rig positioning contractor: 0112 Long: ° Easting NorthingJob number: Sph. Ht. Dist to Ref.Stn. km 3$4 + ' '/$%5 6* 7 83 9$%%$'4 ! 4 !
Site survey date: Antenna Coords: Network Solution $%% 4##$ ! + #3 $#$ !% :*
Contractor: Offset: Antenna to rotary WGS84 Datum 7!56 ) # %% 5$!#4 43 ;! Report number: (Relative range/bearing) Lat. ° correct.
Rig name: ! 0 3 & ' < ° Long ° Sph.Ht.Coords of rotary: Local Datum
Type of rig: Lat: ° S.D. X: Y: Z:
Vertical datum: Long: ° & Offset: Antenna to rotary (Rel. range/bearing)
! 2:% Ellip. Ht. ' < ° B.M.S.L. Easting: && Coords of rotary: Local Datum
Water or stated ' Northing: & & Lat. ° depth Vert Datum Long °
B.L.A.T. ' S.D. X: Y: Z: Easting: & S.D.RTE A.M.S.L && ' Northing & & S.D.
Diagram Diagram
Rig Hdg309.7 deg T
R/T
1.0
m
56.3 m
GPS Antenna
Rig Hdg309.7 deg T
R/T
17.4
m
42.55 m
GPS AntennaCompleted by:(block caps) 1"7
Checked by:(block caps) =>
BP AmocoBPA-D-004 Directional Survey Handbook
C-10 Data and Work Sheets September 1999 Issue 1
WELL PLAN DATA SHEET * delete as appropriate
Rig / Platform / Drill Site* Well
Sheet completed by Date
SURFACE LOCATION planned / actual* Datum/Ellipsoid Projection
Structure reference DescriptionLat. N / S* EastingLong. E / W* Northing
Well reference point DescriptionLat. N / S* EastingLong. E / W* NorthingOffset from structure ref. N / S* E / W*
Elevation (land rig) Elevation (offshore)Drill datum RT / KB* Drill datum RT / KB*Drill datum to well ref. pt. Drill datum to MSLWell ref. pt. to MSL Drill datum to well ref. pt.
TARGET #1 TARGET #2 TARGET #3Name Name NameEasting Easting EastingNorthing Northing NorthingDepth TVDss Depth TVDss Depth TVDssTolerance Tolerance Tolerance
Survey reference True / Grid* North arrows (diag.)Grid convergence (T to G) E / W*Magnetic declination (T to M) E / W*Magnetic model DateCorrection (magnetic to survey ref.)Correction (true to survey ref.)
Curved conductorsDrill datum to well reference point
MD TVD North EastN / S* E / W*
Incl. at w.r.p. Azim at w.r.p.
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-11
WELL PLAN DATA SHEET * delete as appropriate
Rig / Platform / Drill Site*
Well
Sheet completed by Date
SURFACE LOCATION planned / actual* Datum/Ellipsoid Projection !"# $%% &' ()*
Structure reference Description + Lat. $°,-%$. N / S* Easting / 0 ,$1Long. $$°%-. E / W* Northing 0 ,$%1$1
Well reference point Description + $ (+! 23*Lat. $°,-%. N / S* Easting / 0 ,$$Long. $$°%-%. E / W* Northing 0 ,$%1%Offset from structure ref. %- N / S* 1%- E / W*
Elevation (land rig) Elevation (offshore)Drill datum RT / KB* Drill datum RT / KB*Drill datum to well ref. pt. Drill datum to MSL 1-Well ref. pt. to MSL Drill datum to well ref. pt. $%-
TARGET #1 TARGET #2 TARGET #3Name Name NameEasting / 0 ,$$ Easting / 0 , EastingNorthing 0 ,,1 Northing 0 ,,$ NorthingDepth TVDss %%- Depth TVDss - Depth TVDssTolerance Tolerance Tolerance- " ,% 4 ,1 - 4! ,$ 4 ,,$ - 5 ,$ 4 ,, - +6 ,% 4 ,,
Survey reference True / Grid* North arrows (diag.)Grid convergence (T to G)Magnetic declination (T to M)Magnetic model 77' Correction (magnetic to survey ref.)Correction (true to survey ref.)
