Slim-Hole and Coiled-Tubing
Technology
Dr. William J. McDonald
Thomas E. Williams
PTTC Technology Seminar
Lafayette, LA
December 5, 2000
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Drilling Engineering Association
(DEA)
 Sponsors
Joint-Industry R&D Projects
 28
Members (Operating Companies)
 22
Associates (Service Co’s and Consultants)

Currently 113 projects
 Typical
 Most
project: 10-15 participants
successful DEA projects:
DEA-44 Horizontal Well Technology
DEA-67 Slim-Hole and Coiled-Tubing
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DEA-67
Slim-Hole and Coiled Tubing Technology
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Sponsors:
Texaco & BP
Start Date:
January 1, 1992
End Date:
December 31, 2000
Participants:
65
Tasks:
22
Budget:
$3 Million
3
DEA-67 Tasks
1. Update Software
2. New Software
3. User’s Group
4. New Technology
5. Drill-String Design
6. Motors and Bits
7. MWD and Geosteering
8. Well Control
9. UB Drilling/Completion
10. Logging Tools
11. Perforating Systems
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12. Completion Techniques
13. Stimulation Techniques
14. Production/Workovers
15. Through-Tubing
16. Field Tests
17. Case Histories
18. Well-Planning Manual
19. Composite Tubulars
20. Multibranch CT
21. Schools
22. Forums
4
DEA-67 Deliverables
Major
reports
Computer
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programs
6
9
Forums
6
Schools
8
5
Advances in
Slim-Hole Technology
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Summary
Slimholes:
-Reduce Well Costs 40 to 70%
-Reduce Environmental Costs & Concerns
-Tools and Equipment Exist, and are
Available and Reliable
-Safe
-Do Not Usually Limit Production
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Overview
Historical
Types
Background
of Slim-Holes
Slim-hole
Cost Savings
Evolution
and Experience
Concerns
and Conclusions
Outlook
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93
96
87
90
81
84
75
78
69
72
63
66
57
60
51
54
45
48
39
42
Number of Publications
Publications on Slim Hole
60
50
40
30
20
10
0
YEAR
9
Stekoll Slimhole
Pumping System (1960)
1” Tee
Rubber Hose
Clamp
Flow Line
Conventional
Stuffing Box
Gas Vent
Polished Rod Liner
2 7/8” Casing
1” EUE Pumping String
Blind Cage
Traveling Barrel Insert Pump
Screen
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Slip-Type Hold-Down
with Rubber Removed
10
Stekoll Field Well (1960)
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STEKOLL Field Experience (1960)
 Over
1,300 Wells: Kansas, Texas, Canada
 1,000
 1”
to 3,000 Foot Wells
EUE Tubing (Hollow Sucker Rod)
 2-1/2”
& 2-7/8” Inch Casing
 70
BOPD
 40
to 50% Reduction in Tubular Costs
 17%
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Overall Cost Savings
12
STEKOLL Slimhole
Operations (2-7/8”)
 Drilling
& Logging
 Perforating
 Acidizing
 Fishing
& Squeeze Cementing
& Fracturing
& Washovers
 Sand
Bailing
 Dual
Completions
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Hollow Sucker Rod Advantage
“The hollow sucker rod combines the
function of the sucker rod and the
tubing, so it is no longer necessary to
pull both sucker rods and tubing
when working over wells.”
STEKOLL, 1960
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STEKOLL System Limitations (1960)
 Limited
Slimhole Logging Tools
 Workover
 Tubing
Concerns
Failures
 Resistance
to Slimholes
 Resistance
to New Technology
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Continuous
Coring
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Rotary
Drilling
Mud Motor
Collar
Core Barrel
Slim-Hole Systems
Downhole
Motor
16
Amoco SHADS Rig
(Continuous Coring)
Drawworks
Sandline
Hydraulic drive
Wireline overshot for
core retrieval
Top drive (0-2250 rpm)
Slim annulus
(<1/2”)
Wellbore
Flush-joint
drill rod
4-3/8” core bit
(0-10,000 lb WOB)
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Slim-Hole Motor Drilling
in Wyoming
Amoco (1995)
