Hydrology of the Piceance Basin and Its Impact on Oil Shale Development

Abstract

This paper was prepared for the Rocky Mountain Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Casper, Wyoming, May 15–16, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract The Piceance basin is a structural downwarp in northwestern Colorado. The Green River formation, the uppermost stratigraphic unit in the basin, contains the richest oil shale deposits in the U. S. The near-surface rocks are commonly jointed. The joint density is a function of the competency and thickness of the individual layers, the lateral distance to a free surface, and the depth below the surface. These joints provide permeable paths for the flow of provide permeable paths for the flow of ground water. Consequently, soluble elements in the rock have been leached, thereby enhancing the transmissivity by fracture enlargement. Thus, the oil shale layers are part of the aquifer matrix, and the richest layers of oil shale occur between, below, or are part of the basin's complex aquifer system. part of the basin's complex aquifer system. Well over 1 million acre-ft of potable water are contained in the Green River ground-water system. In addition, substantial quantities of very saline water occur deep in the north central part of the system. The high transmissivities (up to 2,000 sq ft/D) and the large volumes of ground water present in and adjacent to the oil shale layers present in and adjacent to the oil shale layers force potential shale oil developers to carefully consider the impact of the hydrologic system on development techniques and costs. Potential oil shale development techniques include subsurface mining, strip or open pit mining, and in-situ recovery. In considering these techniques or combinations of them on a basin-wide program, we find that the hydrologic factors impact directly upon the predevelopment and development operations, as well as the spoils handling and wrap-up operations. We believe that the best technique for providing a minimum-cost water handling providing a minimum-cost water handling capability for the oil shale developers, as well as providing protection for the area water resources, would be to establish a central water development and control organization. Such an organization would coordinate water development, provide dewatering, water cleanup and disposal provide dewatering, water cleanup and disposal services, and regulate spoils handling so as to prevent subsequent large-scale contamination of prevent subsequent large-scale contamination of water flowing from the basin into the Colorado River system. Introduction It is generally recognized that domestic reserves of oil and gas (which supply 77 percent of our current energy needs) are becoming percent of our current energy needs) are becoming increasingly scarce. Price increases will spur domestic exploration for oil and gas. However, estimates of the extent of the impact of these yet undiscovered sources of supply are in time frames of decades and not centuries.