OF-80-01 Geophysical and Lithological Logs from the 1979 Coal Drilling and Coring Program, Denver East (1/2° x 1°) Quadrangle


Geophysical logs from 20 drill holes; coals were analyzed for methane content of Laramie Formation coal and Denver Formation lignites. 74 pages. 19 figures. 5 tables. 1 plate (1:100,000). Digital PDF download. OF-80-01D

Excerpt from the Introduction:

The CGS conducted an exploratory coal drilling program in the Denver East 1/2° x 1° Quadrangle. The program was designed to evaluate the coal resources of the quadrangle, especially near the Denver Metropolitan Area.

Drill-site locations were determined after an extensive evaluation was completed of water well logs, oil and gas well logs, and coal and uranium exploration hole logs. … The holes were drilled in two different areas; the Antelope Flats – Deer Trail area which contains the Laramie Formation coals and the Watkins – Lowry area which contains the Denver Formation lignites.

Twenty holes were drilled and geophysically logged with a coal suite (single-point resistance, focused density, caliper, and natural gamma) logging tool. Hole number CGS-10c was cored continuously from 15 feet to 511.3 feet, and the remaining holes were drilled by conventional rotary methods. Core samples of the coal were obtained in twined holes at CGS-4 and CGS-5, and CGS-4C, CGS-5C and 10c were sent to the USGS for analysis.

Lithologies were compiled by the author from the core, the drill cuttings, and the geophysical logs. Similarity of the rock types permit the omission of full descriptions. Many lithologies have been combined in the descriptions to accommodate the reduced scale of the logs presented in this report.