The goal is to reduce uncertainty and increase success in frontier and emerging deep formation gas plays, by evaluating the current state-of-the-art in stimulation technology for deep and/or high temperature formations via: 1) a comprehensive literature review and industry interviews, 2) evaluating rock mechanics issues, 3) studying fracture growth behavior in deep formation completions, and 4) performing three to five small case studies evaluating stimulation in key deep formations.
Pinnacle Technologies Inc. – Project management and all research products
Gas Technology Institute Information Center – Literature search assistance
Spears and Associates (SAI) – Industry survey assistance
IHS Energy Group (HIS) – Database purchase
San Francisco, California 94103
Houston, Texas 77090
The U.S. Department of Energy’s (DOE) Deep Trek Program is targeted to improving the economics of drilling and completing deep (>16,000 feet) and/or high temperature (>350EF) and high pressure (>10,000psi) (HTHP) natural gas wells in the U.S. This effort is focused on the second objective of the Deep Trek program – improved Economics in Deep Well Completions. The objective of the work is to review current and past stimulation activity and research results for deep and/or HTHP well completions and stimulations in the United States. The information will develop and extend the knowledge base for the U.S. DOE and industry in the U.S. and Gulf of Mexico (GOM). The results will help reduce uncertainty and increase success in frontier and emerging deep and HTHP formation plays in the U.S. and GOM. The project shall provide the U.S. DOE and U.S. gas industry with an assessment of:1) what is currently working in deep and HTHP formation stimulation and completion technology, 2) what is currently not working in deep and HTHP formation stimulation and completion technology, and 3) what needs improvement in deep and HTHP formation stimulation and completion technology.
The initial phase of the project consisted of assessing deep gas well drilling activity (over the 1995-2007 time period) and performing a region-by-region industry survey of deep gas well stimulation practices. Of the 29,000 oil, gas, and dry holes drilled in 2002, about 300 were drilled in the “deep” well depth and/or temperature range. Of these, 25 percent were dry, 50 percent were HTHP completions and 25 percent were simply deep completions. South Texas had about 30 percent of these wells, Oklahoma 20 percent, Gulf of Mexico Shelf 15 percent and the Gulf Coast about 15 percent. The Rockies represent only two percent of deep drilling. Of the 60 operators who drill deep and HTHP wells, the top 20 drill almost 80 percent of the wells. Six operators drill half the U.S. deep wells. Deep drilling peaked at 425 wells in 1998 and fell to 250 in 1999. Drilling is expected to rise through 2004, after which drilling should cycle down as overall drilling declines.
Deep resources represent approximately 158 tcf (at depths greater than 15,000 feet), and are one of the sources of natural gas that will play an important role in meeting the growing need for natural gas in the United States. The Energy Information Agency estimated seven percent of U.S gas production came from deep formations in 1999. This contribution is expected to increase to 14% by 2010. Much of this deep gas production will come from the Rocky Mountain, Gulf Coast, and GOM sedimentary basins. The challenges of drilling and completing deep high temperature and high pressure wells are significant. Rock mechanics are not well understood at deep, high pressures. This project is to help provide some of that understanding.
The evaluation of rock mechanics issues related to stimulation of deep wells yielded a number of recommendations, including:
The case studies developed for this project included an analysis of three deep gas productive targets in the Table Rock Field near Sweetwater, Wyoming (a higher permeability dolomite layer flanked by thick, low permeability sandstones at Lower Weber and Upper Weber) at a depth of roughly 17,300 to 18,100 feet.
Complex hydraulic fractures will pose great challenges for treatment execution and economic well performance in deep HPHT reservoirs.
The last workshop was held in Norman, Oklahoma on February, 23, 2005. The final report is available on request.
Final Report Part 1 - December, 2005 - Report split into two parts to facilitate downloads
Final Report Part 2 - December, 2005
Wolhart, Steve; Rogers, John and Spears, Richard; "Deep Gas Drilling in the United States," Hart's, Drilling, March 2004
Rogers, John D., Lambert, Stephen L. and Wolhart, Steve; "Deep Drilling and Completion Technologies and Challenges," GasTIPS, Spring 2004
Mayerhofer, Michael, StephenL. Wolhart and John D. Rogers; “Results of U.S. Department of Energy Deep Gas Well Stimulation Study,” paper SPE 95639 presented at 2005 SPE annual Technical conference and Exhibition, Dallas, 9-12 October 2005.