Advanced seismic techonology improves prospect evaluation and reservoir delineation in the mature Macuspana Basin, Mexico

Abstract

An integrated study involving advanced seismic attribute and reservoir characterization tools in Macuspana Basin of Mexico provided an understanding of the structure, reservoir continuity, and quality of three mature reservoirs that optimized new drilling locations for exploration and development and generated a reservoir model for simulation purposes. Conventional and advanced technologies were integrated after a feasibility analysis to generate several attribute cubes over a 3D seismic volume; these included acoustic impedance, amplitude variation with offset (AVO), porosity derived from artificial neural network (ANN) schemes, and spectral decomposition. These attributes, added to the structural and stratigraphic analysis and to a J-function capillary pressure analysis, yielded information on compartmentalization that provided a geologic model to support reservoir delineation and characterization. Cobo, Bitzal, and Guiro fields are in Macuspana Basin, state of Tabasco, southeastern Mexico (Figure 1). The Cobo area, which includes the Cobo, Bitzal, and Guiro fields, is stratigraphically and structurally complex; its complexity is comparable to that of many other gas-producing fields in Macuspana Basin in which the dominant trap mechanisms vary from fault-assisted closures with a stratigraphic component to purely stratigraphic traps. The fields have produced gas for more than 20 years from a series of thin, principally Plio-Pleistocene sands thought to be fluvial-to-deltaic in origin. Cobo fields are cut by many NE-SW striking faults. Some northwest-dipping faults exhibit classic growth fault geometries; some show evidence for reactivation and inversion. This complexity, coupled with older well data, makes analysis using traditional exploration and reservoir characterization tools challenging. Figure 1. Map of Cobo area. Historically in Cobo fields, selection of well locations depended first on structural and stratigraphic analysis using limited 2D seismic; then, when 3D seismic became available, 3D seismic interpretation, detailed amplitude analysis, and AVO schemes were used as the basis for proposing new well sites. Amplitude, AVO, and resistivity measurements …