Diagenesis Of The Eagle Ford Formation And Its Thermal Markers As A Producer Unconventional Gas

There are several organic matter rich shale geologic formations in Mexico that could be considered non-conventional potential oil reservoirs; one of those formations is the Eagle Ford Formation (Late Cenomanian - Turonian), aim of this strudy The Eagle Ford Formation is located within the Sabinas paleobasin and along the Burns-Peyote paleoplatform in the Coahuila State. This formation has been previously described as a transgression system deposited in a shallow marine environment with a total organic carbon between 0.5 to 8% with type II organic matter For these masons it could he considered a potential source for non-conventional hydrocarbons Therefore, it is considered that a reservoir of shale gas must have certain requirements such as: 1) high total organic carbon (>. 2% of COT), 2) presence of types II and III kerogen, 3) vitrinite reflectance values greater than 1.2% Ro (0.7% for shale oil). 4) thickness greater than 30 m and large extension, 5) fracturability (<40% days or absence of expandable clays) or the presence of a microcracking system, 6) overpressure, 7) adequate depth, 8) heterogeneity, and others A systematic sampling was carried on outcrops of Coahuila State with the goal to determine the thermal maturity degree of the Eagle Ford Formation using a detailed stratigraphic analysis of three columns (CSI, CSII and CSV) and micm-thermometric of fluid inclusions. Ow results indicate that the Eagle Ford Formation is a sedimentary sequence rich in organic matter, locally composed qf carbonaceous carbonate shalt in laminar stratification alternating with shaly limestone (mudstone-wackestone) and clastic o bioclastic limestone (packstone-grainstone). Regarding the diagenetic alteration, primary porosity is affected by compaction and cementation processes However, it was also observed a secondary micro porosity development due to neomorphism. dolomitization, fracturing and stylolitization processes. Measured homogenization temperatures (PO in fluid inclusions are between 65 degrees C and 125 degrees C, reaching the temperature window to generate oil and humid gas. The thermal evolution through its facies changes in the basin is not homogeneous Our results indicate that the Eagle Ford Formation is a sedimentary sequence sick in organic matter, knotty composed of carbonaceous carbonate shale in laminar stratification alternating with shaly limestone (mud-stone-wackestone) and clastic o bioclastic limestone (packstone-grainstone).