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Microdrill Slim-Hole Rig
(Rotary Drilling)
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Slim-Hole Drilling Site
Slim-Hole Site
160 ft
(BP, 1994)
330 ft
200 ft
Conventional Site
Site Reduced by 75%
390 ft
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Material Cost Savings
(3” vs. 8”)
80
80%
70
70%
% Savings
60
50
40
40%
30
20
10
0
MUD
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CASING
CEMENT
23
MICRODRILL COSTS
(1500-5000 ft DEPTH)
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Slim-Hole Drilling and Completion
Cost Savings
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SLIM-HOLE RIG COSTS
(McLAUGHLIN, 1959)
1,000
DAILY COSTS ($)
800
800
5 MEN
625
600
525
4 MEN
4 MEN
400
335
3 MEN
200
0
9"
6 3/4"
5 5/8"
3 3/4"
HOLE SIZE
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SLIM-HOLE CASING AND TUBING COSTS
(McLAUGHLIN, 1959)
7" CASING
2 7/8" TUBING
RELATIVE COST
5 1/2" CASING
2 3/8" TUBING
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4" CASING
1 1/2" TUBING
2 3/8" CASING
NO TUBING
27
40% Savings For 5000-ft WELLS
(BONSALL, 1960)
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Savings For 5000-ft Wells (cont.)
SLIM HOLE
($)
CONVENTIONAL % OF TOTAL
($)
SAVINGS
ACID
150
600
3
LOGGING
850
850
--
PERFORATING
450
350
-1
FRACTURING
3300
4500
8
LOCATION EXPENSE
2500
2500
--
MUD
1000
1000
--
CORE ANALYSIS
200
200
--
37,470
52,220
100
TOTAL:
2209314X
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Cost Savings with Slim Holes
OPERATOR
LOCATION SAVINGS YEAR
Hudson's Bay
Canada
28%
1959
Western Mining
Australia
75%
1984
Oryx
Texas
50%
1991
Elf/Microdrill
Paris Basin
65%
1992
Maraven
Venezuela
20%
1994
Chevron
California
66%
1995
Wilcox Operators
Texas
15%
1995
GUPCO/Amoco Gulf of Suez
20%
1995
Shell
Madagascar
40%
1996
ARCO
Alaska
26%
1996
Remote Coring Operations
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SLIM-HOLE COSTS
6.0
(WESTERN MINING, 1984)
WELL COST ($ MM)
2000m TD
DRY HOLE
ONSHORE
4.0
CONVENTIONAL
2.0
0
LOCAL
SLIM HOLE
REMOTE
LOGISTICS
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Conoco Indonesia Slim-Hole Costs
(MACFADYEN et al., 1986)
1980-81
(CONV)
1983
(SH)
1985-86
(SH)
5
3
12
7,670,000
4,680,000
2,060,000
TOTAL FOOTAGE
18,962
11,740
29,179
AVERAGE DEPTH
3,792
3,913
2,432
2,770,000
960,000
760,000
NO. OF LIFTS
317
187
100
NO. OF DAYS
16
9
5
HELICOPTER
PUMA
PUMA
S-58T
NUMBER OF WELLS
AVERAGE WELL COST
DRILLING
DRILLING COST/WELL
LOGISTICS
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ORYX
HORIZONTAL SLIM-HOLE COSTS
(HALL AND RAMOS, 1992)
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1991-92 ORYX SLIM-HOLE RE-ENTRIES
(HALL AND RAMOS, 1992)
DAYS DEPARTURE LATERAL COST TOTAL COST
18
1458
3.88 (CT)
0.63
38
2018
3.31
0.74
24
2002
1.84
0.41
21
2692
1.46
0.43
20
2242
1.83
0.45
18
1927
2.36
0.50
14
1600
1.75
0.31
22
1900
2.60
0.54
AVG 22
1980
2.38
0.50
1991 CONVENTIONAL COST = 1.00
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ORYX'S CONCLUSION (1992)
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Domain Energy Slimholes (1995)
Cased Hole
Open Hole
7-7/8” Hole
1518’
5-1/2” Casing
9-7/8” Hole
1520’
4-3/4” Hole
7-5/8” Casing
4-3/4” Hole
Inflatable
Casing Packer
Cement
10697’
TD 10926’
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2-7/8”
TD 10909’
Production Casing
2-7/8”
Production Casing
36
Domain Energy Slim-Hole (1995)
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Location:
Green River Basin, WY
Rig Modification:
Bowen S3.5 Power Swivel
Hole Diameter:
4-3/4 inches
Casing Diameter:
2-7/8 inches
Drill Pipe Diameter:
2-7/8 inches
Collar Diameter:
3-1/2 inches - 3 stabilizers
Motor Diameter:
3-3/8 and 3-3/4 inches
Drilling Rate:
Up to 2x increase
Problems:
4 Twist-offs (stabilizer torque)
Successes:
Cementing/Logging/Perforating
Cost Savings:
Breakeven (due to twist-offs)
37
Domain Energy Slim-Hole Problems (1995)

