An Integrated Approach for Reservoir Description Using Seismic, Borehole, and Geologic Data

Abstract

Abstract The contribution that seismic data can make to the structural and stratigraphic model of a reservoir and, in some favourable cases, to delineate fluid contacts is well known. However, lithologic control in reservoir simulation models frequently are limited to information gathered at wells. Any advance in interwell correlation will strengthen the validity of the models. A practical constrained inversion technique is proposed by which a seismic survey can be used to improve the estimates of lithology and porosity in undrilled areas of a reservoir on a scale appropriate for reservoir simulation modeling. The input data for the constrained inversion technique are wide-band synthetic acoustic logs produced by combining borehole logs, seismic and geological data. The basis of the inversion method is to distribute conventionally interpreted borehole estimates of lithology and porosity throughout a field, guided by the existing seismic-geologic interpretation of the field's structure and stratigraphy. Selected petrophysical relationships and constraints are invoked in an iterative inverse procedure to perturb the lithologic and porosity models by the least amount necessary to explain the seismic data. The final result is a highly detailed lithologic and porosity model of the field consistent with all available borehole, geologic and seismic data, suitable for use in field evaluation and for building reservoir simulation models. Also, these detailed estimates may be calibrated with core data to provide useful information about the permeability variation throughout the field. The complete approach is illustrated with a field data example from a prospect where complex reservoirs are present.