an introduction to directional drilling

Directional Drilling presentation ١

An Introduction toAn Introduction to Directional DrillingDirectional Drilling (Advanced Drilling Engineering course)(Advanced Drilling Engineering course)

Instructor: Dr. Tabatabaei nejadLecturer: Mojtaba Owrangi -

87333102

Master of Petroleum Drilling & Production engineeringSahand University of Technology

In the name of Allah

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IntroductionIntroduction

1.1.

Definition & Reasons for D.DDefinition & Reasons for D.D2.2.

Reference Systems and CoordinatesReference Systems and Coordinates

3.3.

Types of Directional well trajectoriesTypes of Directional well trajectories4.4.

Calculation of a well trajectoryCalculation of a well trajectory

5.5.

Directional Drilling MeasurementsDirectional Drilling Measurements6.6.

Deflection ToolsDeflection Tools

7.7.

Principles of BHAPrinciples of BHA

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Definition & Reasons for DDefinition & Reasons for D..DD

DefinitionDefinition :The science of directing a well bore along a predetermined trajectory to intersect a designated subsurface target.

Kick off point (KOP):Kick off point (KOP):The kick off point is defined as the point below surface location where the well is deflected from the vertical.

TargetTarget:A predetermined point in the reservoir that D.D should reaches to it.

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Well classificationWell classificationVertical Well Wells with less than 10º

deviation

High Inclination Well

Wells between 60 and 85º

deviation

Horizontal Well Wells with more than 85º

deviation

Extended Reach Well

Horizontal/TVD displacement greater than 2.5

Designer Well Wells with significant turn in the horizontal plane of 30 to 180 degrees, and turn not restricted by inclination

Directional Drilling presentation ٦

Directional wellsDirectional wells

Radius Classification

Build Rate( degrees/30 meter )

Radius(meter)

Long Radius 1 -

6 1719 –

286

Medium Radius

7 –

30 285 –

57

Intermediate Radius

30 -

70 56 –

24

Short Radius 71 -

150 23 -

11.5

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Reasons for D.DReasons for D.D

1.

Side-tracking existing well (because of hole problems or fish or reaching new targets)

2.

Restricted surface locations (inaccessible locations)3.

To reach multiple targets4.

To reduce number of offshore platforms5.

Horizontal Drilling6.

To reach thin reservoirs (using horizontal wells)7.

Salt dome drilling (directing the well from the salt dome to avoid casing collapse problems)

8.

To avoid gas or water coning9.

For intersecting fractures10.

Relief wells11.

For controlling vertical wells12.

Shoreline drilling

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D.D applicationsD.D applications

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D.D applications (multiple targets)D.D applications (multiple targets)

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D.D applications (relief well)D.D applications (relief well)

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D.D applications (sideD.D applications (side--tracking)tracking)

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D.D applications (inaccessible locations)D.D applications (inaccessible locations)

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D.D applications (shoreline drilling)D.D applications (shoreline drilling)

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D.D applications (salt dome drilling)D.D applications (salt dome drilling)

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D.D applications (fault drilling)D.D applications (fault drilling)

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D.D applications (horizontal well) D.D applications (horizontal well)

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Horizontal wellHorizontal well

Horizontal wellsThe Incl. reaches to 90° through reservoir section

: بيشترين كاربرد در افزايش بهره برداري و در مخازن خاص مثل Fracture Limestone & Low permeability zone

Horizontal drain holes:BHA فوتي 30 خاص براي ايجاد زاويه خيلي سريع و در يك شعاع

2° per ftDeep Kickoff and Build: شبيه نوع

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Drilling Fluid SelectionDrilling Fluid Selection

Virtually all of the considerations for choosing a fluid for drilling a vertical hole apply to choosing a fluid for a directional hole:

Formation protectionHole cleaningLubricityInhibitionFluid weight requiredEconomicsEnvironmental impact

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Depth referencesMeasured Depth (MD)

Pipe tally, wire line depth counter, or mud loggers depth counter

True Vertical Depth (TVD)calculated from the deviation survey data

Inclination referencesis the angle (in degrees) between the vertical and the well boreaxis at a particular point.

