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U.S. Department of Energy
Office of Scientific and Technical Information

LLL in situ coal gasifiction program. Annual report Fiscal Year 1977, October 1976--September 1977. [Hoe Creek No 1 and 2]

Technical Report ·
OSTI ID:6875649

Our principal efforts were directed toward the gasification phase of Hoe Creek No. 1 and preparation for Hoe Creek No. 2. Before gasification is possible, the native coal bed permeability must be increased. Explosive fracturing was used to prepare the coal bed for Hoe Creek No. 1. During FY 1977, the fractured zone was dewatered; this was followed by several days of air-flow testing. The coal bed was ignited at 16:30 on Oct. 15, 1976, in a forward gasification mode. We had no problems with liquid plugging, but after one day of operation at high pressure (60 psig) and low flow (100 to 200 scfm), a sudden increase in flow to 2000 scfm) and a corresponding drop in pressure indicated that a major obstruction had blown or burned out. After that, temperature measurements placed the major portion of the burn at the top of the coal seam. This override had been predicted by postfracture measurements. Even though the override was severe, the gas quality was relatively high (100 to 150 Btu/scfm). When gasification ended, on Oct. 26, 1976, approximately 130 tons of coal (about 16% of that in the fractured zone) had been consumed. Operationally, the experiment was quite successful, and, although the coal recovery was not as high as originally hoped, we were able to operate in forward gasification with reasonable (73%) thermal efficiency. In Hoe Creek No. 2, we plan to prepare the coal bed with the linked-vertical-well process of reverse combustion. A two-process well design was adopted with well spacings of 60 ft. Most of the burn will be conducted with air, but a short steam-oxygen test is planned. The primary objective of Hoe Creek Experiment No. 2 is to determine the feasibility of reverse-combustion linking in a relatively homogeneous, water-saturated coal seam.

Research Organization:
California Univ., Livermore (USA). Lawrence Livermore Lab.
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
6875649
Report Number(s):
UCRL-50032-77
Country of Publication:
United States
Language:
English