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AOGCC approves Aurora EOR On reconsideration, enhanced oil recovery approved at Prudhoe satellite Kristen Nelson Petroleum News Editor-in-Chief
The Alaska Oil and Gas Conservation Commission has approved BP Exploration (Alaska)'s plan to use miscible injectant for enhanced oil recovery at the North Slope Aurora Oil Pool after initially denying it. BP got approval May 6 after submitting additional written materials. The commission also cancelled a hearing, saying BP submitted documents “sufficient to rule on the merits of the application without need for a further oral hearing.”
In another action on the same Prudhoe Bay satellite pool, the commission issued revised Aurora pool rules May 15. This was an action the commission carried out on its own volition.
BP applied for a modification of the Aurora oil pool area injection order to allow for injection of miscible injectant for enhanced oil recovery in December. The commission rejected that application in April over concerns that reservoir pressures were below minimum miscibility pressure in at least one of the blocks at Aurora and possibly in portions of two others. The commission also said production and waterflood at Aurora were not being conducted “in a manner consistent with testimony provided” when BP applied for pool rules in the area.
The commission said BP's “current reservoir management strategy is unclear” and asked for a comprehensive reservoir plan for Aurora which would address “water injection and re-pressurization of the reservoir in preparation for miscible gas injection to ensure greater ultimate recovery of the oil in place” at Aurora. EOR planned for second quarter Tract operations began at Aurora in November 2000 and the commission approved water injection in 2001. BP's EOR proposal is for water injection alternating with miscible gas injection beginning in the second quarter of 2003. BP estimates that additional recovery with miscible gas injection will be 3-5 percent of original oil in place.
In its May 6 approval the commission said it denied the original application because BP did not submit sufficient technical data to demonstrate that the miscible injectant “would remain miscible throughout the planned flood area.” The commission said BP “fully addressed the concerns” when it applied for re-hearing in late April. Miscible gas injection will begin where water injection has been established, in the West and North of Crest blocks. The commission said water injection has recently increased and “is equal to or slightly exceeds reservoir withdrawal” in those blocks.
The commission also said that BP reservoir studies showed “insignificant reserve loss from delayed waterflood” at average reservoir pressures above 2,400 pounds per square inch. It concluded that current average reservoir pressure is above 2,700 psi, and said enriched gas would remain miscible “provided the average reservoir pressure remains above this pressure.”
BP had also requested approval of lean gas injection to maintain reservoir pressure. The commission did not approve that request, saying information provided was insufficient to show the impact of lean gas on ultimate recovery. It said BP could seek approval for lean gas injection “at a later date when plans and recovery benefits are better defined.” Additions to Aurora pool rules The commission issued revisions to Aurora pool rules May 15. The commission is requiring a monthly report showing daily allocation data and daily test data for the Prudhoe western satellite production metering plan. It also noted that approval of that plan expires Aug. 31, and said it will determined continued authorization of metering and allocation procedures at a hearing no later than July 31.
The pool rules are also changed to reflect approval of water and miscible gas injection at Aurora. The commission said miscible gas injection outside of North of Crest and West blocks (approved in the injection order) must be approved “prior to long-term injection.”
The commission is requiring review of pool production factors and issues as part of a previously required annual reservoir surveillance report and a discussion of BP’s reservoir depletion plan and status of reservoir re-pressurization activity as part of the annual plan of operations and development.
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