Along-strike variation in extension and cross-strike fractures in Stratton field, south Texas: Implications for fractured reservoir description and characterization

Abstract

Summary Stratton Field, a large gas-producing property in south Texas, lies within the Texas Gulf coast and features extensional structures in the Rio Grande embayment. The study area is primarily characterized by north-south trending growth normal faults and associated rollover anticline affecting the Frio and Vicksburg formations. Three-dimensional (3D) seismic structural interpretation from attribute analysis indicates cross-strike fractures and a major transfer fault perpendicular to the regional structural trending that have not been well documented in previous studies. The changes in fault geometry and fracture densities across the transfer zone strongly suggest that the northern segment suffered greater extension and stronger deformation than the southern one. Cross-section restoration indicates the magnitude of extension increases from south to north. Along-strike variations in geometry of rollover anticline and bed curvature suggest that the crossstrike fractures and transfer fault are kinematically linked to the differential movement of adjacent segments. The alongstrike structural variation and cross-strike fractures are typical of oil and gas fields within basins of the Texas Gulf coast. These findings contribute to better characterization of fractured reservoirs and evaluation of reservoir properties and cap rock integrity in extensional settings.