Naturally fractured tight gas: Gas reservoir detection optimization. Quarterly report, January 1--March 31, 1997

Abstract

I 2. Current Technolofl. The well drilling at the assumed well spacing (1 60Nwell) and the EURs per well @cfilwell) under the Current Technology Situation (as described by the USGS) are provided in the second column of Table 5. A key technology assumption for Current Technology Situation, (used in the 1995 USGS National Assessment and also by the DOEEETC sponsored Scotia study) is that the exploration efficiency (the "b" value in the exploration efficiency equation) is 1, representative of random drilling and no selectivity. Thus, under Current Technology, the entire play would need to be drilled to exhaust the higher productivity portions of the basin. As a result, as set forth in the second column of Table 5 under Current Technology, 5,000 wells would be drilled into this 1,250 square mile gas play, at four wells per square mile. The average successfbl well would recover 0.9 Bcf and at the 55% success ratio set forth for the undeveloped portion of this play, the average well would recover 0.5 Bcf. This would provide the following resource estimates and economics for the Williams Fork tight sands: At 0.9 Bcf per successful well and a 55% success rate, the 5,000 to be drilled Williams Fork gas wells would provide 2.4 Tcf of technically recoverable gas resources from the southern Piceance Basin, consistent with the 4.9 Tcf estimated for the entire Piceance Basin by the USGS.