Deep Diagenesis of Cenomanian-Turonian Source Rocks in the Sabinas Basin, Northern Mexico: Implications for Unconventional Hydrocarbon Accumulation

We analyzed the dynamics of interacting fluids within the Upper Cenomanian-Lower Turonian clay-carbonate organic matter rich (source rock) sequence associated with hydrocarbon generation. The diagenetic alterations, authigenic minerals, temperatures of formation, isotopic data (δ13C 0 / 00 and δ18O 0 / 00 ) of the matrix and carbonated cements were examined along with fluorescence of hydrocarbons present. Of the three thermal episodes related to diagenetic cements, one is associated with gas production with temperatures between 99° and 168°C. The isotopic data for δ13C 0 / 00 and δ18O 0 / 00 show calcite production associated with the generation of CO2 derived from organic matter, as well as the interaction of hot fluids, organic acids, and meteoric waters. Due to the increased compaction and deepening of the sequence, these fluids together with light and intermediate hydrocarbons migrated through the dissolution, re-crystallization, and fracture zones, expelling the hotter fluids through the large faults that limit the flow. basin edge. The presence of light and intermediate hydrocarbons in permeable zones indicates that the Eagle Ford and Indidura Formations are also acting as reservoir rock due to the opening of the system. Finally, with the micro-thermometric data of fluid inclusions, a thermal convection model is proposed with the zones with production of wet gas and dry gas within the Sabinas Basin.