,1° E / W*° E / W*
Date 8
,°,1°
Curved conductorsDrill datum to well reference point
MD TVD North East$- $%- %1- N / S* - E / W*
GM
decl. = +0.11
conv. = +2.34
Incl. at w.r.p. 1° Azim at w.r.p. %$$°
BP AmocoBPA-D-004 Directional Survey Handbook
C-12 Data and Work Sheets September 1999 Issue 1
DIRECTIONAL DESIGN CHECK LIST
Rig / Platform / Drill Site Well
DateSheet completed by
Checked by
/ CommentWell ObjectivesDocument from BU sub-surface teamUpdates to well objectives
Well Location Memorandum
Planning FileWell Plan Data SheetSurvey Program Data SheetProposed well trajectoryBU sub-surface approval of trajectoryTarget analysis (1 per target)
Offset well data (surveys, completion diags. etc.)Initial clearance scan (global scan)Tolerable Collision Risk Worksheet(s)Minimum separation calculationsAnti-Collision Instruction Sheet
Magnetic interference prediction
Relief well contingency calculation
Dispensations from Recommended Practice
Wellsite DrawingsPlan view drawingsVertical section drawingsStructure (spider) plots
Travelling cylinder - global clearance scanTravelling cylinder - working drawing(s)Travelling cylinder - wellsite plots
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-13
DIRECTIONAL DESIGN CHECK LIST
Rig / Platform / Drill Site Well
DateSheet completed by
,
Checked by +9:
/ CommentWell ObjectivesDocument from BU sub-surface team 5 !! !#; <=; ,
Updates to well objectives !" != <= 9!:
Well Location Memorandum 5::!9;
Planning FileWell Plan Data Sheet
Survey Program Data Sheet
Proposed well trajectory 8":= %
BU sub-surface approval of trajectory <= 9!:
Target analysis (1 per target)
Offset well data (surveys, completion diags. etc.) 9:= 3:!"!9 !!3
Initial clearance scan (global scan)
Tolerable Collision Risk Worksheet(s)
Minimum separation calculations + +> ":=6
Anti-Collision Instruction Sheet
Magnetic interference prediction + +> ":=6
Relief well contingency calculation
Recommended Practice Dispensation Form(s) !" =):3= 8
Wellsite DrawingsPlan view drawings
Vertical section drawings ?
Structure (spider) plots "@6:"3
Travelling cylinder - global clearance scan
Travelling cylinder - working drawing(s)
Travelling cylinder - wellsite plots ?
BP
Am
ocoB
PA
-D-004
Directional S
urvey Handbook
C-14 D
ata and Work S
heetsS
eptember 1999 Issue 1
SURVEY PROGRAM DATA SHEET
Rig / Platform / Drill Site Well Program version Sheet completed by Date
Survey Tool / Error Model Hole Casing Depth interval Comments / ContingencySize Size from to
BP
Am
ocoD
irectional Survey H
andbookB
PA
-D-004
Septem
ber 1999 Issue 1D
ata and Work S
heets C-15
SURVEY PROGRAM DATA SHEET
Rig / Platform / Drill Site
Well
Program version
Sheet completed by
Date
Survey Tool / Error Model Hole Casing Depth interval Comments / ContingencySize Size from to
!" "# $ %&%' '
!" "# %$ ' ' "( () * "* !+, * ,
-. !! %$ ' '! "/ ), ", ()#" ! #," *
)) #+) / (
-. 0 1 !+ " ," $ ' '
2 "!! !#+ -()#" &$ %&%' '
-. 0 1 !+ " ," &$ ' '! "/ ), ", ()#" ! #," *
)) #+) / (
BP AmocoBPA-D-004 Directional Survey Handbook
C-16 Data and Work Sheets September 1999 Issue 1
ANTI-COLLISION INSTRUCTION SHEET
Rig / Platform / Drill Site Well
DateSheet completed by
BU authorisation
The instructions given in this sheet are based on: 999
Well plan no. Date Survey program no. Date
and are not otherwise valid.
