Abstract

Thick Frontier and Adaville Formation coals are found in the subsurface of eastern Summit County in T. 2 and 3 N., R. 9 E., Salt Lake Base Line and Meridian. Although considered part of Utah’s Henrys Fork coalfield, these coals are an extension of the thrust-bounded, north-south trending Hams Fork coal region of southwestern Wyoming. Utah’s Frontier and Adaville Formation coals are not exposed, but are known from geophysical logs and drill cuttings from two abandoned petroleum wells.

Well logs for Amoco Production Company’s Champlin 436 A No. 1 well (section 3, T. 2 N., R. 9 E.) show 18 coalbeds in the Frontier Formation greater than 1 foot thick, and a total coal thickness of about 111 feet; the coals are found over a 1,400-foot vertical interval at depths ranging from 3,600 to 5,000 feet. Vitrinite-reflectance values for these Utah coals are probably suppressed and consequently do not provide a reliable indication of coal rank. Frontier coals in Wyoming are high volatile bituminous in rank and data from abandoned, underground mines indicate they contain methane.

Well logs for Amoco’s Champlin 434 A No. 1 well, located in section 15, T. 3 N., R. 9 E., show 44 coalbeds in the Adaville Formation ranging in apparent thickness from 1 to 35 feet, and with a total thickness of 273 feet; the coals are found over a 1,600 foot vertical interval at depths ranging from 1,300 to 2,900 feet. Vitrinite-reflectance measurements indicate that Utah’s Adaville coals are high volatile C bituminous rank and are higher in rank than the subbituminous Adaville coals mined near Kemmerer, Wyoming. As with the Wyoming coal section, Utah’s Adaville coals increase slightly in rank from top to bottom of the section. Besides thermogenic gas, Utah’s Frontier and Adaville coals could contain biogenic gas similar to productive coals of Powder River coal region in Wyoming.

This potential coalbed gas prospect has several attractive features other than the presence of thick, possibly gassy coals at moderate depths. These coals are found in a favorable geologic setting, near gas pipelines, and under private lands.