ABSTRACT: 2-D Seismic Revolutionizes Structural Model of Cordona Lake (Devonian) Unit, Crane County, Texas

T. W. Branton, D. J. Christiansen, F. R. Scheubel

Since its discovery in 1949, Cordona Lake (Devonian) Unit, located in Crane County, Texas, has produced 18 million bbl of oil under primary, secondary, and tertiary recovery programs. The field produces from a complexly faulted subunconformity truncation trap where Devonian tripolitic chert subcrops basal Permian shales and tight carbonates. A field wide CO₂ project, implemented in 1985, provided new well control that enabled modest refinements in the geologic reservoir model. Recent acquisition of a two-dimensional seismic survey has significantly improved the structural interpretation of the field and has altered the model from a fairly simple horst-graben feature with three major faults to a fault complex possessing over 21 isolated fault segments. Because m ny of the faults possess relatively small displacements (±50 ft) and the subsurface mapping was hindered by problematic correlations using mostly partial penetrations, the new interpretation would have been impossible without the seismic data. The improved structural reservoir model resulting from the integration of seismic and well log control has yielded new development drilling opportunities. Programs are underway to capture oil previously bypassed due to flooding along restricted or no-flow boundaries or trapped in isolated fault segments.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990