The objectives of the project are to:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA
Anadarko Petroleum Corporation, Oklahoma City, OK
Unocal Corporation (now part of Chevron Corp.), El Segundo, CA
University of Texas, Austin, TX
Several current and recent NGOTP projects have focused on reservoir fluid and lithology prediction from single boreholes, between boreholes, and from surface measurements, including:
These projects have developed state-of-the-art data acquisition and modeling techniques for seismic and EM data.
The Integrated Reservoir Monitoring Using Seismic and Crosswell Electromagnetics project has demonstrated the added spatial resolution that can be gained in saturation prediction by combining seismic and EM data in the interpretation process. Work to date on the combined use of seismic and EM has centered on an iterative, interpreter-driven process of using results from one technique to guide and constrain the interpretation of the other. The next logical step is to develop a rigorous formal linkage between seismic and EM imaging through the mathematics of inversion.
This project has developed a method for combining seismic and EM measurements to predict changes in water saturation, pressure, and carbon dioxide gas/oil ratio in a reservoir undergoing CO2 flooding. The algorithms and methodology are applicable to any oil and gas applications with multiphase-fluid flow.
Crosswell seismic and EM data sets taken before and during CO2 flooding of an oil reservoir were inverted to produce crosswell images of the change in compressional velocity, shear velocity, and electrical conductivity during a CO2 injection pilot study. A rock properties model was developed using measured log porosity, fluid saturations, pressure, temperature, bulk density, sonic velocity, and electrical conductivity. The parameters of the rock properties model are found by an L1-norm simplex minimization of predicted and observed differences in compressional velocity and density. A separate minimization, using Archie’s law, provides parameters for modeling the relationships among water saturation, porosity, and electrical conductivity. The rock-properties model is used to generate relationships between changes in geophysical parameters and changes in reservoir parameters. Electrical conductivity changes are directly mapped to changes in water saturation; estimated changes in water saturation are used, along with the observed changes in shear wave velocity to predict changes in reservoir pressure.
The estimation of the spatial extent and amount of CO2 relies on first removing the effects of the water saturation and pressure changes from the observed compressional velocity changes, producing a residual compressional velocity change. This velocity change is then interpreted in terms of increases in the CO2 /oil ratio. Resulting images of the CO2/oil ratio show CO2-rich zones that are well correlated to the location of injection perforations, with the size of these zones also correlating to the amount of injected CO2. The images produced by this process are better correlated to the location and amount of injected CO2 than are any of the individual images of change in geophysical parameters.
The algorithms developed have been demonstrated to be superior at predicting fluid saturation within a reservoir compared with prior technology. The research and publications from this project have led to the successful developments of the follow-on Natural Gas and Oil Technology Partnership (NGOTP) project, Joint Geophysical Imaging, which has led to over $1,000,000 in direct industry funding for joint seismic and electromagnetic inversion research at LBNL.
Project researchers have:
The original project concluded at the end of 2003; additional funding has continued the research. The result has shown that seismic data could provide information on rock physics parameters
Lawrence Berkeley National Laboratory (LBNL) with the University of Texas, in a DOE Project, has developed state-of-the-art data acquisition and modeling techniques for integration of seismic and Electro-Magnetic (EM) data. The Integrated Reservoir characterization using seismic and cross-well EM data has demonstrated the added resolution in hydrocarbon saturation prediction. The project also involves the development of algorithms and computer codes for the interpretation of borehole seismic and EM measurements. The successful integration of borehole sonic and EM measurements considerably improves the current state-of-the-art technology to detect and assess the hydrocarbon potential of reservoir flow units undetectable with conventional seismic methods. Researchers will continue to validate the results with field data.
This project was funded through DOE’s NGOTP program. The project is a joint contract with the University of Texas at Austin, DE-FC26-04NT15507.
The original project concluded at the end of 2003; additional funding continued the research.
Hoversten, G.M., Milligan, P., Byun, J., Washbourne, J., Knauer, L.C., Harness P., 2003, Crosswell electromagnetic and seismic imaging: An examination of coincident surveys at a steamflood project. Geophysics 69, 406- 414 .
Hoversten, G.M., Gritto, R., Washbourne, J., Daley, T.M., 2003, Pressure and Fluid Saturation Prediction in a Multicomponent Reservoir, using Combined Seismic and Electromagnetic Imaging: Geophysics, 68, 1580-1591.
Chen, J. and Hoversten, M., 2003, Joint stochastic inversion of geophysical data for reservoir parameter estimation, 73rd Ann. Internat. Mtg., Society of Exploration Geophysicists, 726-729.
Hoversten, G.M., Gritto, R., Daily, T., Washbourne, J., 2002, Fluid saturation and pressure prediction in a multicomponent reservoir by combined seismic and electromagnetic imaging, SEG Expanded Abstracts, 1770-1773.
Hoversten, G.M., Gritto, R., Kirkendal, B., 2001, Crosswell Seismic and Electromagnetic Monitoring of CO2 Enhanced Oil Recovery, SEG Development & Production Forum, Taos, NM.