Wells to be Shut InMinimum Shut-in Interval
Well name Slot MD from MD to Comment
Minor Risk WellsWell name TCR* Key Assumptions
*Tolerable Collision Risk
Travelling Cylinder PlotsPlot no. Depth from Depth to Date Comment
Contingency Plans / Special Instructions
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-17
ANTI-COLLISION INSTRUCTION SHEET
Rig / Platform / Drill Site Well
DateSheet completed by
BU authorisationA:9 2" ,
The instructions given in this sheet are based on:Well plan version no. Date
1
Survey program version no. Date1 ,
and are not otherwise valid.
Well Shut-insMinimum Shut-in Interval
Well name Slot no. MD from MD to Comment% $- - # ?! !6 :) . !:=
, $- ,- : !B
Minor Risk WellsWell name TCR* Key Assumptions
*Tolerable Collision Risk
Travelling Cylinder PlotsPlot no. Depth from Depth to Date Comment
$- ,1- 1
,1- 1
Contingency Plans / Special Instructions
5 ! 2= !==3 !B B ( * "9!:= )B:= ::= )" =:==
6:= 2 !#= 2C > "::= !9 = !38: ) :":=! ":" B: := . !:=
!"! (-* D B ! ,- ' :! "!6:= " !8:3!=
9!6" =!"C :":=! ":" 9!# ": !9 !B!" ) 9! "2!2::C ) ::=
BP AmocoBPA-D-004 Directional Survey Handbook
C-18 Data and Work Sheets September 1999 Issue 1
DISPENSATION FROM RECOMMENDED PRACTICE
To be used for recording planned violations of standard directional and survey procedures and recommended practices
Rig / Platform / Drill Site Well
DateSheet prepared by
Recommended Practice Document
Procedure / Standard to be violated
Details of Dispensation Requested
Justification
Attachments
Technical Assessment / Recommendation Signature / Date / Comment
BU Authorisation
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-19
DISPENSATION FROM RECOMMENDED PRACTICE
To be used for recording planned violations of standard directional and survey procedures and recommended practices
Rig / Platform / Drill Site Well
DateSheet prepared by
=3C +9:
Recommended Practice Document:"C 89= :":=! !: ) :=
Procedure / Standard to be violated!" !=!C: =):3= 8 (E*
Details of Dispensation Requested
":"- !" )" !" 2 !6!3 ! $E =):3=
Justification
"!:! 9:=:969 :F )" 3":"- !" !#= ! - !" )):8 := )"
62!=:!C "36:= ::= 6="!:=C " =!":= :! !" 363 =):3= 8
!"3 B: <= =
Attachments
* !" !=!C: ":=6 ! E; $E !=3 $E =):3=
* < = 9!:;
Technical Assessment / Recommendation Signature / Date / Comment
A =:3" :=):3 ")"=:= )" )66" B
!C"; >75; %
BU Authorisation
"83
=; :"C 5 &; $
BP AmocoBPA-D-004 Directional Survey Handbook
C-20 Data and Work Sheets September 1999 Issue 1
NON-COMPLIANCE / NON-CONFORMANCE REPORT
To be used for reporting unplanned violations of standard directional and survey proceduresor unplanned deviations from directional plan or survey program
Rig / Platform / Drill Site Well
DateSheet prepared by
Procedure / Standard / Plan / Program document
Procedure / Standard / Plan / Program violated
What happened
Most serious likely consequence
Contributory causes
Action Responsible Date
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-21
NON-COMPLIANCE / NON-CONFORMANCE REPORT
To be used for reporting unplanned violations of standard directional and survey proceduresor unplanned deviations from directional plan or survey program
Rig / Platform / Drill Site Well
DateSheet prepared by
=3C +9: % %
Procedure / Standard / Plan / Program document "::= ""!9 := % +6"8C:= ""!9
Procedure / Standard / Plan / Program violated 1. := '5G< +! "":= +6"8C
What happened'5 6"8C := 1. := B" = ""3 )" < ! := "!:9 :":=!
