Abstract: Geochemical Analogs of Hydrocarbon Reservoirs in the Appalachian and Illinois Basin

ZAGGER, GLENN W.

Near surface direct and indirect geochemical survey methods can be used to detect hydrocarbon occurrence in a variety of settings. Analog surveys have been conducted over producing wells in the Appalachian and Illinois Basins. These near surface surveys primarily consist of a nine component soil gas hydrocarbon analysis, as well as a number of indirect methods including the use of Eh, pH, conductivity and microbial measurements. When designed with enough sample acquisition points and sufficiently close spacing, these surveys help define extents of producing fields. More importantly however, these analog surveys over known producing horizons yield data that can be utilized in understanding the results of exploration and development programs conducted in the region. These analog comparative studies combine statistical and compositional analysis to enable characterization of reservoir attributes. The use of ethane/propane and isobutane/butane ratios can aid in the discrimination of regional reservoir characteristics. The data derived from analog comparison studies also enables discrimination between reservoir hydrocarbon signatures and non-reservoir, `background' signatures within that region. This discrimination enables a greater degree of confidence in the interpretation of anomalous results from a near surface geochemical survey.

AAPG Search and Discovery Article #90939©1997 AAPG Eastern Section and TSOP, Lexington, Kentucky