An operator launched a“water shutoff”polymer development project for a monobore gas well completion in the Gulf of Thailand.The shutoff concept involved a conservative tubing pad application in which a water shutoff polymer technique was used to help prevent wellbore restriction by sealing off the target reservoir permeability zone.Job planning and careful laboratory testing were conducted to simulate bottomhole conditions.In 2009,the treatment was used to perform shutoff of the top water producing zone using bullheading.The design consisted of the shutoff treatment followed by a loss circulation material (LCM)to help ensure wellbore fluid placement in the designed positions and that the pressure response could be monitored from the surface.The shutoff operation was performed according to plan,and coiled tubing(CT)was used for cleanup after placing the shutoff treatment.As a result of well testing after the shutoff treatment,water production dramatically decreased by 50%,demonstrating the effectiveness of the technique in terms of safety,economics,and operation.A long-term monitoring program was established to evaluate the polymer’s seal-off performance for development of future field strategies. Since 2009,water production monitoring has proven that the shutoff polymer is one of the best solutions for long-term water shutoff in terms of safety,economics,and operation.This technique does not require mechanical sealing off of the perforations,making it more feasible for future well interven-tions.
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