A Model for the Discovery of a Hydrocarbon Bearing Listric Fault System
D. P. Stapp
Independent Consulting Geologist for Black Oil Company, Inc. Addison, TX
The occurrence of hydrocarbon-trapping listric fault systems has been known in the latter history of oil and gas exploration. The fault mechanisms associated with these types of structural occurrences are not simple expressions of linear/hinge type movements. The afterreaction of a major structural component is not necessarily a rare situation and has been well recognized in the exploitations of hydrocarbons. Such an example of a listric fault system in a highly complex basinal area has been identified in the Marietta-Ardmore Basin of Southern Oklahoma and North Texas. We conclude that the simultaneous action of the generation of the Sherman Anticline and a listric fault system in Grayson County, Texas has generated a small but very prolific structural/stratigraphic accumulation of hydrocarbons. The asymmetrical Sherman anticline lies about four miles southwest of the Oauchita thrust front, with its axis more or less parallel to the thrust front, suggesting that the final or thrusting movements may have influenced its structural development. The movement of this feature probably induced the generation of a listric fault with rollover folds which are very important structural traps in the John Hudgins lease of Grayson County, Texas. Being located toward the foreland portion of the basin, these folds are probably within a passive margin of the basin. The gravitational action thus formed longitudinal folds as a result of movement on the listric fault system. Thus the accumulation of hydrocarbons in the clastic sequences of lower Pennsylvanian age (Baker and Davis) formations has occurred in these rollover folds, especially since the Baker is sourced by the Atoka shales just below and the Davis is recognized by most geologists familiar with this basin as petroliferous. The identification of this listric fault system was isolated from a 3-D seismic program coupled with a regional geologic and geophysical foreknowledge of the character of the basin. Characterization of this fault system in such a structural trap has provided the basis for the revelation of a new oil and gas field, and the resulting optimization of well placement for optimum reservoir drainage.
AAPG Search and Discovery Article #90905©2001 AAPG Southwest Section Meeting, Dallas, Texas