SPE Drilling & Completion
Volume 27, Number 3, September 2012, pp.341-347

Summary

The Moccasin exploration well in the deepwater Gulf of Mexico (GOM) was suspended before reaching planned total depth (TD) because of the GOM drilling moratorium imposed after the Macondo blowout. The well design had to be significantly altered to meet the new worst-case discharge criteria required by the Bureau of Ocean Energy Management, Regulation, and Enforcement (BOEMRE) and to resume drilling while preserving a planned 10 5/8-in. hole size at TD for formation-evaluation purposes. To meet the worst-case discharge collapse criteria, the well must survive an uncontrolled blowout at the mudline (seawater gradient to the wellhead with a flowing-oil gradient from the wellhead to TD). Furthermore, the well must survive shutting in the blowout, leaving the well fully evacuated to oil from the wellhead to the flowing zone (maximum anticipated wellhead pressure with an oil gradient to TD below).

The Moccasin well's 13 5/8-in. liner had to be tied back to the wellhead to provide sufficient burst resistance for the case of full evacuation to oil. An exceptionally long 11 7/8-in. liner and a short 11 7/8-in. scab liner inside 13 5/8-in. casing were required to mitigate deep collapse risk of the 13 5/8-in. liner associated with a flowing, unrestricted blowout at the mudline.

© 2012. Society of Petroleum Engineers

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History

• Original manuscript received: 26 October 2011
• Revised manuscript received: 4 April 2012
• Manuscript approved: 10 April 2012
• Published online: 29 August 2012
• Version of record: 18 September 2012