Cockrell School of Engineering
The University of Texas at Austin


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Graduate Seminar - Dr. Luis F. Ayala


Monday, May 02, 2016


03:00pm - 04:00pm


CPE 2.204


Speaker:  Dr. Luis F. Ayala – Professor, Department of Energy and Mineral Engineering, Pennsylvania State University

Seminar Title:  “Analytical Studies in Natural Gas Reservoir Performance, Forecasting, and Reserve Prediction: New Models”


In this work, we discuss new-generation analytical decline equations for the analysis of dry and liquid-rich gas wells producing at a variety of conditions. We first show that, for volumetric, single-phase, gas reservoirs produced at constant bottomhole pressure, the decline exponent, b, used in the well-known Arps’ hyperbolic model can be calculated solely on the basis of fluid properties and the prevailing bottomhole specification—regardless of reservoir properties and before collecting any rate-time data. We then demonstrate that a rigorous derivation of rate-time behavior for gas well performance, based on fundamental physical principles applicable to boundary-dominated flow, leads to rescaled exponential models. This density-based methodology does not employ any type of pseudo-time calculations for OGIP straight-line calculations. We also present a semi-analytical methodology based on the similarity method that analytically corroborates that constant GOR behavior is fully predictable for unconventional multiphase wells exhibiting linear flow. The methodology proves that constant volume depletion (CVD) test data provide very poor estimations of saturation-pressure path for all cases considered—a source of So-p data commonly used in two-phase pseudopressure calculations. A number of field and numerical case studies are presented to showcase the capabilities of the proposed approaches.


Luis F. Ayala is Professor of Petroleum and Natural Gas Engineering, Associate Head for Graduate Education, and holder of the William A. Fustos Family Professorship in the John and Willie Leone Family Department of Energy and Mineral Engineering at the Pennsylvania State University. His research activities focus on the areas of natural-gas engineering, unconventional-reservoir analysis, and numerical modeling. Ayala holds PhD and MS degrees in petroleum and natural gas engineering from the Pennsylvania State University and two engineering degrees with summa cum laude honors, one in chemical engineering and another in petroleum engineering, from Universidad de Oriente in Venezuela. He has received the SPE Outstanding Technical Editor Award and the Wilson Award for Outstanding Teaching from Pennsylvania State University. Ayala is the specialty coordinator of the Reservoir Description and Dynamics Committee for the 2016 SPE Annual Technical Conference and Exhibition (ATCE) in Dubai, and has served as a member of the SPE Reservoir Description and Dynamics Advisory Committee, as member and chair of the Reservoir Engineering Subcommittee in past ATCEs, as associate editor for SPE Reservoir Evaluation & Engineering, and as editor-in-chief of SPE’s The Way Ahead.