":" (7 "B=* 6 +> )B!" !:3 "":= !69!:!C '5 =:="
(+ 7"=* !3 = = 6"8C ""!9
Most serious likely consequence= : B; """ 63 !8 "@6:"3 ?"! 3:":=! B"# := $ . := = " :"C
B; B" $. C" : = "6=; !" 63 !8 2= 9:3 ::2 :="! :=
!=:::= ":#
Contributory causes:":=! ":" B! 6=)!9::!" B: +> )B!"; !=3 63 : B= '4 )B!" )"
6"8C !6!:=
'5 9!=C !3 = 2= 3 ) "@6:"9= )" ! "":=
Action Responsible Date
3 )" ! "":= 2 =3 = +6"8C ""!9 !!
+ B" !"":!
+9: H66" B
:":=! 9!=C !9=3 @6!:C "36" I
4=6" ! - "!:=3 = +> 3!! ="C
+=3 C ) +6"8C ""!9 !! + ! 6"8C
9!=C "!:= +6"8:" ":" 63
+9: %
BP AmocoBPA-D-004 Directional Survey Handbook
C-22 Data and Work Sheets September 1999 Issue 1
List all the consequencesof collision and the
necessary remedial action
STOPUse
Conventionalrule - Major
risk
Are theconsequences
of collisionpredictable
?
Do theconsequences
of collision include a riskto personnel or the
environment?
Estimate the totalcost of collision
Estimate the valueof the planned wellto the BU
Is there apractical way to
substantially reduce eitherthe probability of collision or
the severity of theconsequences
?
noyes
no
no
yes
yes
Prepared by:
Authorised by:
How could the probability of collision or theseverity of the consequences be reduced ?How might this impact the drilling operation ?
Accepting a finite risk of collision will reduce thevalue of the planned well. What reduction, as afraction of the total value, are you prepared totolerate ? (guideline = 0.05)
Tolerable Collision Risk =
Estimate the totalcost of substantiallyreducing the risk
Given the uncertainty in the above estimates, byhow many times must the savings made from notreducing the risk outweigh the risk itself ?(guideline = 20)
M =
Tolerable CollisionRisk Worksheet
= 1 in
=
> 1 : close approach tolerances need not be set
< 1 :Tolerable
Collision Risk = 1 in
Use this sheet to justify classifying a well as Minor risk and toestablish the Tolerable Collision Risk for use in risk-based
well separation rule.Ref. BPA-D-004 (Dir. Svy. H’book) Sections 4.2, 4.3
V =
C =
F =
VF
C
VF
C
VF
C
C
VFF
M= =1
V =
H.Williamson, UTG Well Integrity
Key Assumptions (Elements of the drilling program which are critical to the above analysis)
Scenario Name:
(Be specific. Include all factors which affect eitherthe cost of collision or the cost of reducing the risk)
Description:
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-23
List all the consequencesof collision and the
necessary remedial action
STOPUse
Conventionalrule - Major
risk
Are theconsequences
of collisionpredictable
?
Do theconsequences
of collision include a riskto personnel or the
environment?
Estimate the totalcost of collision
Estimate the valueof the planned wellto the BU
Is there apractical way to
substantially reduce eitherthe probability of collision or
the severity of theconsequences
?
noyes
no
no
yes
yes
Prepared by: Stuart Telfer (Directional Engineer)
Authorised by: Richard Harland (Ops Superintendant)
How could the probability of collision or theseverity of the consequences be reduced ?How might this impact the drilling operation ?
