Two research projects to assess the oil shale potential of the Piceance Basin in northwestern Colorado are undergoing preliminary assessment by the Bureau of Land Management (BLM) in Colorado.
BLM’s White River Field Office (WRFO) is in the process of evaluating two nominations for the second round of leasing 160-acre tracts for oil shale research, development and demonstration (RD&D) over 10 years. Up to 480 continuous acres of preference lease areas are being reserved if the concept projects are completed and commercial operations were to move forward.
BLM already has completed one round of oil shale RD&D leasing, with environmental assessments (EA) on the “proof of concept” completed for projects by Chevron USA Inc., Shell Frontier Oil and Gas Inc. and EGL Resources Inc. BLM’s second-round preliminary EA covers a concept project by ExxonMobil Corp., as well as one by National Soda Holdings Inc. Both would be conducted in Rio Blanco County in the White River Basin of the state.
ExxonMobil proposes to test an in situ process to determine whether a commercially viable production enterprise is viable. The process involves converting oil shale kerogen underground to producible shale oil and gas.
Oil shale is not the same as shale oil. Oil shale comes from kerogen-rich rocks closer to the surface than shale oil formations. The rocks have to be heated to extremely high temperatures to convert the kerogen into oil. The economics and environmental concerns of oil shale are considerably different from those of shale oil.
“The relevant units for oil shale development include the Green River formation and its members, and the Uinta formation overlying the Green River,” ExxonMobil said in its proposal. The area consists of “shales, thin sandstones and limestones, and oil shale beds and bedsets.”
The main oil shale-bearing unit of the Green River formation, Parachute Creek, which is about 1,500 feet thick, is the target for ExxonMobil’s project. Up two 12 production wells and 12 additional monitoring wells would be drilled. Only “small volumes” of oil and gas, 75-175 boe/d, are expected to be produced after six months of production, not enough to support a commercial operation.
During pilot testing, peak produced volumes are estimated to be 400-700 boe/d, and again, not sufficient for commercial operation, said ExxonMobil. However, once the pilot is completed, the producer said if all goes to plan it would seek to convert the RD&D lease to a commercial lease.
National Soda also proposes to conduct an in situ process to convert kerogen on a small scale from the Green River formation oil shale to test the effectiveness of leaching and chemical conversion technology. Conventional vertical well technology initially would be used, while the second phase would use the company’s chemical conversion technology to liquefy the kerogen.
BLM will accept public comments on the preliminary EA through June 16 (DOI-BLM-CO-11–2011-0177-EA). Send written comments to Paul Daggett, BLM WRFO, 220 E. Market St., Meeker, CO 81641, or via email to firstname.lastname@example.org with “2nd Oil Shale RD&D EA Comments” in the subject line. Contact Daggett at (970) 878-3819.
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