module ppt tool nov-99

8/12/2019 Module PPT Tool Nov-99

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ergerPrivate

Dowells Plug Placement Tool

A key element forsuccessful cement plugs


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2 Initials

Effective Cement Plug Placement

Methods for Improving Cement Plug Placement

Cement Plug Usage

Reasons for cement Plug Failure

Design Consideration

Placement Technique

Successful Horizontal Placement

PPT Tool

Conclusions


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3 Initials

Cement Plug Usage Abandonment

Suspension

Kick-off

Lost circulation

U.K. Sector North Sea Cementing

0

1020

30

40

50

Primary Remedial Cement

Plug

Grouting

Side track

Casing shoe repair

Perforation isolation


4/31

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4 Initials

Cement Plug Failure Effects

Surface water contamination

Interzonal Communication

Customer Distribution of Lost Time

010203040

506070

CasingJobs

CementPlugs

% of Jobs % of Lost Time

% of

Total

Cement sheath in drillpipe

future operation failures

Lost Time - $


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5 Initials

Effect of Mud Contamination

Mud Contamination (% by Volume)Comp.

Strength

(PSI)

0

1000

2000

30004000

5000

6000

0 10 20 30 40 50

8 Hour 16 Hour

Reasons for plug failures

Drilling out too soon WOC as designed

Inaccurate well data BHST, caliper

Insufficient volume

% excess, execution, losses

Sinking of plug

off-bottom placement

Poor mud removal

Contamination in-outstring


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6 Initials

Design Considerations

Plug length, depth,volume

Spacer type

pseudo oilbased mud

weighted spacer

washes

quantity

Slurry design density (differential)

CemCRETE

compressive strength CemCRETE

rheology stability free water

fluid loss

All slurry properties including strength development

to be measured at BHCTand never at BHST


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7 Initials

Mud Removal

Pre-job circulation

minimum bottomsup

Hole cleaning Temperature

low PV, YP,Homogeneity

Pipe centralisation

if not done, must becompensated for

Can it beachieved???

Pipe movement

rotation (20-40 rpm)

Displacement rate

turbulent flow

effective laminar flow


8/31

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8 Initials

Mud/Cement Interface Stability

Idealised case Experimental results

unstable interface

9.0 PPG Mud

Spacer

17 ppg Cement

9.0 PPG Mud

Bentonite Pill

Off Bottom Placement


9/31

SchlumbergerPrivate

9 Initials

Off Bottom Placement

Suitable anchorplaced prior to cement

hi-vis mud pill

reactive mud pill

steel bridge plug

PROTECTOZONE*

ZONELOCK* Divertor sub at end

* Mark of Schlumberger

Blanked Mule Shoe

2 7/8" or 3 1/2" Tubing Joint

1" x 6" Cut Slots

+/- 6 Ft( 90 Phasing )


10/31

SchlumbergerPrivate

10 Initials

Placement Technique

Multiple drillpipe sizes to beavoided.

Tubing stinger for all plugs

3 1/2-in. O.D. preferred (mostcases)

1.5 times cement plug length

Divertor sub must be used

Correct underdisplacement

depends on stinger/pluglength

and on drill pipe/stinger

capacities

Correct displacementrate

Raise Pipe out of Plug

Extremely slowly

Use of a drillpipe wiper

system

pipe cleaning

very precise control ofvolumes


11/31

SchlumbergerPrivate

11 Initials

Horizontal Placement

The most difficult cement job todesign and execute successfully

9 5/8Casing

Hole Angle = 87

13 3/8Casing

20 Casing

Slurry design BHCT prediction

Spacer design

Spacer volume

Anchor design Hole preparation

Mud removal

Execution

Pipe cleaning

Displacement

WOC


12/31

SchlumbergerPrivate

12 Initials

BHCT Prediction

TD = 9100 Ft

13 3/8 Casing

20 Casing

9 5/8 Casing

T.O.C. = 8600 Ft

9 5/8 Casing

Hole Angle = 87o

13 3/8 Casing

20 Casing

Horizontal Well

Vertical Well

API BHCT

Time (Hr)

140

150

160

170

180

190

200

210

0 5 10 15 20 25

Pre job

CirculationW.O.C.Cement Job

BHC

T(oF)


13/31

SchlumbergerPrivate

13 Initials

6 1/2-in. LOCATOR SUB 5-in. WIPER DART

PPT - Plug Placement Tool

Features

Effective drill pipe wiping

Durable steel, nitrile dart construction

350 oF Temperature rating

Unrestricted flow path

Multiple plug setting in one trip

Simple, low maintenance

Benefits

positive indication of displacement Precise volume control

Separation of fluids during injection downhole

Cleans drillpipe for future operations

Consistent and accurate cement plug setting


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SchlumbergerPrivate

14 Initials

Simple


High torque rating

High yield rating

High pressure rating

Low maintenance

Multiple usage

Easy to handle NC50 connection

4 3/4-in. tool available

Made in U.K.

