Characterizing a Prolific "Liquids Rich" Shale Play: An Integrated Eagle Ford Case Study
Barzola, Gervasio1 and Clarke, Paul R.
The Eagle Ford shale resource play provides a world class natural laboratory for appraisal and exploitation best practices within an unconventional hydrocarbon system. Over a period of approximately four years, our project has evolved from (1) a pilot program where we acquired logs and core data from a handful of strategic wells to help generate resource estimates and regional play maps, to (2) appraisal drilling where several tens of wells helped delineate production patterns and refined thermal maturity trends, and more recently (3) full field development, including down-spacing and multi-well pad drilling. Each stage of this project has presented new challenges, insights and unexpected learning’s about the formation, our ability to stimulate and produce from it, and the value of information we obtained along the way. Here, we share our interpretations and key project performance metrics that may be employed in other basins at the early stages of prospecting or appraisal.
Our early observations and conjecture surrounding well performance have been solidified into proven technical concepts, where sweet-spots have been delineated and key performance drivers identified. It has become evident that well productivity is primarily controlled by local and regional geologic variability with the interaction of several key (often subtle) parameters. These variables include thermal maturity and reservoir pressure, source richness (TOC), brittleness (clay volume), matrix porosity and natural fracture intensity, all of which, to a greater or lesser extent, influence reservoir deliverability and produced fluid properties. A comprehensive knowledge of these parameters and the acquisition of 3D seismic data early in the project were essential for successful planning and execution. Similarly important considerations related to drilling, completion and production procedures have been highlighted that play a secondary role in shaping well performance. These considerations include geo-steering, lateral length, stage design, proppant (type & volume) and choke management. Surveillance initiatives have proved invaluable for understanding completion effectiveness and include micro-seismic monitoring, production logging, radioactive & chemical tracer applications. Holding our completion design constant during the appraisal phase enabled the underlying formation response to be observed, providing a normalized data-set for reserve estimates and benchmarking purposes.
AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013