Slim-Hole No. 1




Slim-Hole No. 2






Hole deviation (no stabilizers)
Low ROP (reduced WOB due to hole deviation)
Stuck pipe - 8,085 ft (stabilizer torque)
Fishing - back-off, spear, 4 trips (7 days)
Logging - problem running tool
Slim-Hole No. 3





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Plugged bit nozzles - 1,006 ft
Motor twist-off (stabilizer torque) - 7,071 ft
Fishing - 3 trips
Motor twist-off (stabilizer torque) - 1,004 ft
Fishing - 3 trips (23 hours)
Motor twist-off (stabilizer torque) - 5,187 ft
Fishing - 1 trip (grapple)
Lost cone - 10,871 ft (drilled with rock bit)
38
Unocal Thailand Slim-holes (1999)
Conventional
SSSV
Slimhole
13-3/8” @ 1000’
9-5/8” @ 4500’
SSSV
Ultra Slim
9-5/8” @ 850’
7” @ 2500’
SSSV
7-5/8” @ 850’
5-1/2” @ 2500’
6-1/8” Hole
4-3/4” Hole
2-7/8” TBG
@ 4500’
2-7/8” TBG
@ 4500’
2-7/8”
TBG
7” @ 10000’
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Unocal Thailand Slimholes (1999)
1.3
1.4
Well Cost ($millions)
1.2
1
0.8
0.75
0.6
0.4
0.2
0
Slimhole
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(4-3/4”)
Conventional
(8-1/2”)
40
Cumulative Gas Production (MMSCF)
Unocal Gas Production Rates (1999)
Slimhole Wells
Conventional Wells
0.00
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500
1000
1500
Time (days)
2000
2500
41
Unocal, 1997
“Slimhole development has completely
Transformed the future of Gulf of Thailand
Operations and has paved the way for
Operators to continue providing a longterm economic supply of gas to the
Kingdom of Thailand”
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Pemex Slimholes (1998)
Conventional
Slimhole
17-1/2 Drill Bit
150 m
13-3/8” Casing
12-1/4 Drill Bit
150 m
12-1/4” Drill Bit
1650 m
9-5/8” Casing
9-5/8” Casing
8-1/2” Drill Bit
1650 m
7” Casing
2-7/8” Tubing
3000 m
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Packer
Cement
8-1/2” Drill Bit
5-7/8” Drill Bit
7” Casing
3000 m
3-1/2” Tubing
43
Pemex Slimholes (1998)
45
42
Cost Savings (%)
40
35
32
31
30
30
25
20
16
15
13
12
Wellhead
Cement
10
5
0
Mud
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Rig
Casing
Time
Tubing
Bits
Overall
44
Texaco Dual Completion Slimhole
17-1/2 Hole
2,500’
13-3/8” Casing
12-1/4” Hole
8,000’
9-5/8” Casing
2-7/8” Tubing
10,500’
Cement
8-1/2” Hole
12,500’
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2-7/8” Tubing
45
Slim-hole Well Concerns
 Casing
Program
 Drillstring
 Fishing
& Milling
 Increased
 Bit
Torsional Strength
ECD (lost circulation)
Design and Reliability
 Downhole
Motors(cost & reliability)
 Cementing
(primary & squeeze)
 Stimulation
 Workovers
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Slim-hole Well Non-Concerns
 Logging
 Perforating
 Tubing
buckling & sticking
 Wellhead
 BHA
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design
design
47
Conclusions
Slimholes:
-Reduce Well Costs 40 to 70%
-Reduce Environmental Costs & Concerns
-Tools and Equipment Exist, and are
Available and Reliable
-Safe
-Do Not Usually Limit Production
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High-Power Slim Motors
Long Power Section
Universal Jt
Bearing
Pack
Standard
Power
Sections
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Leniek Pumping System (1999)
1-1/2” Hydraulic
Hose
Clamp
Production Line
Stuffing Box
Gas Vent
Hollow Polish Rod
3-1/2” Cemented Tubing
2” Coiled Tubing
Hollow Rod Pump
Screen
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Anchor
50
Leniek CT Pumping System
Conventional
Surface Equipment
1,000 to 5,000 Feet
