Organic richness and source rock potential of the La Peña Formation in the Sabinas and Piedras Negras basins, NE of Mexico

Abstract

This paper investigates the petroleum generation potential of the Lower Cretaceous organic-rich rocks of the La Peña Formation in the Sabinas and Piedras Negras Basin (SB-PNB) of northeastern Mexico. In order to provide insights into the source rock potential of this unit, a total of 25 cutting samples collected from 15 wells at different stratigraphic intervals along the study area were analysed using Rock-Eval Pyrolysis technique. The analytical results revealed that all the analysed samples can be described as hydrogen-poor organic matter with HI <200 mg HC/g TOC. The organic richness indicates a poor to excellent Total Organic Carbon content suggesting that existed different conditions during the deposition and burial of this unit, causing variable organic matter production and preservation. Also, the results revealed a variation in the kerogen types that may be attributed to the relative stratigraphic positions of the selected samples in the wells. With respect to the organic matter thermal maturity, given by the geographical distribution of the Tmax values, the mature and overmature zone (435–508 °C) correspond to the Sabinas basin (SB). Overall, these results show a variability in the organic richness, thermal maturity and petroleum potential of the La Peña Formation, differentiating the values of the TOC content, petroleum potential and HI content for the samples from the Sabinas Basin and Piedras Negras Basin, respectively.