Abstract: Instrumentation for Evaluation of In-Situ Recovery Projects

D. Davis, J. Lytle, P. Kasameyer

In-situ recovery techniques, such as coal gasification and oil-shale retorting, are currently under investigation at Lawrence Livermore Laboratory and elsewhere. Information about the size and location of the "burn" as a function of time adds greatly to the understanding of these processes. One way to obtain such information is through the use of thermocouples implanted at many points throughout the expected burn region. Unfortunately, thermocouples sample only small volumes and fail at the high temperatures encountered in such processes. We have developed a technique of high-frequency electromagnetic mapping (HFEM) which has been successful in following the progress of a burnfront during an underground coal-conversion experiment.

During an experiment at Hoe Creek, Wyoming, the HFEM technique successfully detected and followed the vertical position and extent of the burnfront between each of several pairs of wells during the 72-day burn. Seven wells located at the expected perimeter of the burn region were available for transmitting and receiving antennas. The transmissivity of the coal to radio-frequency waves was determined as a function of depth by lowering the two antennas in unison. Regions occupied by the burnfront were more opaque to the electromagnetic waves.

AAPG Search and Discovery Article #90961©1978 AAPG Annual Convention and Exhibition, Oklahoma City, Oklahoma