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TVD & MDTVD & MD

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Azimuth referencesMagnetic North (measured by MWD)True (Geographic) NorthGrid North

Horizontal departure or displacement•

Horizontal distance between rig location & the target.

Note:

)( ndeclinationorthmagneticnorthTrue ±=

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Types of Directional well trajectories Types of Directional well trajectories

1.

Build and hold2.

Build-hole-drop (S type)

3.

Build-hold-drop-hold (modified S type)4.

Continuous build

5.

Deep Kickoff and Build

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Types of Directional well trajectories Types of Directional well trajectories

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Build and holdBuild and hold

Features:

Shallow kick-off point (KOP)Build-up sectionTangent section

Penetrate target at an angle equal to the Max buildup angleNo major changes in incl. & azimuth After build up sectionIncl: 15 – 55 deg or may be more

Applications:

Deep wells with large horizontal displacementsModerately deep wells with moderate horizontal displacement, where intermediate casing is not required

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BuildBuild--holehole--drop (S type) & Builddrop (S type) & Build--holdhold--dropdrop--hold (modified S type)hold (modified S type)

S type Modified S type

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BuildBuild--holehole--drop (S type) & Builddrop (S type) & Build--holdhold--dropdrop--hold (modified S type)hold (modified S type)

Features:Shallow KOPBuild-up sectionTangent sectionDrop-off section

There are several variations:

Build, hold &drop back to vertical (illustrated above)Build, hold, drop & hold (illustrated above)Build, hold & continuous drop through reservoir

Applications:

Multiple pay zonesReduces final angle in reservoirLease or target limitationsWell spacing requirementsDeep wells with small horizontal displacements

Disadvantages:

Increased torque & dragRisk of key seatingLogging problems due to inclination

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Continuous buildContinuous build

Features:Decrease in torque & dragLowest risk of key seatingContinuous build rate

Applications:This type occurs when using down-hole motors with bent sub.

KOP

Build Section

Target

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Deep Kickoff and BuildDeep Kickoff and Build

Features:Deep KOPBuild-up sectionShort tangent section (optional)

Applications:Salt dome drillingSidetrackingAppraisal wells to assess the extent of a newly discovered reservoir

Disadvantages:Formations are harder so the initial deflection may be more difficult to achieveHarder to achieve desired tool face orientation with down hole motor deflection assemblies (more reactive torque)Longer trip time for any BHA changes requiredBuild up rate is more difficult to control

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Calculation of a well trajectory Calculation of a well trajectory (build(build--hold where hold where XX33

< r< r11

))

Radius of curvature:

q= build rate (deg/100 ft)

Maximum inclination angle, ɵ, whenX3<r1 :

The length of arc, section DC:Or

Horizontal departure at the end of build section:

qr 1180

1 ×=π

⎟⎟⎠

⎞⎜⎜⎝

⎛−−

−⎥⎥⎦

⎤

⎢⎢⎣

⎡

−+−=

13

312

132

31

1 tan)()(

sinDD

XrarcDDXr

rarcθ

θπ××= 1180

rLDC qDCL θ=

)cos1(12 θ−= rX

Directional Drilling presentation ٣٣


< r< r11

))

The total measured depth:

TVD at the end of build section:

Measured depth at CP section:

Another way of expressing maximum inclination angle, in term of r1, D1, D3and X3 for X3<r1 is:

Ω++= tan11r

qM DD θ

θsin112 ⋅+= rDD

θcosPCCP′

= )sin( 11 θ⋅−−′=′ rDDPC

( )⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎥⎦

⎤⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛−−

×

−−−

=

−31

13

31

13

tansincos

)tan(

13

1

XrDDarcarc

XrDDarc

DDr

θ

Directional Drilling presentation ٣٤


> r> r11

))

