ABSTRACT

In eastern Sequoyah County, Oklahoma, natural gas is produced from structural traps developed on anticlines and fault blocks. The structural geology of the surface can be projected into the subsurface and initial estimates of the subsurface orientation of structures can be mapped. Areal surface geologic maps and subsurface structural contour maps were employed in an attempt to delineate these structures.

Gas is produced from several zones in this area. The Cromwell Sandstone (Morrowan) is the most productive reservoir. The Spiro Sandstone (basal Atokan) is also a significant reservoir in this area. Stratigraphic cross-sections, an isolith map of the Cromwell Sandstone, and analysis of typical log responses of these reservoirs were employed in an effort to better understand the facies preserved in this rock unit. Typically gas fields are developed where reservoirs are distributed on anticlines and upthrown fault blocks.