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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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ergerPrivate
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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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ergerPrivate
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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
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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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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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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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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
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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
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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 )
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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
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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
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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)
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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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Simple
Unrestricted flow path
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
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Effective wiping
Durable steel, nitrile construction
350 oF Temperature rating
Unrestricted flow path
Predictable pressures
Pressure indication NOT sensitive totemperature or rheology
Reusable
Simple, low maintenance
0
PPT - Wiper Dart
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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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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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Second dart bump
Pressure increase
Cement Stinger
Divertor Sub
Locator Sub with
1st dart (sheared)
2nd Wiper Dart
PPT - Operation (3)
Mud
Cement
Spacer
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Pressure bled down
cement underbalanced
Locator Sub
with darts
PPT - Operation (4)
Mud
Cement
Spacer
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PPT - Operation (5)
Pull slowly
above cement
and circulate
Locator Sub
with darts
Mud
Cement
Spacer
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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
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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
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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
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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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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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Diverter Tool
8 holes phased at 450
Bull Plug
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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
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Bad Cement Placement Technique
9.0 lb/galMUD
9.0 lb/galMUD
SPACER
13.8lb/gal15.8 lb/gal17.5 lb/galCEMENT
BENTONITE PILL
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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?
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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
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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
Recommended