Baram Delta Operations (BDO) consists of a collection of nine producing oil fields located offshore Miri, Sarawak, Malaysia and operated by Petronas Carigali Sdn Bhd (Sarawak Operations). Production wells typically comprise dual strings with each string being completed with a single internal gravel pack straddling several producing intervals. In some strings high water production from a particular interval retards oil production from the other intervals by reducing vertical lift efficiency and in these cases water reduction technology was evaluated as a potential oil stimulation technique. Due to the completion configuration, PLT assessment could be of limited value and selective placement of plugging chemicals into target intervals was not considered a viable option. Thus despite the higher degree of uncertainty associated with the use of chemicals designed to selectively reduce water permeability (with little or no impact on oil permeability), these were considered the only viable option for potential application within BDO. Based upon independent confirmation of vendor submitted core flow test data, a linear, amphoteric polymer system was selected for field testing. The results of the core flow tests suggested that for intervals of high water saturation, treatment with the linear, amphoteric polymer system could reduce water permeability by about an order of magnitude while in intervals of high oil saturation, relative permeability to oil would be largely unaffected. Despite the highly encouraging laboratory results, an initial two well field test programme failed to prove the technology in the field. While the first field test failed due to operational difficulties, the second was a clear operational success but did not lead to reduced water production. Despite intensive post job analysis, the very wide discrepancy between the laboratory and field results has yet to be satisfactorily explained.

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