Results of U.S. Department of Energy Deep Gas Well Stimulation Study

Abstract

Abstract The paper reports on a U.S. Department of Energy sponsored project to evaluate deep gas well stimulation (Deep Trek Program). Under the Deep Trek Program, this study was conducted to evaluate the stimulation of deep wells onshore U.S. and Gulf of Mexico Shelf. The objective of the project was to assess U.S. deep well drilling & stimulation activity, review rock mechanics & fracture growth in deep, high pressure/temperature wells and evaluate stimulation technology in several key deep plays. This paper documents the location and level of deep gas development in the near future, discusses important issues and technology needs, and presents case histories of current stimulation practices for selected fields. The challenges of drilling and completing deep gas wells are quite significant. Relatively few deep wells (>15,000 feet true vertical depth) are drilled annually. Of the estimated 29,000 wells (oil, gas and dry holes) drilled in U.S. in 2002, approximately 300 were deep wells. Deep drilling peaked at 425 wells in 1998 and fell to 250 wells in 1999 as part of the overall industry downturn. However, successful deep gas wells can be prolific producers and it is projected that natural gas from deep reservoirs will be essential to meeting future domestic supply demand. The study included a review of deep gas well drilling activity (historical from 1995) and forecast through 2009. Interviews were conducted with operators, service companies and consultants on deep gas well stimulation practices and technology needs by region. Also, key issues with rock mechanics and fracture growth in deep reservoirs were summarized. The following two areas include case studies documented in the paper: South Texas (targeted due to current and future drilling activity); six wells completed in the Lobo sands in Zapata County,Rocky Mountains (targeted due to the huge deep gas resource in place); five wells completed in the Lower and Upper Weber sandstones and Weber Dolomite in the Wamsutter area of Wyoming.