The maximum inclination angle, ɵ can be calculated by:

⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎥⎦

⎤⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛−−

×⎟⎟⎠

⎞⎜⎜⎝

⎛−

−⎟⎟⎠

⎞⎜⎜⎝

⎛−−

−=

13

13

13

1

13

13

tansincos

tan180

rXDDarc

DDrarc

rXDDarcθ

Directional Drilling presentation ٣٥

Calculation of a well trajectoryCalculation of a well trajectory (S type)(S type)

r1

<X3

& r1

+r2

<X4 r1

<X3

& r1

+r2

>X4

⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎥⎦

⎤⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛+−

−×⎟⎟⎠

⎞⎜⎜⎝

⎛−+

−⎟⎟⎠

⎞⎜⎜⎝

⎛−−

−−=

)(tansincos

)(tan180

214

14

14

21

214

14

rrXDDarc

DDrrarc

rrXDDarcθ

( )⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎥⎦

⎤⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛−+−

×

−−+−

=

−+

421

14

421

14

tansincos

)tan(

14

21

XrrDDarcarc

XrrDDarc

DDrr

θ

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Example 1Example 1--

Design of D.D Design of D.D

Design a directional well with the following restrictions:

Total horizontal departure= 4500 ftTrue vertical depth (TVD)= 12500 ftDepth of KOP= 2500 ftRate of build of inclination angle= 1.5 deg/100ftType 1 well (build-hold)

A.

Determine the maximum hole angle?B.

What is the total measured depth?

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Design of D.D Design of D.D

Ans.r1=(180/Л)*(1/q)=(180/Л)*(100/1.5)= 3820 ft3820 ft

Because r1<X3:

ɵɵ=26.29 deg=26.29 deg

D1=2500 ft , D3=12500 ft , X3=4500 ft, r1=3820 ft Total measured depth:

DDMM =2500+1753+9264=13517=2500+1753+9264=13517 ftft

⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

⎥⎦

⎤⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛−−

×⎟⎟⎠

⎞⎜⎜⎝

⎛−

−⎟⎟⎠

⎞⎜⎜⎝

⎛−−

−=

14

14

14

1

14

14

tansincos

tan180

rXDDarc

DDrarc

rXDDarcθ

⇒

Ω++= tan11r

qM DD θ

Directional Drilling presentation ٣٨

Survey Calculation MethodsSurvey Calculation Methods

••

Various procedures have been developed to Various procedures have been developed to estimate the well bore trajectory as it is being estimate the well bore trajectory as it is being drilled. Eighteen methods are known for drilled. Eighteen methods are known for computing surveys, but the 3 most widely used computing surveys, but the 3 most widely used methods are the methods are the tangentialtangential, , angelangel--averagingaveraging and and minimum curvatureminimum curvature methods. methods.

••

The normal method for determining the well path The normal method for determining the well path is to ascertain the coordinates by using some is to ascertain the coordinates by using some type of surveying instrument to measure the type of surveying instrument to measure the inclinationinclination and and directiondirection at various depths at various depths (stations) and then to calculate the trajectory.(stations) and then to calculate the trajectory.

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Below is a list of the most used methods:1.

Acceleration method2.

Average angle method3.

Angle-averaging method4.

Backward station method5.

Balanced tangential method6.

Circular arc method7.

Compensated acceleration method8.

Mercury method9.

Minimum curvature method10.

Quadrant method11.

Radius of curvature method12.

Secant method13.

Tangential method14.

Terminal angle method15.

Trapezoidal method16.

Vector averaging method

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TangentialTangential methodmethod: (Backward station method) or (Terminal angle method)

the tangential method uses only the inclination and direction angles at lower end of the course length.It is inaccurate among other methods:

Li= latitude north/southMi= latitude east/westDi=

TVD segment

αi= inclination angleDMi= course length

εi= direction angle

⎪⎪⎪

⎩

⎪⎪⎪

⎨

⎧

=

=

=

⇒⎪⎭

⎪⎬

⎫

===

∑

∑

∑

=

=

=

n

iin

n

iin

n

iin

iMii

iiMii

iiMii

DD

MM

LL

DDDM

DL

1

1

1

)cos(.)sin().sin(.)cos().sin(.