2-7/8” or 3-1/2” Casing (CT or
Tubing)
1-1/2” CT (Hollow Sucker Rod)
Hollow Polish Rod
Hollow Rod Pump
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YPF Installation
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Leniek System Advantages
 Reduce
Well Construction Cost 50
Percent
 Eliminates Tubing Thread Failures
 Eliminates Tubing Anchors
 Reduce Lifting Costs
 Reduce Paraffin Problems
 Reduce Casing Wear
 Treat Wells Through CT
 Eliminate Rod Failures
 Allows Ultraslim Holes
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Advances in
Coiled-Tubing Technology
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Overview
 History
& Evolution
 Current
Status
 Conventional
 Coiled
Operations
Tubing Drilling (CTD)
 Outlook
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Publications on Coiled Tubing
Number of Publications
120
100
80
60
40
20
96
94
92
90
88
86
84
82
80
78
76
74
72
70
68
66
64
0
YEAR
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Evolution
1944
Allied Invasion Europe
1962 Bowen CTU
1975 - 200 Units - 1-1/4”
1980 - Improved Pipe/Welding
1983 - Continuously Milled 3000’
1987 - Bias-Welded Strips
1992 - 2-3/8” to 3-1/2” OD CT
1999 - 110 ksi CT
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Today
750
Units Worldwide
50%
Few
in North America
Pipe Failures
Multiple
CT
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Applications
Pipelines
58
Common Applications
Clean
outs (50%)
Stimulations
Profile
Modifications
Perf/Log
Artificial
Sand
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Lift
Control
59
Coiled-Tubing Applications
Clean-out
Downhole Tools
Stimulation
Nitrogen Lift
Drilling
Logging/Perf
Jetting
Fishing
Cementing
Source: Quality Tubing
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Cost Savings with Coiled Tubing
OPERATOR
ARCO Alaska
Fracmaster
BP (North Sea)
Chevron
Amoco (GOM)
BP Alaska
Mobil
Amoco
JOB
SAVINGS YEAR
Cement Squeeze
90%
1987
Pipeline Cleanout
90%
1988
Barium Scale
80%
1990
Velocity String
59%
1992
Zinc Sulphide
94%
1993
Spoolable GL
68%
1993
Fracturing
21%
1994
TT Gravel Pack
80%
1996
Workovers
Completions
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Support Pole
Hybrid Coiled-Tubing/
Snubbing Rig
(Hydrarig)
CT Injector
Injector Trolley
Substructure
Jack Cylinder
Quad BOP
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Oman Large-OD CT Completions
Taylor and Conrad (1996)
Slim Concentric
Water Injector
ESP Well
Slip
Connection
ESP cable
Slip connector
Landing nipple
Protector
Motor
Centralizer
7” K55, LTC
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Velocity String
Top CT plug
2-7/8” CT
1-1/2” CT
4-1/2”
Tie back
3-1/2” CT
Pump
Gas Lift Well
Gas lift
mandrels
13-3/8”
casing
4-1/2”
Tie back
2-7/8”
EU nipple
5-1/2” x 2-7/8”
production
packer
3-1/2”
tubing
Gas lift
mandrel
Bottom hole
press. gauge
Sliding
sleeve
circulating
device
7” packer
3-1/2” nipple
7” shoe
Hyd. set
retrievable
packer
Production
packer
2-7/8”
EU nipple
70
ARCO Coiled-Tubing Liner
Production tubing
Hydraulic set packer
Open-hole well
(possibly drilled with
coiled tubing)
CT liner
Pre-perforated
CT liner with
optional screen
Pay Zone
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CT Steam-Injection System
Coiled Tubing
Injector
Steam
Generator
BOP
Wellhead
Oil Reservoir
Steam
8000’
Pearlite
Oil
Oil
Steam
Casing
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Production
Tubing
Slotted
Liner
Concentric CT
2-7/8” CT
1-3/4” CT
Concentric CT
Cross Section
72
Coiled Tubing Drilling
(CTD)

