Abstract

Mountain Fuel Supply Company and the U. S. Department of Energy are conducting a joint project to demonstrate production and recovery of methane gas from deep coal seams in the Book Cliffs coal field of central Utah. The objective is to drill three wells to depths near 3000 feet to determine if commercial quantities of gas can be produced, and then to install production facilities for injecting the gas into the Mountain Fuel Supply gas transmission system.

Two of the three wells have been drilled and testing has been initiated. Five coal seams were encountered at depths between 2681 and 3112 feet. Core samples were obtained and desorption measurements indicate gas contents up to 400 cu ft/ton. The gas is approximately 95 percent methane. Water influx tests were made and water pumping equipment is being installed. Plans are being formulated to hydraulically stimulate the principal coal seams with nitrogen foam to increase production.

Introduction

Mountain Fuel Supply Company, with joint funding from the Morgantown Energy Technology Center (METC/DOE), is conducting a joint project to demonstrate the economic feasibility of recovering methane from deep unmineable coalbeds in Utah. Different completion techniques and hydraulic stimulation methods are being used to improve the understanding of methane recovery technologies.

Sites for three demonstration wells were selected in Carbon County, Utah. The sites are in a coal field lying in the western 70 miles of an imposing physiographic feature known as the Book Cliffs, which is 185 miles in length. Coal seams are present along its entire length. The western end abuts the Wasatch Plateau and is about 120 miles southeast of Salt Lake City.

Data from the Bureau of Mines and the Utah Geological and Mineral Survey have shown coals from this field to contain relatively high volumes of methane gas. The three well sites were selected after carefully reviewing these data. Two of the sites are adjacent to one of Mountain Fuel's major transmission lines.

DRILLING AND WELL LOGGING

The first two of the three planned wells were drilled late in 1979. These two wells are spaced 1800 feet apart in the Whitmore Park area approximately 23 miles northeast of Price, Utah. The wells were drilled to depths of 3000 feet and 3177 feet. Coal was encountered between 2681 and 3112 feet. Because of the depth, location, and other factors, these coals are considered to be unmineable at the present time. Figure 1 is a coal log for Well No. 2, which is typical of the formations encountered in both Whitmore Park wells. The log shows the location and thickness of the coalbeds encountered and the surrounding formations. Only minor variations in thickness and location of the coalbeds exist between the two wells.

Five coal seams were encountered at Whitmore Park Well No. 2. They range in thickness from Park Well No. 2. They range in thickness from 2 feet to 13 feet. The shallowest seam is the Sunnyside, which consists of 4 partings varying from 2 to 7 feet thick. Rock Canyon and Fish Creek coals were found to be 5 feet and 2 feet thick, respectively. The Gilson coal is 13 feet thick, and the Kenilworth coal is 2 feet thick.

CORE SAMPLE TESTING

Core samples of each of the upper 4 coals were obtained and are being analyzed for gas content, ASTM rank, and permeability and porosity under in situ conditions.

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