Geohydrology of the Piceance Creek Basin, Colorado

Abstract

This paper was prepared for presentation at the 47th Annual Fall Meeting of the Society of Petroleum Engineers held in San Antonio, Tex., Oct. 8–11, 1972. 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 who the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. 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 discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. The Piceance Creek basin of northwestern Colorado (Fig. 1) is a topographic and structural feature of early Tertiary age. The potential development of an oil shale industry potential development of an oil shale industry within the basin and its need for a dependable source of both brackish and fresh waters has prompted a study of the subsurface water prompted a study of the subsurface water resources of this and to semiarid region. Prior studies by the USGS have indicated that Prior studies by the USGS have indicated that there is in excess of 2.5 million acre ft of water in storage within the leached zone aquifer in the basin. Published hydrologic data, such as pump tests and water quality for the deep aquifer, is almost nonexistent, although a large number of oil and gas and oil shale test holes have been drilled. The few available temperature logs within the basin suggested that there was considerable water movement within these holes at the time the logs were run. In the absence of any other readily available water data, we developed our own temperature logging equipment and ran logs in as many uncased holes as we could find open. The resultant data shows a subsurface flow from southeast to northwest across the basin. The temperature log, as we currently know it, has many uses throughout the oil and gas industry and has become quite sophisticated in its approach to production problems. It is particularly useful in an air-drilled hole, particularly useful in an air-drilled hole, such as an oil shale core hole where there has been no mud damage and the hole has been left open for further testing purposes. Due to lost circulation problems in the shallow zones, air drilling has been popular in the basin in recent years. These temperature logs are of particular value in showing the hydrologic particular value in showing the hydrologic regime within any given borehole and also can be used as an exploratory tool to evaluate water movement within an area of thick or multiple aquifer development where there is little existing data, such as in the Piceance Creek basin. If each and every temperature log run within this basin had exhibited a normal gradient curve, we would have a basin in which all aquifers were in equilibrium with each other and, as a result, there would be little or no fluid movement and consequently no reason for this paper. Fortunately, the basin is under anything but equilibrium conditions, and there is lots of water movement. The log can be run at any time after a hole has been drilled, but a better interpretation of basin conditions can be obtained after the well has been left undisturbed for a year or more to allow it to reach equilibrium. This is the case for most of the wells within the basin. Let us digress briefly and establish the geologic framework of our aquifer systems.

Environmental Implications of Oil-shale Development

“…Towards the centre of the Basin, to the north of the Colony tract, the area drains northwards to the White River, and ground-water aquifers are extensive (Coffin et al, 1971;Tait, 1972; U.S. Geological Survey, 1974) and appear to be items of concern in the mining operation. At the lease tracts, C-a and C-b, for example, there is a freshwater aquifer above the Mahogany zone (a prominent volcanic layer in the shale over much of the Basin) and a lower-quality aquifer below this zone.…”