αεαεα

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tangential methodtangential method

Use the following survey data to determine the trajectory coordinates for tangential method?

Measured depth, ft

Hole angle, deg

Azimuth3000

2

N 28 E

3300

4

N 10 E3600

8

N 35 E

3900

12

N 25 E5000

15

N 30 E

6000

16

N 28 E7000

17

N 50 E

8000

17

N 20 E9000

17

N 30 E

10000

17

N 25 E

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Average angle Or Angle Averaging Method:Average angle Or Angle Averaging Method:••

the angle averaging method is the simple average of the the angle averaging method is the simple average of the angles at the angles at the toptop

and and bottombottom

of course length. of course length.

⎪⎪⎪

⎩

⎪⎪⎪

⎨

⎧

=

=

=

⇒

⎪⎪⎪

⎭

⎪⎪⎪

⎬

⎫

+=

++=

++=

∑

∑

∑

=

=

=

−

−−

−−

n

iin

n

iin

n

iin

iiMii

iiiiMii

iiiiMii

DD

MM

LL

DD

DM

DL

1

1

1

1

11

11

)2

cos(.

)2

sin().2

sin(.

)2

cos().2

sin(.

αα

εεαα

εεαα

Directional Drilling presentation ٤٤


Average angle method Average angle method

Determine the trajectory coordinates for the corrected survey points given below:

Measured depth (ft)

inclination angle (deg)

direction angle7100

0

0

7200

10.1

S68W7300

13.4

S65W

7400

16.3

S57W7500

19.6

S61W

Note:For the first point the direction should not be averaged, it means that at MD= 7200 we use dir. = 248 instead of 124.MD= 7200 we use dir. = 248 instead of 124.For the first point the inclination should be averaged, so for MD=7200 the incl. = 5.05. MD=7200 the incl. = 5.05.

Directional Drilling presentation ٤٥


Minimum curvature methodMinimum curvature methodandand

Radius of curvature method:Radius of curvature method:

The minimum curvature methodThe minimum curvature methoduses the angles at A1 and A2 uses the angles at A1 and A2

and assumes a and assumes a curved well borecurved well boreover the course length over the course length

not a straight line.not a straight line.

Directional Drilling presentation ٤٦

is in [radian] and if it is less than 0.25 radian, it is reasonable to set F=1.0


( ) ( )( ){ }

( )( )

( )( )

( )

⎪⎪⎪

⎩

⎪⎪⎪

⎨

⎧

=

=

=

⇒

⎪⎪⎪⎪⎪⎪

⎭

⎪⎪⎪⎪⎪⎪

⎬

⎫

+⎟⎠⎞⎜

⎝⎛=

+⎟⎠⎞⎜

⎝⎛=

+⎟⎠⎞⎜

⎝⎛=

⎟⎠⎞⎜

⎝⎛⎟

⎠⎞⎜

⎝⎛=

−−−−=

∑

∑

∑

=

=

=

−

−−

−−

−−−

n

iin

n

iin

n

iin

iiiMi

i

iiiiiMi

i

iiiiiMi

i

i

i

iiiiiii

DD

MM

LL

FDD

FDL

FDM

F

1

1

1

1

11

11

111

.cos)cos(.2

.cos.sincos).sin(.2

.sin.sinsin).sin(.2

2tan.2

cos1sin.sincoscos

αα

εαεα

εαεα

ββ

εεααααβ

β

Directional Drilling presentation ٤٧

Comparison of accuracy of various calculation methodsComparison of accuracy of various calculation methods

North displacement & differences from actual (ft)

Total vertical depth & differences from actual (ft)

Calculation Calculation methodmethod

+43.09998.02-25.381628.61TangentialTangential

-0.21954.72-0.381653.61Balanced tanBalanced tan

+0.11955.04+0.191654.18AngleAngle--aveave..

