A number of highly permeable oil wells in the Valhalla field require re-fracturing treatments to optimize production. However, occasionally re-fracturing treatments are unsuccessful because the wells appear damaged after the treatments.

Presented are the results of an extensive study of the probable damage mechanism, and remediation of a well in the Valhalla field. A carefully designed and conducted pressure buildup test yielded better estimates of near wellbore and formation properties than the conventional test. A numerical reservoir simulator is used in the case study to history match the measured pressure buildup data and predict production. The cause and extent of the damage were determined, thus allowing modifications to be made to future re-fracturing programs. The well was then stimulated successfully with a second re-fracturing treatment.

The methodology presented in this study is designed to aid petroleum engineers to understand the importance of applying well-designed and interpreted pressure transient tests, to assess critical formation behavior.

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