Characterization and Analysis of Devonian Shales as Related to Release of Gaseous Hydrocarbons: Well C-2 Lincoln County, West Virginia

摘要

Mean value of hydrocarbon gases in the free space surrounding the shale is 49.3 percent of total free volume. This translates to 0.3 ft exp 3 of gas per ft exp 3 of shale. Hydrogen velues show a narrower distribution range, with amounts from 0.4 to 0.9 percent. Good correlations are found between the hydrocarbon gas values and total carbon and hydrogen contents. Increasing amounts of carbon and hydrogen are associated with higher values of hydrocarbon gas contents. Among the physical characterization data obtained are densities (bulk and true), porosity (calculated from the density data and determined with Hg-intrusion technique), surface areas, and permeabilities. Bulk densities vary between 2.55 and 2.82 g/cc with an average value of 2.68 g/cc. True density values range from 2.64 to 2.90 g/cc with an average value of 2.74 g/cc. Porosity values calculated from the density data and mercury intrusion technique are reasonably close. Mercury intrusion values vary between 2.7 to 6.1%. Very good correlations are observed between the bulk density and carbon and hydrogen contents. Higher carbon and hydrogen contents are associated with lower bulk density values indicating that major sources of carbon (and to some extent hydrogen) are organic in origin. Several shale samples analyzed using x-ray diffraction revealed that the major clay mineral phase in these shales are kaolin minerals whereas illite has been the major clay mineral phase in the majority of wells thus far studied. The absence of feldspathic and mica minerals also differentiate C-2 shales from those of other wells. (ERA citation 04:042325)