The Integration of Seismic and Well Data for Improved Reservoir Models

ABSTRACT The contribution that seismic data can make to the structural and stratigraphic model of a reservoir is well known, as is its ability to delineate fluid contacts in favorable circumstances. 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 presented 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 acoustic logs estimated from the wide band combination of 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 detailed seismic reflection amplitude data. The final result is a highly resolved 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 technique is illustrated with a field data example from a three dimensional seismic prospect where complex reservoirs are present.