The project goal is to provide reservoir-specific geological and engineering analyses of the emerging Green River Formation (GRF) tight oil plays in the Uinta Basin, and the established, yet understudied Cane Creek shale (and possibly other shale units) of the Paradox Formation in the Paradox Basin.
Utah Geological Survey, Salt Lake City, Utah
Energy and Geoscience Institute (EGI), University of Utah, Salt Lake City, Utah
Eby Petrography & Consulting, Inc., Denver, Colorado
Uinta Basin Petroleum Companies: Anadarko Petroleum Corp., LINN Operating, Inc. (Berry), Bill Barrett Corp., Newfield Exploration Co., QEP Resources, Inc., EOG Resources, Inc.
Paradox Basin Petroleum Companies: Anadarko Petroleum Corp., Fidelity Exploration & Production, SM Energy Co., Southwestern Energy, Castleton Commodities International
Other: U.S. Geological Survey (USGS), University of Alberta, Colorado School of Mines
The 2009-2014 high price of crude oil, coupled with lower natural gas prices, generated renewed interest in exploration and development of liquid hydrocarbon reserves. Following on the success of the mid-2000s shale gas boom and employing many of the same well completion techniques, petroleum companies started exploring for liquid petroleum in shale formations. In fact, many shales targeted for natural gas include areas in which the shale is more prone to liquid production. In Utah, organic-rich shales in the Uinta and Paradox Basins have been the source of significant hydrocarbon generation, with companies traditionally targeting the interbedded sands or carbonates for their conventional resource recovery. Because of the advances in horizontal drilling and hydraulic fracturing techniques, operators in these basins started to explore the petroleum production potential of the shale units themselves.
The GRF in the Uinta Basin has been studied for over 50 years, since the first hydrocarbon discoveries. However, those studies focused on the many conventional sandstone reservoirs currently producing oil and gas. In contrast, less information exists about the more unconventional crude oil production potential of thinner carbonate/shale units, most notably the Uteland Butte member, but also the black shale facies, deep Mahogany zone, and other deep Parachute Creek member high-organic units.
The Cane Creek shale of the Paradox Basin has been a target for exploration periodically since the 1960s and produces oil from several small fields. The play generated much interest in the early 1990s with the successful use of horizontal drilling. Recently, the USGS assessed the undiscovered oil resource in the Cane Creek shale of the Paradox Basin at 103 million barrels at a 95 percent confidence level and 198 million barrels at a 50 percent confidence level. Nonetheless, limited research has been conducted or published to further define the play and the reservoir characteristics.
The specific objectives of the research are to: (1) characterize geologic, geochemical, and geomechanical rock properties of target zones in the two designated basins by compiling data and analyzing available cores, cuttings, and well logs; (2) describe outcrop reservoir analogs of GRF plays (Cane Creek shale is not exposed) and compare them to subsurface data; (3) map major regional trends for targeted intervals and identify “sweet spots” that have the greatest oil potential; (4) reduce exploration costs and drilling risks, especially in environmentally sensitive areas; (5) improve drilling and fracturing effectiveness by determining optimal well completion design; and (6) reduce field development costs, maximize oil recovery, and increase reserves. The project will therefore develop and make available geologic and engineering analyses, techniques, and methods for exploration and production from the GRF tight oil zones and the Paradox Formation shales where operations encounter technical, economic, and environmental challenges.
The detailed reservoir characterization and rock mechanics analyses will provide the basis for identification of “sweet spots” and improve well completion strategies for these undeveloped and under-developed reservoirs. The project will provide (1) improved and detailed reservoir characterization of the GRF tight oil plays in the Uinta Basin and the Paradox Formation shale oil plays (in particular the Cane Creek shale) in the Paradox Basin, targeting specific, brittle, high potential intervals, and (2) improved methods for identification of “sweet spots” using methods such as epifluorescence analysis of regional well core and cuttings. The reservoir characterization and analysis will be based on newly acquired and donated core, well logs, and well cuttings, which will be used to improve well placement and establish a relationship between natural fractures and productivity; thus reducing the number of wells and the environmental impact of drilling. Analysis of in situ stress, using geophysical and other geomechanical data, will be used to improve hydraulic fracture design for development of new fields or expanding established fields. The project will provide operators with the information they need to reduce exploration and development costs and drilling risks while maximizing oil recovery and increasing reserves.
The first major task of this project was to locate and describe all available cores from the two primary target intervals in the Uinta and Paradox Basins. Project team members located and described in detail 13 Uteland Butte member cores and collected all associated data. These data are being used to develop a regional geologic picture of the Uteland Butte play. Project team members also described five cores from the Cane Creek shale in the Paradox Formation via high-resolution X-Ray fluorescence data, RockEval analyses, X-Ray diffraction, and other core analyses.
Four collaborations have been set up to help further explore both the Uteland Butte and the Cane Creek tight oil plays. The project team has (1) collaborated with Dr. Hans Machel, geology professor at the University of Alberta and renowned dolomite expert, to explore the origin of the Uteland Butte’s productive dolomite intervals and subsequent diagenesis; (2) collaborated with Dr. Joseph Moore, research professor at the Energy and Geoscience Institute, University of Utah, and renowned fluid inclusion expert, to study fluid inclusions in the Cane Creek shale to help determine timing of fractures and oil generation; (3) collaborated with research geologists from the U.S. Geological Survey to study the origins of Green River oils and thermal maturity of Green River shales; and (4) collaborated with Dr. Rick Sarg, carbonate geologist at Colorado School of Mines, to study the eastern extent of the Uteland Butte in the Uinta Basin.
TerraTek, a Schlumberger company, has completed all geomechanical testing on cores from the Uteland Butte and Cane Creek tight oil formations. This newly acquired data will be used to help determine reservoir mechanical properties and help optimize well completion strategies in both the Uteland Butte and Cane Creek plays.
Over the course of the project, the research team has given 13 presentations at both regional and national AAPG meetings. The team also recently hosted a core workshop for industry professionals interested in the Green River Formation of the Uinta Basin.
The project officially concluded on March 31, 2017, and a final report will be delivered to NETL by August 31, 2017. Several research papers have already been published and several more are in draft form:
including subcontractor cost-share: $184,348