Measurement of the flow properties and capillary pressure relationships of certain coals pertaining to underground coal gasification. Final report, September 1976--November 1977

Various measurements relating to the Darcian flow of liquids and gases through coal have been performed on a relatively large number of samples of bituminous and sub-bituminous coals. The former comprises the Pricetown (Pittsburgh Seam) coal and the latter includes surface samples from the Hanna and Gillette, Wyoming coals and subsurface samples from the Hanna IV site. The measurements include absolute permeabilities to gas and porosities as functions of overburden pressure. Numerous relative permeabilities to gas as functions of water saturation were obtained for all coals at a simulated overburden pressure of about 200 psig. Each of the three coals display distinctive, characteristic curves. The rate of the increase of permeability to gas, the absolute permeability, the porosity, and the shrinkage are all inverse functions of rank. A much smaller number of effective and relative permeabilities to water as functions of water saturation were obtained for the Pricetown and Hanna coals. We were unable to initiate water flows in the Gillette Coals even though these exhibit the highest absolute permeabilities to gas. Twelve samples cored at about 350 feet at the Hanna IV site were also tested. Six effective and relative permeabilities to gas curves were obtained as functions ofmore » water saturation at a simulated overburden pressure of 350 psig. Porosity measurements were made by water saturation at atmospheric pressure and by isothermal expansion of helium at varying confining pressures. The various dynamic measurements were also identified according to their structural orientation. The overall results provide necessary input data for the varius in-situ gasification models being developed through the Department of Energy.« less