With required mitigation, no significant adverse effects are expected from BP Exploration (Alaska)’s plan to develop its Liberty prospect off Foggy Island Bay on Alaska’s North Slope from the secondary drilling island at Endicott.
The U.S. Department of the Interior’s Minerals Management Service has released an environmental assessment and a finding of no significant impact on the project. There is a 30-day public review period before MMS makes a final determination whether to prepare an environmental impact statement and takes final action on the proposed development and production plan, the agency said in a Dec. 3 Federal Register notice.
The finding of no significant impact notes that by developing Liberty with ultra-extended-reach drilling from the Endicott satellite drilling island, six development wells will be drilled from an expansion of the satellite drilling island, a reduction of 17 from the original plan.
Because the project will be drilled “from the existing Endicott industrial complex” and because ultra-extended-reach drilling will be used, “many potentially adverse impacts to the human environment are mitigated,” MMS said.
The original project, for which an environmental impact statement was prepared in 2002, had a subsea sales oil pipeline, a new gravel offshore island for drilling and processing and required 23 wells.
MMS said the evolution in the plan from the original standalone project reflects, among other things, environmental mitigation, advances in ultra-extended-reach drilling technology, use of depth-mitigated 3-dimensional seismic data and advances in reservoir modeling.
The environmental assessment is based on a development and production plan BP submitted in April (see story in May 20 issue of Petroleum News at www.petroleumnews.com/pnads/801208341.shtml).
A modification submitted in October outlined redesign of the gravel mine site adjacent to the existing Duck Island mine site, an upgrade of the Sagavanirktok River bridge superstructure (vs. replacement of the entire bridge) and a preliminary construction plan for the bridge, the agency said.
Both oil and gasMMS said potential recoverable resources at Liberty include up to 105 million barrels of crude oil and up to 78.5 billion cubic feet of natural gas, including natural gas liquids.
“Liberty is one of the largest undeveloped light-oil reservoirs near North Slope infrastructure,” MMS said. The estimated recovery of 105 million barrels would be by waterflood and BP’s trademarked low-salinity enhanced oil recovery, LoSal™.
Production would be from one to four producing wells and one or two water injection wells. Oil would be sent from the Endicott satellite drilling island to the Endicott main production island for processing and then would be transported to the trans-Alaska oil pipeline via the existing Endicott sales-oil pipeline. Produced gas from the project will be used for fuel gas and artificial lift for Liberty; the balance would be reinjected into the Endicott reservoir for enhanced oil recovery.
Water for waterflood would be provided from the existing produced-water injection system available at the secondary drilling island, and augmented if necessary by seawater from the Endicott seawater treatment plant, MMS said. The LoSal™ enhanced oil recovery process to be employed during a portion of the waterflood will be supplied by a LoSal™ facility constructed on the main production island.
Alternatives considered for Liberty development include an offshore island, a drilling pad at Point Brower and a drilling pad at Kadleroshilik.
Both the environmental assessment and the finding of no significant impact are available online at www.mms.gov/alaska.