Paleotectonic control of reservoir facies
Abstract
The basement structural fabric of the Paradox basin affected sedimentary facies throughout Phanerozoic time. Continental-scale basement wrench-fault zones were rejuvenated repeatedly throughout the Paleozoic. The Paradox pull-apart evaporite basin was formed along the northwest-southeast-trending Paradox-Wichita lineament in Middle Pennsylvanian time, facilitated by basement faults of the northeast-southwest-trending Colorado lineament. Structurally controlled shoaling conditions, formed by reactivation of basement faults, fostered marine sandstone reservoirs in Late Devonian time, crinoidal buildups in the Early Mississippian, and phylloid-algae mounds in Middle Pennsylvanian time. Apparently similar basement wrench-fault zones are present in Kansas. The midcontinent rift system is a north-northeast-south-southwest-trending fault zone that was reactivated during the Paleozoic. Northwest-southeast-trending faults along the Central Kansas-Bourbon arch complex appear to have offset structures of the midcontinent rift. Both trends are interpreted to be continental-scale conjugate wrench-fault zones with sinistral displacement along the midcontinent rift and dextral displacement along the Central Kansas-Bourbon arch complex. Stratigraphic relationships suggest repeated reactivation before Pennsylvanian uplift and erosion along the major structures. In both regions major structural lineaments are associated with smaller-scale fault patterns. Reactivation of these structures through time created paleotectonic trapping conditions at several stratigraphic intervals. Evidence is accumulating in Kansas that tectonically controlled paleotopography and paleobathymetry are major predictable factors in reservoir localization. Recognition of reactivated basement structural fabrics can provide* significant constraints on reservoir characterization and modeling.
