This work shows that effective well damage determination from pressure buildup tests in complex, developed reservoirs may be best achieved through early time data analysis. Extensive analysis was done using field data from the Prudhoe Bay reservoir in Alaska· Conventional Horner analysis is largely ineffective in this reservoir because of distortion of the late time data by boundary effects. The early time data are affected by partial completion of a large net pay zone. Five different analysis techniques were used to analyze the pressure buildup data. Results from these methods were correlated with production histories and scale damage removal treatments on thirty-two Prudhoe Bay wells. A radial implicit simulator was also used to history match the pressure behavior in several buildup tests to verify the analytic results.

It was found that the McKinley Early Time Analysis Method, modified for partial completion, provided the most reliable estimate of well damage at Prudhoe Bay. The method can provide a qualitative indication of well damage in the presence of a constant-pressure boundary (the gas cap at Prudhoe Bay). The more reliable estimates of well damage allowed us to plan a more effective well stimulation treatment program.

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