This paper describes a simple method to identify, prioritize, and evaluate restimulation candidates in the Antrim Shale of the Michigan Basin. This work is being performed as part of an ongoing field-based Gas Research Institute (GRI) project investigating the Antrim Shale. There are between 500 and 1,000 Antrim Shale wells which could be candidates for restimulation due to previous screenouts and/or flowback problems, when sand consolidation material was not used. However, all of these wells might not benefit from restimulation, due to either poor reservoir quality or because the wells are already effectively stimulated. Based on historical results, we estimate the increase in reserves from restimulation could be between 50 and 400 MMscf per well, which could add 50 to 200 Bscf in future reserves from the 500-1,000 candidate wells.

We have developed a novel injection test unit and procedure to help operators identify the best restimulation candidates in a cost-effective manner and in a reasonable amount of time. The test is designed to determine if there is an effective hydraulic fracture connected to the wellbore. To our knowledge, a test of this nature has not been used before for specifically identifying restimulation candidates. To date, we have run 50 tests, and identified potential restimulation candidates from about 1/3 of the tests.

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