Three-Dimensional Seismic Evaluation of Reservoir Continuity and Four-Dimensional Seismic Monitoring of an EOR Process

Robert J. Greaves, Joseph R. Davis

The technology of three-dimensional reflection seismology has developed to the point where detailed mapping of some reservoir characteristics can be done in manner useful to field development. Two examples of the analysis of high-resolution seismic data for reservoir studies are presented here.

In the first example, the reflection trace amplitude and the calculated seismic attributes of a three-dimensional survey delineate a discontinuous section of reservoir sand and effectively map sand thickness. When local structure is statically removed from the seismic data, time slices through the three-dimensional data volume are interpreted as horizon slices. By correlation of subsurface well information with seismic character, variations in seismic attributes on the horizon slices are interpreted as maps of lateral changes in reservoir parameters.

The second example shows the results obtained using three-dimensional seismic data to monitor the progress of an in-situ fireflood test. Three sets of three-dimensional seismic data were recorded in an identical manner over the test area during a 1-year period. Taken as a whole, the seismic data have a fourth dimension, calendar time. By comparison and direct integration of the data sets, it is possible to map the propagation of the fireflood in the reservoir over time and calculate a net burn thickness map from seismic amplitudes calibrated with post-burn core information. These examples are from small reservoir tests related to the EOR pilots, but as the results imply, the same combinations of three-dimensional seismic and subsurface will control can be applied to large-scale field evelopment.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.