0.0954.930.01653.99Radius of Radius of curvaturecurvature

0.0954.930.01653.99Minimum Minimum curvaturecurvature

0.04954.89-0.371653.63MercuryMercury

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Dogleg SeverityDogleg Severity

Large angle changes occurring over a short course length can Large angle changes occurring over a short course length can place high bending stresses on the pipe. In addition, these place high bending stresses on the pipe. In addition, these doglegs can cause key seating problems. Most operators place doglegs can cause key seating problems. Most operators place a limit on the amount of angle change allowable over a 100a limit on the amount of angle change allowable over a 100--ft ft segment. The limit is segment. The limit is 44--6 deg6 deg per 100 ft. per 100 ft.

DL: dogleg, deg/100ftDL: dogleg, deg/100ftL: course lengthL: course lengthII11, I, I22 : Inclination at upper & lower survey, deg: Inclination at upper & lower survey, degAA11, A, A22 : direction at upper & lower survey, deg: direction at upper & lower survey, deg

( )( )[ ]21212121 coscoscoscossinsinsinsin100

IIAAAAIILDL

++=

Directional Drilling presentation ٥٠

Directional Drilling MeasurementsDirectional Drilling Measurements

Magnetic single shot instrumentsMagnetic single shot instrumentsMagnetic multi shot instrumentsMagnetic multi shot instrumentsMeasurement while drilling (MWD)Measurement while drilling (MWD)

ElectromagneticElectromagneticAcousticAcousticPressure pulsePressure pulsePressure pulse modulationPressure pulse modulationCable & DPCable & DP

Directional Drilling presentation ٥١


Directional Sensor Hardware Directional Sensor Hardware The figure above shows the basic configuration of the DirectiThe figure above shows the basic configuration of the Directional Sensor onal Sensor

probe. The directional probe is mounted to the MWD assembly anprobe. The directional probe is mounted to the MWD assembly and d keyed into a Nonkeyed into a Non--Magnetic Drill Collar. The nominal length of the sub is Magnetic Drill Collar. The nominal length of the sub is 30 feet. The nonmagnetic collar is usually referred to as Monel.30 feet. The nonmagnetic collar is usually referred to as Monel.

Directional Drilling presentation ٥٢


Records– inclination– direction– tool face position

on sensitized paper or photographic filmInclination may be determined by

– a float on a liquid– a pendulum

Directional Drilling presentation ٥٣

Directional Drilling Measurements (Single shot)Directional Drilling Measurements (Single shot)

Procedure:– load film into

instrument– activate timer

(activate stopwatch)

–make up the tool– drop the tool– retrieve tool (wire

line or drill pipe)

Directional Drilling presentation ٥٤

Magnetic Multi shot InstrumentsMagnetic Multi shot Instruments

Are capable of taking numerous survey records in one run.

May be dropped down the drill pipe or run on wire line in open hole.The unit contains a watch that is spring wound and uses the power of the spring to operate a timer cam.The multishot tool is usually dropped down the drill pipe and landed in the nonmagnetic drill collar.

During the trip out, a survey is taken every 90 ft, i.e. every stand.More closely spaced stations could be obtained by stopping the pipe more often, and waiting for a picture.A stopwatch at the surface is synchronized with the instrument watch.

Directional Drilling presentation ٥٥

Magnetic Multi shot InstrumentsMagnetic Multi shot Instruments

Directional Drilling presentation ٥٦

MWD MWD ((Measurement While DrillingMeasurement While Drilling))

While drilling it is possible to transmit to the surface down hoWhile drilling it is possible to transmit to the surface down hole le information on:information on:

Inclination

temperatureDirection

weight on bit

tool-face

angle torque on bitgamma ray

sonic velocity

Resistivity

Inclination, direction, and toolInclination, direction, and tool--face angle are of particular face angle are of particular interest in directional drilling. A lower cost MWD tool can interest in directional drilling. A lower cost MWD tool can be used if only directional drilling information is required.be used if only directional drilling information is required.

