One of the key successes in optimising a mature offshore oil producing field with water drive mechanism is to actively unlock additional oil production from reservoirs that have not experienced water breakthrough while maintaining gross production from reservoirs that have started producing water. This can be achieved by drilling more infill wells to create additional oil drainage points; however this is a very capital intensive investment. The other approach is to perform stimulation jobs on existing wells (both idle and producing) as part of production enhancement activities to increase well productivities which are comparatively more cost effective. With the increase in well productivities, these wells can be produced at lower drawdown which can delay water breakthrough.
This paper describes a holistic approach from understanding well inflow productivity problem due to severe downhole asphaltene or wax deposition issues, formulating the right organic-solvent-mud-acid chemical recipe for the well stimulation jobs, selecting the appropriate well candidates, and optimizing offshore stimulation job execution to ensure good chance of success. The stimulation campaign for 3 wells was carried out between Dec 2009 and Jan 2010 and was proven to be very successful. The cost per job was reduced by 30% compared to previous stimulation job, oil production for all wells increased (including a well which is closed in for 10 years), and up to date, water production has not been observed. Finally, a post job detailed technical analysis was conducted to allow a better understanding on the chemical recipe performances for optimization of future stimulation jobs.
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