The Eagle Ford Formation is a well-known shale gas/oil unconventional reservoir in the United States. The purpose of this study was to evaluate the hydrocarbon potential and thermal maturity of Eagle Ford Formation in northeast Mexico (Coahuila State).
The geochemical characterization was performed using Rock Eval pyrolysis results, vitrinite reflectance data and optical studies of organic matter, on core and cutting samples from wells within the study area. Pemex provided the set of information to evaluate the source rock potential and thermal maturity in order to identify the sweet spots in the area.
A detailed description of two continuous analogous outcrop coring, constrained the variation of organic content along the Eagle Ford Formation. The two cores comprise a complete record of the Eagle Ford Formation with thickness of 47.5 m and 86.8 m, respectively.
Lower Eagle Ford Formation (LEF) presents higher TOC values than the Upper Eagle Ford Formation. Furthermore, the higher TOC values in the LEF are found in the southwest and northwest portions of the study area, which is related to the deep marine facies identified in those regions. In contrast, minor TOC values are recognized in the central portion of the study area, where the outer platform facies have been interpreted for the LEF. Remnant kerogen correspond to Type II/III while Tmax and %Ro values indicate that the Eagle Ford Formation exhibits a thermal maturity ranging from the oil window to the dry gas window showing a maturity trend increasing towards the southeast portion of the study area.
This study confirmed the relevance of the Eagle Ford Formation as an unconventional reservoir in northeastern Mexico, and allowed to identify sweet spots. In addition, the detailed geochemical characterization performed on two continuous analogous outcrop coring provided essential data that allowed to calibrate the unconventional petroleum system modelling of the Eagle Ford Formation in the study area.