New insights from a 3D earth model, deepwater Gulf of Mexico

Abstract

A 3D earth model, a geophysical/geologic three-dimensional (3D) model of the earth, is best described in terms of its exploration objective. This means that when its geologic target is established, the model is designed to represent the geologic environment surrounding the prospective target. The areal extent covered can range from regional (i.e., hundreds of OCS blocks) to a detailed nine blocks. At minimum, the earth model is an accumulation of the results of multiple sciences approximating the earth's lithology. At best, through the skilled interpretation of integrating the results of these sciences, it can bring new insight through the refinement of the salt configuration. The 3D earth model described in this article encompasses 144 square miles—16 OCS blocks in the deepwater region of the Gulf of Mexico. The primary objective—i.e., to establish a quantitative interpretation of the structural configuration of the base of an allochthonous salt mass as shown on Figure 1—was achieved through the following steps: Figure 1. Seismic section illustrates the problem of determining the base of an allochthonous salt mass. The deeper reflectors show the possibility of the sedimentary section under the salt, but how far laterally and at what depth does it truncate against the salt are questionable (Seismic section courtesy of Veritas). The geophysical problem that we faced in this project is fairly simple to …