Information is typically transmitted through the mud column by: Information is typically transmitted through the mud column by: ++veve

or or --

veve

pressure pulses, or pressure pulse modulationpressure pulses, or pressure pulse modulation

Directional Drilling presentation ٥٧

Deflection ToolsDeflection Tools

Hole angles are usually kicked off by jetting, whip stocks or some type of bent sub, down hole motor tools.

Geology affects the decision as well as the desire to use a steering tool.

1.

Jetting: It was a widely used technique several years ago. It involved the use of a large bit jet

and two smaller jets. After washing 6-8 ft rotary was used to drill the rest of the joint

2.

Whip stockis a very simple device used to kick off the well.Separated into 2 categories:

i.

Open hole whip stocksii.

Casing whip stocks

3.

Bent subs: are used with down hole motors. The sub has 1/2 -5/2 degree of bend in it that will

deflect the motor in the desired direction.

Directional Drilling presentation ٥٨

Deflection tools (Jetting)Deflection tools (Jetting)

JettingA standard soft formation tri-cone bit, with one very large nozzle and two smaller ones.

Important parameter:Geology:

S.S & oolitic limestone (best)Unconsolidated S.S & very soft rock (good)Very soft rocks erode too much (bad)

As a rough rule of thumb, ROP>24m/hr using normal drilling parameters

Hydraulic energyA rule of thumb: mud velocity through the large jet should be at least 500 ft/sec.

Directional Drilling presentation ٥٩

Deflection tools (Jetting)Deflection tools (Jetting)

Directional Drilling presentation ٦٠

Advantages & Disadvantages Of Jetting Advantages & Disadvantages Of Jetting

AdvantagesAdvantagesSame BHA to change Same BHA to change trajectory & drilling aheadtrajectory & drilling aheadSimple and cheap method Simple and cheap method in soft formations.in soft formations.Dogleg severity can be Dogleg severity can be partly controlled from partly controlled from surface by varying the surface by varying the number of feet number of feet ““jettedjetted””each time.each time.The survey tool is not far The survey tool is not far behind the bit.behind the bit.Orientation of tool face is Orientation of tool face is fairly easyfairly easy

DisadvantagesDisadvantagesOnly works in soft Only works in soft formation and therefore at formation and therefore at shallow depths.shallow depths.high dogleg severities are high dogleg severities are often produced. Deviation often produced. Deviation is produced in a series of is produced in a series of sudden changes, rather sudden changes, rather than a smooth continuous than a smooth continuous change. For this reason, it change. For this reason, it is normal practice to jet is normal practice to jet an under gauge hole and an under gauge hole and then open it out to full then open it out to full gauge, which smoothes gauge, which smoothes off the worst of the off the worst of the doglegs.doglegs.

Directional Drilling presentation ٦١

Deflection tools (Whip stock)Deflection tools (Whip stock)

Some movies about D.D:1.

Movie 1 (bottom trip W.S)

2.

Movie 2 (section milling)3.

Movie 3 (section milling)

4.

Movie 4 (retrieving a W.S)5.

Movie 5 (cement type W.S)

6.

Movie 6 (Casing W.S)

Directional Drilling presentation ٦٢


Directional Drilling presentation ٦٣


Whip stocksStandard removable Whip stock

used to kick off wellsSidetracking

DisadvantageIf the whip stock is set on the fill, then whip stock rotate when drilling startsFill tend to wash away, causing the bit to slide down the side of the well bore and entire whip stock assembly to rotateCritical: when bit leaves the end of W. wedge, if the rock too soft & circulation too high, bit can lose curvature and continuestraightnumber of “trips” involved.whip stock produced a sudden, sharp deflection

AdvantagesIt is a fairly simple piece of equipment which requires relatively little maintenance and has no temperature limitations.