6.5

52

3.00

2.50

PPT - Locator Sub


15/31

SchlumbergerPrivate

15 Initials

Effective wiping

Durable steel, nitrile construction

350 oF Temperature rating


Predictable pressures

Pressure indication NOT sensitive totemperature or rheology

Reusable

Simple, low maintenance

0

PPT - Wiper Dart


16/31

SchlumbergerPrivate

16 Initials

PPT - Operation (1)

All fluids in pipe and

circulating downhole

Mud

Cement

Spacer

1st Wiper Dart

Locator Sub

Cement Stinger

Divertor Sub


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SchlumbergerPrivate

17 Initials

First dart in place

Placement continuesLocator Sub with

1st dart (sheared)

2nd Wiper Dart

Cement Stinger

Divertor Sub

PPT - Operation (2)

Mud

Cement

Spacer


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SchlumbergerPrivate

18 Initials

Second dart bump

Pressure increase

Cement Stinger

Divertor Sub

Locator Sub with

1st dart (sheared)

2nd Wiper Dart

PPT - Operation (3)

Mud

Cement

Spacer


19/31

SchlumbergerPrivate

19 Initials

Pressure bled down

cement underbalanced

Locator Sub

with darts

PPT - Operation (4)

Mud

Cement

Spacer


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SchlumbergerPrivate

20 Initials

PPT - Operation (5)

Pull slowly

above cement

and circulate

Locator Sub

with darts

Mud

Cement

Spacer


21/31

SchlumbergerPrivate

21 Initials

Stab-in Cementing Benefits of wiper dart: (pipe stabbed-in or not)

Clean drillpipe after cementing

Indication of displacement

Reduce drillout time

Wiper Dart Launched,Displacement Underway

Plug bump. Pressure to 500 psi overCirc. Pressure. Bleed off to check float

Pull out of float collar/shoe andpressurize to 1500 psi to shear disc


22/31

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22 Initials

Dart Launch Methods

Semi Top Drive dart launcher

TOP DRIVE CONNECTION

LINE FROM

CEMENT UNIT

DART PIN

PULLER

DART TELL TALE

Top Drive dart launcherTOP DRIVE CONNECTION

LINE FROMCEMENT UNIT

TOP DART

BOTTOM DART REMOTE CONTROLLED

HYDRAULIC ACTUATORS


23/31

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23 Initials

Conclusions

Effects of failure can be more than lost time

Cement plugs require as much or more designconsiderations than casing cementation

All aspects of fluids, tubulars, and wellboreparameters must be considered to ensureeffectiveness

Setting of plugs in deviated hole sections can beeffectively achieved

PPT for every cement plug below 6,000 feet orin deviated hole sections greater than 30


24/31

Schlumbe

rgerPrivate

24 Initials

Two Plug Method

1. Running In 4. Top Plug Landed2. Bottom Plug Landed 5. Reverse Circulation3. Cleaning of Aluminium Tail Pipe and Pulling Out


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rgerPrivate

25 Initials

Two-Plug Method: Tell-Tale Catcher Sub

System

Advantages of this method are:

Isolation ahead and behind the cement.

Pipe cleaned down to the lower end of the tailpipe.

Breakable tail pipe that can be abandoned ifstuck.


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26 Initials

Diverter Tool

8 holes phased at 450

Bull Plug


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Schlumbe

rgerPrivate

27 Initials

Drill Pipe Centralization & Diverter Tool

DRILLPIPECENTRALIZED

9.0 lb/gal MUD

SPACER

9.0 lb/gal MUD

SPACER

16.0 lb/galCEMENT

DIVERTER TOOL

9.1 lb/gal VISCOUSBENTONITE PILL


28/31

Schlumbe

rgerPrivate

28 Initials

Bad Cement Placement Technique

9.0 lb/galMUD

9.0 lb/galMUD

SPACER

13.8lb/gal15.8 lb/gal17.5 lb/galCEMENT

BENTONITE PILL


29/31

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29 Initials

Job Design Considerations Why is the cement plug being set?

At what depth will the plug be set?

Across which formations is the plug going to be set?

At what density should the slurry be mixed?

What is the BHT?

What volume should be pumped?

What is the required thickening time?

How to insure the cement will not be contaminated by the mud? Are pipe centralization and rotation necessary?

Waiting on cement time?


30/31

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30 Initials

Slurry Properties Density - lighter for Lost Circulation

Density - heavier for Sidetracking

Density - homogeneous - batch mixing

Rheology - higher for Lost Circulation

Rheology - lower for placement with Coiled Tubing Compressive Strength - higher for Sidetracking

Compressive Strength - less important for Lost Circulation

Compressvie Strength - minimum 500 psi for drill out

Thickening Time - enough for placement - 1.5 to 2 hours


31/31

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31 Initials

Mud Contamination vs Compressive

Strength

* Compressive strength is 18hr at 230F** Contains dispersant

Neat Class H Cement16.5 lb/gal

Effect of MudContamination*

Mud Contamination(% by Volume)

Compressive Strength

(psi at 170F)Mud

Contamination(%)

NormalSlurry

15.6 lb/gal

ReducedWater

Slurry**17.5 lb/gal

05102050

4,6473,5122,6192,378

245

5,8625,3004,5382,331

471

0104060

4,082 psi2,950 psi2,426 psi

593 psi

8,600 psi8,237 psi3,850 psi2,967 psi

8 hr 16 hr

module ppt tool nov-99

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