Accepting a finite risk of collision will reduce thevalue of the planned well. What reduction, as afraction of the total value, are you prepared totolerate ? (guideline = 0.05)
Tolerable Collision Risk =
Estimate the totalcost of substantiallyreducing the risk
Given the uncertainty in the above estimates, byhow many times must the savings made from notreducing the risk outweigh the risk itself ?(guideline = 20)
M =
Tolerable CollisionRisk Worksheet
= 1 in
=
> 1 : close approach tolerances need not be set
< 1 :Tolerable
Collision Risk = 1 in
V =
C =
F =
VF
C
VF
C
VF
C
C
VFF
M= =1
V =
H.Williamson, SPR Well Design
Marnock A01Y Parallel S/T in Reservoir
Sidetracking an existing well (A01Z) by paralleling it through the reservoir section. Original well is sidetracked below the 13 3/8” casing drilling 12 1/4” and 8 1/2” hole sections. The original well, under conventional rules is classed as MINOR risk as it is closedin and abandoned. Interference occurs in 8 1/2” hole from4060m to 4590m.
1. Estimated treatment due to contamination from original wellbore and potential mud loss £ 50k Mud loss is not expected, merely contamination through barite sag in the original hole requiring treatment to the sidetrack hole system.2. Potential well control due to reservoir fluid on the highside of the original wellbore £ 200k (est. 2 days rig time @ £100k/day)3. Plugback and sidetrack well (est. 6 days rig time @ £100k/day) £ 600k
Moving South edges of the drillers target Northby 10m at entry and 63m at TD would result in:
1. Increased directional control to achieve smaller targets, cost in extra rig time = 8 days
2. Increased risk of sticking by 25% through greater sliding requirement, potential impact of becoming stuck, 12 days rig time.
0.25 x 12 days = 3 days
Total = 11 extra days @ £100k/day
£ 1.10 m
20 0.05
0.065
15
850k
Use this sheet to justify classifying a well as Minor risk and toestablish the Tolerable Collision Risk for use in risk-based
well separation rule.Ref. BPA-D-004 (Dir. Svy. H’book) Sections 4.2, 4.3
Scenario Name:
(Be specific. Include all factors which affect eitherthe cost of collision or the cost of reducing the risk)
Description:
Key Assumptions (Elements of the drilling program which are critical to the above analysis)
BP AmocoBPA-D-004 Directional Survey Handbook
C-24 Data and Work Sheets September 1999 Issue 1
List all the consequencesof collision and the
necessary remedial action
STOPUse
Conventionalrule - Major
risk
Are theconsequences
of collisionpredictable
?
Do theconsequences
of collision include a riskto personnel or the
environment?
Estimate the totalcost of collision
Estimate the valueof the planned wellto the BU
Is there apractical way to
substantially reduce eitherthe probability of collision or
the severity of theconsequences
?
noyes
no
no
yes
yes
Prepared by: Larry Wolfson 12/6/96
Authorised by: Adrian Clark 15/6/96
How could the probability of collision or theseverity of the consequences be reduced ?How might this impact the drilling operation ?
Accepting a finite risk of collision will reduce thevalue of the planned well. What reduction, as afraction of the total value, are you prepared totolerate ? (guideline = 0.05)
Tolerable Collision Risk =
Estimate the totalcost of substantiallyreducing the risk
Given the uncertainty in the above estimates, byhow many times must the savings made from notreducing the risk outweigh the risk itself ?(guideline = 20)
M =
Tolerable CollisionRisk Worksheet
= 1 in
=
> 1 : close approach tolerances need not be set
< 1 :Tolerable
Collision Risk = 1 in
V =
C =
F =
VF
C
VF
C
VF
C
C
VFF
M= =1
V =
H.Williamson, SPR Well Design
Niakuk Segment 3/5 Development Wells
New development wells drilled to segment 3/5 locationsencountering interference with adjacent wells. Shallownudges and varying KOPs used to move the interferencedepth below the surface casing.
• Collision with a producer/injector results in a side-track of that well: $2-$2.5 million (based on P2-50B)• Plug back and side-track the drilling well: $200k - $500k• The cost of delayed production/injection from both wells is estimated at $60 per bopd. NK-10 is a significant injector that supports 12,000 bopd and the average production from the producers is 3,000 bopd. The cost of a collision includes delayed production for both wells: - Injector: $900k - Producer: $360k• Estimated total cost (range): $2.56 - $3.90 million.