Directional Drilling presentation ٦٤


•

Circulating Whip stock–

the drilling mud initially flows through a passage to the bottom

of

the whip stock which permits more efficient cleaning of the bottom of the hole and ensures a clean seat for the tool.

–

It is most efficient for washing out bottom hole fills.

Permanent Casing Whip stockused where a “window” is to be cut in casing for a sidetrackadvantage

operation usually takes less time.disadvantage

gives a sharp doglegCasing window is too short. Numerous trips & long hours of rotation can wear or damage the casing, difficult to trip out the BHA through the casing window

Directional Drilling presentation ٦٥


Directional Drilling presentation ٦٦

Down hole motorsDown hole motors

Was developed in 1966, and 2 years later the PDM Was developed in 1966, and 2 years later the PDM began to be used in the USbegan to be used in the USPDM & turbine + Bent Sub + Bent Housing or PDM & turbine + Bent Sub + Bent Housing or eccentric stabilizerseccentric stabilizers

turbine motor (left) and positive displacement motor (right) designs.

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PDM s vs. TurbinesPDM s vs. Turbines

PDM:The directional driller can use pump pressure as a weight indicatorlonger bit life

because of the slower rotary speed.

Use a small bend at the U-joint housing

instead of

bent subTurbine:

operate at highertemperaturesDO NOT have a dump valve.

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Factors Affecting directional behavior of rotary assembliesFactors Affecting directional behavior of rotary assemblies

Gauge and placement of stabilizersDiameter and length of drill collarsWeight -on-bitRotary speedBit typeFormation anisotropy and dip angle of the bedding planesFormation hardnessFlow rateRate of penetration

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PDM accessoriesPDM accessories

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Turbine accessoriesTurbine accessories

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Principles of BHA (Fulcrum)Principles of BHA (Fulcrum)

The Fulcrum principle is used The Fulcrum principle is used to build angle (increase to build angle (increase borehole inclination)borehole inclination)Full gauge near bit stabilizer, followed by 40 to 120ft DC, before the first string stabilizer, or no string stabilizer

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Principles of BHA (Fulcrum)Principles of BHA (Fulcrum)

The rate of build will be INCREASED by the following:

•

Increasing the distance from the near-bit stabilizer to the first string stabilizer •

Increase in hole inclination

•

Reduction of drill collar diameter•

Increase in weight on bit

•

Reduction in rotary speed•

Reduction in flow rate

(in soft formations)

Directional Drilling presentation ٧٦

Principles of BHA (Stabilization)Principles of BHA (Stabilization)

The Stabilization (Packed Hole) Principle:The Stabilization (Packed Hole) Principle:

hold angle and

direction

three stabilizers in quick succession behind the bit separated by short, stiff drill collar sections, then the three stabilizers will resist going around a curve and force the bit to drill a reasonably

straight path

Directional Drilling presentation ٧٧

Principles of BHA (Stabilization)Principles of BHA (Stabilization)

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Principles of BHA (Pendulum)Principles of BHA (Pendulum)

Drop angleDrop angle

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References

“Applied drilling engineering” Adam T.bourgoyne, spe text book,vol 2.“Oil well drilling engineering” H. Rabia, univ. of newcastle,1985.“Advanced directional drilling” drilling services, computalog, Texas.“Drilling engineering” N.J Adams, pennwell books, Tulsa, Oklahoma.“Drilling engineering workbook” baker huges INTEQ,80270H rev. B, Dec 1995.“IADC Drilling manual”, e-book version(11),2000.“Well engineering & construction” Hussein Rabia, e-book version.“Introduction to directional drilling” schlumberger hand out, 1998“Directional drilling training manual”, schlumberger handbook, 1996

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AttachmentAttachment--

review of 6 calculation methodsreview of 6 calculation methods

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That was all I knew about D.DThanks for your attention

an introduction to directional drilling

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