Diagenetic settings at Pirineo block, Sabinas Basin, Mexico: Interaction fluid-rock-hydrocarbon

The Pirineo Block, in the Sabinas Basin, has source rocks formations with organic matter type II and III, and thermal maturity up to 2.5 %Rr to depth (“La Casita” Formation). The organic petrography application, fluid inclusions, and SEM samples of lithological column of the Pirineo Block, proved the influence into the rocks of TSR reactions, causing the improvement or destruction of the petrophysical properties by sulfates and carbonates precipitation, dolomitization and development of stylolites. %Rr and δ13C data fo CH4, determine the oil window for the Jurassic, and gas window for the Cretaceous, in the organic matter studied. δ13C2 - δ13C3 versus C2/C3ratio indicates that the studied gas is mainly product of the secondary cracking of oil and gas. Evidences of TSR reactions found in the Pirineo Block, partially explain the occurrence of H2S and CO2 in the area