Geochemical Surface Anomaly Distribution Above Active Hydrocarbon Source Beds: Anadarko Deep Example

HARNETT, RICHARD A., Consultant, Tulsa, OK

Surface geochemical surveys were run on all available county roads across the deep part of the Anadarko basin in Caddo, Custer, and Washita Counties, Oklahoma. In the Anadarko Deep there are three major mature petroleum source horizons: Woodford, Springer-Morrow, and Middle-Upper Pennsylvanian marine shales. In most of the area surveyed, the Woodford is post mature. However, the Springer-Morrow and Middle-Upper Pennsylvanian horizons are currently in the oil and/or thermal gas-generating windows.

Surface gamma-ray surveys were run over 1708 mi in T8-9N, R13-19W to see if there were areas of discrete detectable microseep alteration (anomalies) or whether the entire generating area would be without anomalous contrast. Data were analyzed and anomalies were noted. The anomalies were then plotted against the position of major structural elements and drilling results.

Discrete areas of anomalies were noted, many coincident with established production. More importantly, large areas were seen to be without anomalies. It is most probable that the detectable microseeps at the surface are associated with gathered concentrations of hydrocarbons at depth since the entire area was not found to be anomalous.

AAPG Search and Discovery Article #91008©1991 AAPG Mid-Continent Section Meeting, Kansas Geological Society, Wichita Kansas, September 22-24, 1991 (2009)