The Geological Survey conducted a seven-hole core-drilling program in the Recluse Geologic Analysis Area, northern Campbell County, Wyoming, in 1975. The purpose was to acquire rock and coal samples to further evaluate the surface-minable coals of this area. In 1976 the Bureau of Land Management defined a portion of this area as an Energy Mineral Resource Inventory and Analysis Program reclamation study area and drilled an additional eight core holes. During the course of the 1975 drilling methane (CH 4 ) emissions were detected in all holes. The quantities ranged from very small amounts of methane (+0.1 percent) in the return drilling air to major flows estimated to be as much as 1,000,000 cubic feet per day. Methane in the return drilling air or fluid is a serious safety hazard to personnel and equipment. On the other hand, the methane might have economic value.

Open-File Report↗

USGS1977

Chemical analysis, physical property tests, and lithologic description of cores and cuttings of lignite and overburden rocks from an area near Watkins, Colorado

The data presented in this report represents analytical and testing information from cores drilled by the Geophysics Department, Colorado School of Mines, assisted by the U.S. Geological Survey. The drilling was done in conjunction with the establishment of a geophysical testing facility by the Colorado School of Mines. Location of the study area and drill holes is shown in Figure 1. A total of 15 holes were drilled and geophysically logged; holes 9-1 and 7-11 were cored, and attempts to core hole 3-1 were made, but the lignite was very incompetent due to weathering and oxidation and recovery was very poor. Lithologic descriptions of the cores and cuttings for holes 9-1, 7-11, and 3-1 are listed on pages 13-21. Calculationdbased on hole 9-1 indicate that of the total lignite zone, 56 percent consists of partings and 44 percent is lignite. These percentages were obtained by statistical analysis of the core description and natural gamma logs of the hole. The total thickness of the lignite zone in hole 9-1 is approximately 18 m.

Colorado↗