0.103
10
$3.9 million
$8.0 million
0.05
Use this sheet to justify classifying a well as Minor risk and toestablish the Tolerable Collision Risk for use in risk-based
well separation rule.Ref. BPA-D-004 (Dir. Svy. H’book) Sections 4.2, 4.3
Scenario Name:
(Be specific. Include all factors which affect eitherthe cost of collision or the cost of reducing the risk)
Description:
Key Assumptions (Elements of the drilling program which are critical to the above analysis)
Surface casing set above start of zone of interference (6,600 ft MD)
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-25
List all the consequencesof collision and the
necessary remedial action
STOPUse
Conventionalrule - Major
risk
Are theconsequences
of collisionpredictable
?
Do theconsequences
of collision include a riskto personnel or the
environment?
Estimate the totalcost of collision
Estimate value ofthe planned wellto the BU
Is there apractical way to
substantially reduce eitherthe probability of collision or
the severity of theconsequences
?
noyes
no
no
yes
yes
Prepared by: James O’Connor
Authorised by: Liam Cousins (Ops Superintendant)
How could the probability of collision or theseverity of the consequences be reduced ?How might this impact the drilling operation ?
Accepting a finite risk of collision will reduce thevalue of the planned well. What reduction, as afraction of the total value, are you prepared totolerate ? (guideline = 0.05)
Tolerable Collision Risk =
Estimate the totalcost of substantiallyreducing the risk
Given the uncertainty in the above estimates, byhow many times must the savings made from notreducing the risk outweigh the risk itself ?(guideline = 20)
M == 1 in
=
> 1 : close approach tolerances need not be set
< 1 :Tolerable
Collision Risk = 1 in
V =
C =
F =
VF
C
VF
C
VF
C
C
VFF
M= =1
V =
H.Williamson, SPR Well Design
Mungo 22/20-A09(169)[W12]
Interference with previous exploration and development wellswhen achieving W12 target. Well plan must pass between thetwo wells to achieve W12 target. Both wells are suspended.The development well is awaiting abandonment. The section ofgreatest collision risk with the development well has highpercentage casing wear and is of no future use to the asset.
Collision with either well would provide a conduit for reservoir pressure to into the 12 1/4” section of the planned well. However as the reservoir pressure is c.1.3sg and drilling fluid is 1.65sg the risk of a well control incident is no greater than when Top Reservoir Target is reached in 12 1/4” section.Estimated costs:1. Plugback and sidetrack well (estimate 4 days rig time @ £140k/day) £ 560k2. Bit damage (estimate £50k) £ 50k
Programmed FIT achieved at 13 3/8” casing shoe (the drilling programme calls for revision of risks if the FITis not achieved).
Collision risk would be reduced if the wellpathaccessed the area via a much more tortuouspath.
•250mMD extra -> £150k
•increased risk of stuck pipe -> £150k
•increased risk of not setting casing -> £300k
£600k
200.05
0.049
20
610k
Tolerable CollisionRisk Worksheet
Use this sheet to justify classifying a well as Minor risk and toestablish the Tolerable Collision Risk for use in risk-based
well separation rule.Ref. BPA-D-004 (Dir. Svy. H’book) Sections 4.2, 4.3
Scenario Name:
(Be specific. Include all factors which affect eitherthe cost of collision or the cost of reducing the risk)
Description:
Key Assumptions (Elements of the drilling program which are critical to the above analysis)
BP AmocoBPA-D-004 Directional Survey Handbook
C-26 Data and Work Sheets September 1999 Issue 1
#
BP AmocoDirectional Survey Handbook BPA-D-004
September 1999 Issue 1 Data and Work Sheets C-27/28
DIRECTIONAL SURVEY HANDBOOK (BPA-D-004) - CHANGE REQUESTForward to the Directional & Survey Specialist, UTG Well Integrity Team
Request made by: Date:
Business Unit / Organisation:
Job Title:
Tel: E-mail:
Section Title: Page(s) affected:
Details of Change
UTG / ODL Action