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Risk in Well Plugging & Abandonment by Twachtman Snyder & Byrd, Inc. September 2006

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.

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Risk in Well Plugging & Abandonment by Twachtman Snyder & Byrd, Inc. September 2006

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  1. Risk in Well Plugging & Abandonmentby Twachtman Snyder & Byrd, Inc.September 2006

  2. 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.

  3. Robert C. Byrd Over 30 Years in the Offshore Industry • Joined TSB in 1993 • Responsible for Risk and Liability Consulting Services • Educational Background: • 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

  4. Well Plugging & AbandonmentSummary

  5. WELL PLUGGING & ABANDONMENT • Rigless Method used predominantly in Gulf of Mexico & North Sea • Rig-based method used primarily on subsea wells

  6. Well P&A Objectives • Assure isolation of hydrocarbon zones • Protection of fresh water aquifers • Prevention of migration of fluids & gases

  7. 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.

  8. Well P&A - Rig vs. Rigless Step 1 Typical Wellbore Schematic

  9. Well P&A - Rig vs. Rigless Step 2 Bottom Plugs Set With Tubing Pulled Out of Hole

  10. Well P&A - Rig vs. Rigless Step 3 Balanced Plug on Rigless and Stopped Plug With the Rig

  11. Well P&A - Rig vs. Rigless Step 4 Rigless with Cut Casing and CIBP; Rig with Same but with a little more Casing Out of the Hole

  12. 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

  13. 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.

  14. Well P&A Cost Risk Example

  15. Drilling Rig Production Equipment Deck Quarters Power Generation Jacket Pipeline Piles Conductors/Wells OffshorePlatform Components

  16. Other Risk Issues in Well P&A

  17. 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).

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