Results of the characterization of an in situ coal gasification site in the state of Washington

Abstract

Sandia Laboratories, Lawrence Livermore Laboratory, and the Laramie Energy Technology Center participated in a Department of Energy funded program to select and characterize a potential underground coal gasification test site in the State of Washington. A site in the Centralia-Chehalis coal district, satisfying certain criteria, was selected for characterization. The characterization procedures included surface and borehole techniques and hydrology tests. Geologic structure and coal seam structure and continuity were determined using surface geophysical prospecting (seismic and electromagnetic surveys) and borehole geophysical (logging and cross-borehole, inseam seismic) techniques. A complete suite of geophysical logs was taken in eight exploratory boreholes to determine lithology and properties of the coal and surrounding strata. Coal cores taken from four different exploratory boreholes were analyzed to determine coal quality. Results of the characterization show that the coal seam of interest is approximately 47 ft thick at a depth of 570 to 600 ft at the site. The seam is characterized by high ash content, relatively low overall heating value, and a low permeability. The site appears suitable for conducting an underground coal gasification test