Petrographic and petrophysical characterization of the Eagle Ford Shale in La Salle and Gonzales Counties, Gulf Coast Region, Texas.

摘要

he Eagle Ford Shale is an organic-rich marine carbonate-dominated mudrock located in the Gulf Coast Region, Texas. This mudrock was deposited during the Late Cretaceous and is composed of two main members: the lower and the upper Eagle Ford, which are associated to marine transgression and regression episodes respectively. Petrographic analysis of two cores from wells located in Gonzales (Well ;Pore system was characterized at both well locations by combining water immersion porosimetry (WIP), mercury injection capillary pressure (MICP) and scanning electron microscopy (SEM). Total porosity results indicated that WIP overstates the total porosity when clay content is above 50 wt. %. MICP shows more reliable total porosity values where mineralogy does not apparently affect the experiment final results. Total porosity ranges between 0.32-10.27 percent, where most pore throats diameters fall within the nanopore to micropore size range. Intraparticle pores within the organic matter are dominant in the Eagle Ford, especially in Well ;Hydrocarbon potential was studied by using both the Basic/Bulk-Rock and Institut Francais du Petrole Energies Nouvelles (IFPEN) Shale Play Rock-Eval pyrolysis methods. The IFPEN Shale Play method allows to a better quantification of the hydrocarbons in unconventional plays compared to the Basic/Bulk-Rock method. The average increase in hydrocarbons quantification using the new method is 25.69 percent. The intervals with higher hydrocarbons content are the lower Eagle Ford at Well