Preliminary report on the geology, geophysics and hydrology of USBM/AEC Colorado core hole No. 2, Piceance Creek Basin, Rio Blanco County, Colorado

Abstract

Approximately 1,400 feet of continuous core was taken.between 800-2,214 feet in depth from USBM/AEC Colorado core hole No. 2* The drill site is located in the .Picean.ce Creek basin, Rio Blanco County, Colorado* From ground surface the drill hole penetrated 1,120 feet of the Evacuation Creek Member and 10094 feet of oil shale in the Parachute Creek Member of the Green River Formation* Oil shale yielding more than 20 gallons.per ton occurs between 1,260-2,214 feet in depth* A gas explosion near the bottom of the hole resulted in abandonment of the exploratory hole which was still in oil shale* The top of the nahcolite zone is at 1,693 feet. Below this depth the core contains common to abundant amounts of sodium bicarbonate salt intermixed with oil shale 0 .The core is divided into seven structural zones that reflect changes in joint intensity, core loss and broken core due to natural causes* The zone of poor core recovery is in the interval between ls 300-1,450 feet. Results of preliminary geophysical log analyses indicate that oil yields determined by Fischer assay compare favorably with yields determined by geophysical log analyses. There is strong evidence that analyses of complete core data from Colorado core holes No. 1 and No.. 2 reveal a reliable relationship between geophysical log response and oil yield. The quality of the logs is poor in the rich shale section and the possibility of repeating the logging program should be considered* Observations during drilling, coring, and hydrologic testing of USBM/AEC Colorado core hole No. 2 reveal that the Parachute Creek Member of the Green River Formation is the principal aquifer and the water in the Parachute Creek Member is under artesian pressure. The upper part of the aquifer has a higher hydrostatic head than, and is hydro logically separated from,, the lower part of the aquifer. The transmissionity of the aquifer is about 3500 gpd per foot* The maximum water yield of the core hole during testing was about 500 gpnu Chemical analyses of water samples indicate that the content of dissolved solids is low, the principal ions being sodium and bicarbonate. Although the hole was originally cored' to a depth of 2,214 feet, the present depth is about 2,100 feet. This report presents a preliminary evaluation of dore examination, geophysical log interpretation and Ipiydrological' tests from the USBM/AEC Colorado core hole No. 2. The cooperation of the U.S. Bureau of (fines is gratefully acknowledged. The reader is referred to Carroll and others (1967) for comparison of USBM/AEC Colorado core hole No. 1 with USBM/AEC Colorado core hole No. 2.

A Stream‐Based Methane Monitoring Approach for Evaluating Groundwater Impacts Associated with Unconventional Gas Development

“…Regionally this member of the Green River Formation ranges from 60 to 680 m thick. Aquifer testing in Piceance Creek Basin, Colorado, of the Parachute Creek Member (the Colorado equivalent of the Middle Member in central Utah; Self et al ) yielded transmissivity values of 30–45 m 2 /d (Ege et al ).…”

Journal of Research of the U. S. Geological Survey, 1977, volume 5, issue 2

“…Good correlation can be expected between the C-35 electric log and the interpreted electric sections for VES 5 and VES 9. Ege, Carroll, and Welder (1967), in discussing core hole C-35, reported oil shale beginning at 1,120 ft (341 m), with the Mahogany zone bounded by the marker A at 1,220 ft (372 m) and marker B at 1,405 ft (428 m). A zone of poor core recovery (leached zone) existed from 1,300 ft (396 m) to 1,450 ft (492 m).…”

“…Models C and D show that the 500-fl-m layer at 800 ft (268 m) can be interpreted either as an oil shale horizon or not. In discussing core hole C-35, Ege, Carroll, and Welder (1967) place the highest recognizable oil shale at about 1,120 ft (341 m) but do not indicate the lithology of logged units above that level. Model C assumes that the high-resistivity section begins only at that level, decreased by 120 ft (37 m) because of the elevation difference between the sites of VES 5 and C-35, and that it is anisotropic.…”