Clustering/Geostatistical/Evolutionary Approach for 3D Reservoir Characterization and Assisted History Matching in a Complex Carbonate Reservoir
- Dennis Denney (JPT Technology Editor)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- July 2008
- Document Type
- Journal Paper
- 60 - 63
- 2008. Society of Petroleum Engineers
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- 65 since 2007
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This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 113978, "Integrated Clustering/Geostatistical/Evolutionary Strategies Approach for 3D Reservoir Characterization and Assisted History Matching in a Complex Carbonate Reservoir, SACROC Unit, Permian Basin," by R. Gonzalez, SPE, K. Schepers, SPE, and S.R. Reeves, SPE, Advanced Resources International; E. Eslinger, SPE, Eric Geoscience and College of Saint Rose; and T. Back, NuTech Solutions, prepared for the 2008 SPE Improved Oil Recovery Symposium, Tulsa, 19-23 April. The paper has not been peer reviewed.
An integrated methodology combining clustering-analysis techniques, geostatistical methods, and evolutionary-strategy technologies was developed and applied to a study area of the SACROC Unit. Clustering methods were applied to well logs and core data (with high vertical resolution for many wells) to predict porosity, permeability, and rock type. Geostatistics was applied to extend the characterization into the interwell area. Evolutionary strategies were used to refine the characterization to match historical production performance.
Initially, a two-step soft-computing procedure was developed to generate core-scale porosity and permeability profiles at well locations where no core data existed. The approach applied clustering methods, based on maximum-likelihood principles, to well-log and core data for lithology interpretation, reservoir-quality characterization, and prediction of “core” parameter profiles, with high vertical resolution for many wells. This procedure enabled populating any well location with core-scale estimates of porosity and permeability and rock types, facilitating direct application of geostatistical techniques to build 3D reservoir models. Geostatistical methods then were applied to the resulting data set, and 3D spatial models of variability for clusters, porosity, and permeability were used to generate reservoir representations of porosity and permeability for flow-simulation purposes. Finally, a computer-assisted history matching by applying evolutionary-strategy technologies was used to history match the production performance of a selected subregion in the unit.
The SACROC Unit comprises most of the Kelly-Snyder field and part of the Diamond “M” field in Scurry County, Texas. The unit is developed in Pennsylvanian-age reef carbonates of the Cisco and Canyon formations, with productive carbonates in both formations. The productive interval is composed mainly of limestone, although minor amounts of anh-drite, chert, sandstone, and shale can be found locally. Dolostone is rare to nonexistent. The overlying Wolfcamp shale constitutes a natural top and lateral seal. Toward the east and west boundaries, the Cisco/Canyon productive carbonate interval narrows and drops below the regional oil/water contact. Carbonate accumulations present extremely complex geometries and steep sides.
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