Petrophysical Characterization of the Eagle Ford Shale in South Texas

Abstract

Abstract The Eagle Ford shale play is an emerging shale play that extends from the Mexican border in south Texas all the way to the East Texas Basin. Developing the play into an economically viable venture encompasses numerous challenges to include: The shale production characteristics vary across the play. The shale is producing dry gas in some areas and wet gas or oil in others. Some regions are naturally fractured, while others are not. The play must be hydraulically fractured to be economically productive; however, what completion techniques have been successful in one well will not necessarily work in another, even in the same field. Thus, it is critical to consider the local-area reservoir characteristics when trying to complete each well. This paper focuses primarily on understanding the reservoir by integrating various data-acquisition and reservoir-characterization techniques (i.e., mudlogs, basic openhole logs, and advanced logs, such as Dipole sonic, geochemical, NMR (magnetic resonance-imaging log), and core analysis) to determine the shale's petrophysical characteristics and to thus build a locally validated petrophysical model (shale log) that can be applied to future wells with reduced data-acquisition programs to grade the reservoir. The model is used to ascertain the surrounding lithology and clay typing in addition to the hydrocarbon resource potential of the well. Furthermore, this tool can be used to answer completion questions, such as where the organic-rich zones are located, where to perforate, what the geomechanical issues are, how "fracable" the rock is, and how plastic the rock is.