Abstract: Integrated Basin Chemical Modelling Redefines the Geothermal Evolution of the Arkoma Basin, Oklahoma, USA

Sara S. Foland, I. D. Meshri, S. L. Bolton, J. M. Walker, K. A. Hegarty

Amoco utilized a variety of exploration technologies to become the economic success leader (EPs > 65%) in the thrusted Pennsylvanian Spiro sandstone play of the Arkoma basin, Oklahoma. It was found early in exploitation analysis that conventional thermal-history methodologies gave conflicting results about the overall geothermal evolution of the basin. Within the thrusted terrain, vitrinite reflectance and bottom-hole temperature data give abnormally low paleo-temperatures. Apatite fission track analysis was unusable for sub-surface samples due to extremely high paleo-temperatures (>110°C at 450m until 50Mya).

Integrated basin Chemical Modelling (IBCM) was used to determine timing of critical events (thrusting, timing of maximum paleo-temperature, generation, expulsion and diagenetic evolution). Preliminary modelling results indicate that maximum temperature post-dates thrusting of the Ouachitas - eliminating the necessity to palinspastically restore individual thrust sheets to determine spatial relationships of traps to migration pathways. Complex hydrologic flow is concentrated within the porous Spiro reservoir section and along thrust planes. IBCM modelling indicates the critical flow direction reverses several times during basin evolution.

The Arkoma basin is divided into two distinct thermal provinces, each experiencing a separate, complex thermal history. Fission track analysis of surface samples indicates two periods of regional cooling - Late Paleozoic and late Cretaceous to Early Tertiary. Timing of these cooling events correlates to flow reversals indicated from IBCM modelling. Hydrologic flow reversals indicate multiple periods of migration/charge and the possibility of subtle stratigraphic traps formed from diagenetic changes within the prospective reservoir intervals.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France