Building the 3-D Jigsaw Puzzle: Applications of Sequence Stratigraphy to 3-D Reservoir Characterization, Permian Basin

Abstract

Reservoir characterization involves the quantification, integration, reduction, and analysis of geological, petrophysical, seismic, and engineering data. This is no small task. A principal goal of reservoir characterization is to derive a spatial understanding of interwell heterogeneity. Traditionally, geologic attempts to characterize interwell heterogeneity have been done using hand-drawn or computer-generated two-dimensional (2-D) maps and cross sections. Results can be improved dramatically using three-dimensional (3-D) interpretation and analysis techniques. Three-dimensional reservoir characterization requires the same input data used in 2-D approaches, and the cost is equal to, and commonly lower than, traditional 2-D methods. The product of 3-D reservoir characterization is a 3-D reservoir model. The language used to communicate the results of a 3-D reservoir model is visualization; i.e., visual images of numerical data. All of the available log and core data in a model area are incorporated in a 3-D model, but the data are depicted as colored cells rather than as log traces. The integrity of the 3-D reservoir model is largely a function of the stratigraphic framework. Interpreting the correct stratigraphic framework for a subsurface reservoir is the most difficult and creative part of the 3-D modeling process. Sequence and seismic str tigraphic interpretation provide the best stratigraphic framework for 3-D reservoir modeling. The purpose of this paper is to discuss the process of 3-D deterministic reservoir modeling and to illustrate the advantages of using a sequence stratigraphic framework in 3-D modeling. Mixed carbonate and siliciclastic sediment outcrop and subsurface examples from the Permian basin of west Texas and New Mexico will be used as examples, but the concepts and techniques can be applied to reservoirs of any age. Three-dimensional reservoir modeling results in an improved geologic interpretation; provides a means of integrating geological, petrophysical, geophysical, and engineering data; and allows for immediate model updates as new data are acquired. As a result of 3-D reservoir characterization, reservoir management decisions, data quality control, volumetric calculations, numerical sim lation input, and communication between disciplines are improved.