This Small Business Innovation Research Phase I project concerns using elastic P-wave and S-wave seismic data simultaneously to obtain time-lapse seismic monitoring images of fluid saturation and pore pressure changes in an oil reservoir. Time-lapse seismic using P-waves alone may not allow discrimination between fluid saturation changes and reservoir pressure changes since such information is contained in the large source-receiver offsets of P-wave seismic data, which can be contaminated by noise and subject to data acquisition aperture limitations. Using S-waves in addition to P-waves in time-lapse analysis can lead to more accurate inversion results, yielding reliable estimates of reservoir saturation and pressure changes. The proposed project will allow customers to avoid costly errors in development and production of economic oil reservoirs and yield higher recovery rates. For this feasibility phase a reservoir model will be constructed, and three-dimensional P- and S-wave synthetic seismic data at two production times will be generated. These time-lapse P- and S-wave data sets will be processed simultaneously and will be cross-equalized and inverted to yield changes in reservoir saturations and pressure. The inverted data will be analyzed to assess the feasibility of the proposed approach on field data. Commercial applications of the technology proffered by Fourth Wave Imaging will include accurate mapping of bypassed oil and monitoring of costly injected fluids. In addition, the firm will be able to better image flow compartmentalization and determine the hydraulic properties of faults and fractures. These applications will allow cheaper and more efficient production of oil reservoirs, guide reservoir management decisions, and help maximize the life of both new and existing fields while minimizing recovery costs. The proposed methods also have commercial applications in monitoring ground water reserves, contaminant plumes and environmental clean-up projects. In medical imaging, use of elastic waves has the potential to yield superior results over acoustic waves alone. Commercial products resulting from this work will consist of time-lapse P- and S-wave seismic data processing, interpretation and analysis tools and methods.
