Transcript Well P&A Risk - Marine Seminar

Risk in Well Plugging & Abandonment
by
Twachtman Snyder & Byrd, Inc.
September 2006
Twachtman Snyder & Byrd, Inc.
• Houston, Texas, based company founded in 1987.
• Provides project management, well P&A and
contracting services to the oil and gas industry.
• Specialized in decommissioning of offshore facilities.
• Consulting services for decommissioning planning
and liability assessment.
Robert C. Byrd
Over 30 Years in the Offshore Industry
• Joined TSB in 1993
• Responsible for Risk and Liability Consulting
Services
• Educational Background:
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B.Sc. Marine Engineering, US Coast Guard Academy
M.Sc. Ocean Engineering, Unv. of Alaska, Fairbanks
M.Sc. Structural Engineering, Unv. of California, Berkeley
Ph.D. Engineering, Unv. of California, Berkeley
Well Plugging & Abandonment
Summary
WELL PLUGGING & ABANDONMENT
• Rigless Method used predominantly in Gulf
of Mexico & North Sea
• Rig-based method used primarily on subsea
wells
Well P&A Objectives
• Assure isolation of hydrocarbon zones
• Protection of fresh water aquifers
• Prevention of migration of fluids & gases
General Well P&A Procedure
• Cement plug is placed below and across the
lowest production zone, tagged and tested.
• Cement plugs across all production zones
• All open annuli are plugged.
• Tubing cut approximately -100 m below the
mud line (BML) and the tree is removed.
• Production casing removed to -100 m BML.
• Surface cement plug is pumped into the casing
with top at -32 m BML.
Well P&A Rig vs.
Rigless
26" @ 804'
18-5/8" @ 1607'
13-3/8" @
4344'
Step 1
Typical Wellbore Schematic
4-1/2" Liner top
@ 9549'
9-5/8" @ 9945'
Perforations
4-1/2" @
10,545'
Well P&A Rig vs.
Rigless
RIGLESS
RIG
26" @ 804'
26" @ 804'
18-5/8" @ 1607'
18-5/8" @ 1607'
13-3/8" @
4344'
13-3/8" @
4344'
Step 2
Bottom Plugs Set With
Tubing Pulled Out of Hole
BOTTOM SQUEEZE
4-1/2" Liner top
@ 9549'
4-1/2" Liner top
@ 9549'
9-5/8" @ 9945'
9-5/8" @ 9945'
PERFORATIONS
4-1/2" @
10,545'
4-1/2" @
10,545'
Well P&A Rig vs.
Rigless
RIGLESS
RIG
26" @ 804'
18-5/8" @ 1607'
18-5/8" @ 1607'
300' INTERM EDIATE
CEM ENT PLUG
Step 3
13-3/8" @
4344'
Balanced Plug on Rigless
and
Stopped Plug With the Rig
13-3/8" @
4344'
BOTTOM SQUEEZE
4-1/2" Liner top
@ 9549'
4-1/2" Liner top
@ 9549'
9-5/8" @ 9945'
9-5/8" @ 9945'
PERFORATIONS
4-1/2" @
10,545'
4-1/2" @
10,545'
Well P&A Rig vs.
Rigless
RIGLESS
RIG
200' SURFACE
CEM ENT PLUG
W/ CIBP
26" @ 804'
18-5/8" @ 1607'
18-5/8" @ 1607'
300' INTERM EDIATE
CEM ENT PLUG
Step 4
13-3/8" @
4344'
Rigless with Cut Casing
and CIBP; Rig with
Same but with a little more
Casing Out of the Hole
13-3/8" @
4344'
BOTTOM SQUEEZE
4-1/2" Liner top
@ 9549'
4-1/2" Liner top
@ 9549'
9-5/8" @ 9945'
9-5/8" @ 9945'
PERFORATIONS
4-1/2" @
10,545'
4-1/2" @
10,545'
Performance Risk Issues in Well P&A
•Time lapse between well completion and P&A
Deterioration of hardware
Loss of, incomplete or inaccurate records
•Often performed long after platforms shut-in
•P&A personnel often know little about the wells
•Cost pressure: Not income generating
Risk Mitigation Factors in Well P&A
•Formations generally produced out, therefore
pressures not high.
•Systems and tools are available to deal with
any eventuality.
Well P&A Cost Risk Example
PDF of Well P&A Experience
1.4
X <= 0.765
5.0%
X <= 2.600
95.0%
InvGauss(0.89492, 1.86797) Shift=+0.49924
1.2
Data Characteristics
Mean: 1.394
Mode: 0.998
Median: 1.234
1
0.8
0.6
0.4
0.2
0
0.5
1
1.5
2
Actual Cost/Estimated Cost
2.5
3
3.5
Offshore
Platform
Components
Production Equipment
Drilling Rig
Deck
Quarters
Power
Generation
Jacket
Pipeline
Piles
Conductors/Wells
Other Risk Issues in Well P&A
Risk in Well P&A
Conclusions
•The performance risk in well P&A is primarily
economic: It is very difficult to estimate the cost
accurately for a single well.
•We can estimate the cost of multiple wells
probabilistically.
•These Risks Pale in comparison with the
uncertainty following a Catastrophic Event
(Hurricane).