History of CDT

Current Status

Demographics of Current Activity

Advantages and Limitations

Where are we headed with CTD?
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Coiled-Tubing Drilling System
Injector
Reel
Power Supply
2” CT with Wireline
Connector
Guidance
System
Whipstock or
Cement Plug Orienter
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Mud
Motor
Bent Sub
Bit
74
Why CTD or Why Not ?
 Continuous
Circulation
 Pressure Control
 Footprint, Environmental
 LWD, Geosteering, Joystick Operation
 Deepenings, Side-Tracks
 Through-Tubing Capable
 Costs?
 Availability
 Acceptance
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Brief CTD History
 1991
- Elf/Dowell & ORYX/Cudd
 1992
- Arco first window & MWD
 1994
- First North Sea CTD wells
 1994
- Maersk 3000’ Horizontal well
 1995
- 200+ CTD Wells Worldwide
 1999
- 1200± CTD Wells
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Schlumberger Electrically-Controlled
CT Drilling System
2" CT
Drilling
Head
Logging/Steering
Sub
Bit
Electric
Orienter
Motor
7-Conductor
Wireline
Schlumberger “Viper” BHA
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Transocean Hydraulically-Controlled
CT Drilling System
2" CT
Connector
Hydraulic
Orienter
Check Valves/
Release Sub
Bit
Logging/Steering SubMotor
Monoconductor Wireline
1/4" SS Hydraulic Tubing
Transocean Dual-Capillary BHA
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Camco Electrohydraulic Umbilical
CT Drilling System
18 AWG
Conductors
Protective
Sheath
Hydraulic
Oil
3/8” x 0.65”
Hydraulic Tubing
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Thermoplastic
Insulation
79
Arco CTD History
 1990-Initial
interest for PRB ST
 1991-Initial
ST effort unsuccessful
 1992-94
Oklahoma Window Milling Tests
 1992-Successful
 1993-Prudhoe
ST in West Texas
program started
 1994-95
THUMS Efforts,
 1997++
Algeria, Indonesia, CA, NM...
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ARCO Summary (1999)
120
120
100
80
60
40
20
0
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1
Alaska
California New Mexico
1
Texas
3
Indonesia
1
Algeria
81
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Running 3 1/2” CTC after CTD
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Typical CTD Completion at PRB
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Bottom
Hole Assembly
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Surface Testing
17 PPG Fiber F/O Plug
Pilot Hole
Casing Exit
“One Step” Mill
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1999-2000 CTD Developments
 Thru
- 3-1/2” Tubing Operations
Over 30 Slimhole Operations To-date
Fluid Loss/ECD Concerns
Lower Density
Lower Polymer loading
Shale Stabilization Additives
Bi-center Bits
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PRB CTD Average Footage
1950
2000
1794
1800
1685
Average Footage
1600
1400
1204
1200
1000
800
817
600
400
200
0
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1995
1996
1997
1998
1999
105
Prudhoe Bay Summary
100 wells 1993-99
Average Cost
1995 - $990M
1996 - $1005M
1997 - $1165M
1998 - $1200M
1999 - $1375M
•Harder, Longer Reach Targets
•Avg. Production 1400 BOPD
•90% success
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Grissom Island
THUMS - Arco Project
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California CTD Project
 4/97-
Drilled 7 shallow vertical wells
 Fleet
Cementers CTU - unique design
 Used
2 7/8” OD CT, 4 3/4” PDMs
 Hole
size 6 to 6 1/2” holes, 1 to 9 1/2”
 Depths
 Total
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900-1000’ , Ran 3 1/2” casing
time 24 hours/well
114
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Indonesia
 Multiple
well program in NW Java Sea
 One
ST/ window through 9-5/8” csg- 1997
 870’
of 6-1/8” hole drilled w/ 2-3/8” CT
 Used
tinder barge rig as support
 Completed
with cemented 3-1/2” liner
 2nd
well discontinued after 500’ - shale
 3rd
well April - June 1998- lost hole - shale
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Offshore Indonesia
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Current Status of CTD
20
CTU’s capable of serious CTD
Less
than 10 CTU’s actively drilling
AK,
Oman, Canada, N. Sea,
Venezuela
Currently
active; Schl, Baker, BJ
Fleet
MWD,
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electric/hydraulic BHA’s
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Why CTD or Why Not ?
 Continuous
Circulation
 Pressure Control
 Footprint, Environmental
 LWD, Geosteering, Joystick Operation
 Deepenings, Side-Tracks
 Through-Tubing Capable
 Costs?
 Availability
 Acceptance
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What is the Future ?
 Underbalanced
operations
 All-electric CTD BHA
 Composite CT
 Pre-programmed, self guided BHA
 Smaller BHAs
 Through-tubing rotary drilling
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Fiberspar Composite Coiled Tubing
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Fiberspar Spoolable Products
 Production
Tubing - FS PT
Pipe - FS LP
 Coiled Tubing -FS CT (for Well
Servicing)
 Line
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First FS CT Field String
6500 Ft. Length, 1.5” OD
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FS CT Field Validation Trails
Halliburton
Energy Services
 To date, 6 - CO2
injection well
clean-outs with
acid stimulation
for Altura in W.
TX and Phillips
in NM

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FS LP First Commercial Application




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Altura, Levelland,
TX
40,000’ water
flood installation
2” ID, 1500-psi
WP Fiberspar
LinePipe used
Pipe shipped in
8,000 ft
continuous
lengths
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Mobile Spooling Unit
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Few Fittings
 Long
runs were
easily
accomplished with
few or no fittings
to account for
turns
 Several long runs
with multiple turns
were successfully
completed in a
single pull
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