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AOGCC sets conditions for BP well work Company wants to use cement to seal holes in the tubing of some old Prudhoe Bay wells to enable viable continued well usage Alan Bailey Petroleum News
The Alaska Oil and Gas Conservation Commission has issued an order setting specifications for BP applications for permission to inject cement into the inner annuluses of three old Prudhoe Bay wells. The company wants to use this technique, which does not require a drilling rig, to plug some holes in the well tubing, thus making it possible to bring the wells back into service in a viable manner.
The inner annulus is the space between concentric tubing in a well.
The wells in question are nearing the ends of their useful lives - BP told the commission that the use of a rig to replace the damaged tubing would not be economically viable and that repair of the wells using cement should result in significant additional oil production from the field. On the other hand, the cement plugs would move the wells closer to a final plug and abandonment status. Increased production would presumably result from access to hydrocarbons adjacent the wells, or through continued use of a well for water injection in support of oil production.
BP has been maintaining oil production at the aging Prudhoe Bay field, in particular through a large amount of non-rig well work. During a hearing on this new well repair proposal, BP officials told the commission that it has successfully been using this type of cement plugging technique to repair aging Prudhoe Bay wells for around 20 years.
Strict rules From a safety perspective, and to prevent loss of valuable hydrocarbons, the AOGCC has strict rules about the downhole design of wells, and about pressure monitoring in wells. A repair of the type that BP wants to carry out requires a waiver from some of the rules, without compromising the well safety. A particular issue with a cement repair is the potential pressure isolation of the lower part of the well tubing from pressure monitoring at the surface. BP told the commission that it has alternative downhole techniques that it can apply for pressure and integrity testing in the repaired wells.
On Feb. 9 the commission issued an order, specifying that BP must submit an application for sundry approval for any well repair of the type requested. The order specified rules for an acceptable application, including factors such as the minimum subsurface depth at which a cement repair can be applied and a required specification of well diagnostics for monitoring the condition of the well after repair.
BP questioned the practicalities of some of the commission’s documentation requirements. Subsequently, on March 9, the commission issued a revised order, addressing some of BP’s concerns.
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