EFFECT OF VERTICAL DEGASIFICATION WELLS ON COAL SEAM GAS CONTENT REDUCTION AT THE OAK GROVE FIELD,BLACK WARRIOR BASIN,ALABAMA

摘要

This paper presents results from a case study evaluation of the impact that vertical degasification wells had on reducing the gas content of the Mary Lee Group coal seams inside and outside the perimeter of the 23-well grid pattern at the Oak Grove pilot coal seam degasification project site in Jefferson County, AL.Over the period 1977-1996,the cumulative natural gas production from the 23 wells totaled 4.33 Bcf. The long-term cumulative produced gas volumes of the interior and exterior grid pattern degasification wells were not noticeably different.This similarity suggests that,in general,wells at interior and exterior locations in the pilot degasification grid pattern had comparable drainage areas.Volumetric and material balance calculations indicated that 2.81 Bcf(65%)of the total produced gas volume originated from the 365-acre area inside the perimeter of the pilot degasification well pattern.The long-term degasification resulted in a 90%reduction in the gas content of the Mary Lee Group coal seams inside the perimeter of the pilot project well pattern and a 36%reduction in the gas content of the Mary Lee Group coal seams in a 1,000-ft-wide,459-acre area around the perimeter of the pilot project well pattern. 0428