Dynamic Reservoir Characterization: Application of Time-Lapse (4-D), Multicomponent Seismic to a CO₂ EOR Project, Vacuum Field, New Mexico

S. L. Roche¹, T. L. Davis², R. D. Benson², and L. Duranti^2
1Output Exploration, LLC
²Colorado School of Mines

A time-lapse (4-D), multicomponent (9-C), seismic data survey was acquired, processed and interpreted in conjunction with a CO₂ Enhanced Oil Recovery (EOR) project at Vacuum Field, New Mexico, USA. The CO₂ injection program induced bulk rock property variations due to fluid saturation and pore pressure changes associated with reservoir production processes. Seismic monitoring utilized four separate 9-C seismic surveys to form a dynamic reservoir characterization of the San Andres reservoir in the study area.

Interpretation of the P-wave and S-wave data volumes, and integration with geological and reservoir engineering data, demonstrate that changes in bulk rock properties associated with the CO₂ injection program could be detected using multicomponent surface seismic data. The primary seismic attribute used to detect the 4-D response was variations in shear wave anisotropy.

Acquisition of the time-lapse (4-D), multicomponent data included generating both P-wave and S-wave energy at each source location using vibrator source units. Each receiver location recorded three components of the seismic wavefield resulting in a full 9-C seismic survey over the project area. Data acquisition of the surface seismic data was augmented with the simultaneous recording of a single, 3-C geophone, positioned in a wellbore centrally located in the survey area at a depth of 1000 m.

A data processing methodology for time-lapse, multicomponent, seismic survey was developed and applied to the P-wave and S-wave data volumes. Significant features of the data processing method are application of surface consistent processes, windowed crosscorrelation of common-trace pairs between the initial and repeat surveys with subsequent decomposition to source and receiver components, and the use of information from the downhole 3-C geophone to constrain P-wave and S-wave data processing.

AAPG Search and Discovery Article #90905©2001 AAPG Southwest Section Meeting, Dallas, Texas