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Collaborating Authors
Results
Effects of Carbon Dioxide Injection in Reactive Carbonates: Computational Rock Physics Basis for Time-Lapse Monitoring
Nur, Amos (1 The Stanford Rock Physics Program, Stanford University) | Vanorio, Tiziana (1 The Stanford Rock Physics Program, Stanford University) | Diaz, Elizabeth (2 Ingrain Inc., Houston, Texas, USA)
Abstract Carbon dioxide injection into natural reservoirs has been used for enhanced oil recovery as well as, more recently, for geologic sequestration. In both technological applications, of major interest is remote sensing of the progress of the injected carbon dioxide through the subsurface as well as its effects on the physical characteristics of the rock, including the elastic, storage, and transport properties. Whereas it may be safe to assume that the presence of carbon dioxide does not alter the mineral matrix in most clastic reservoirs, the situation is very different in carbonates where such alteration may occur in real time, in a matter of hours, days and, certainly, months. Physical laboratory experiments have confirmed that the carbon dioxide interacts with formation water and, eventually, with the mineral matrix (Vanorio, T. et all, 2008). These chemical processes alter the pore space geometry in carbonates and can even create such flow conduits as relatively large wormholes. This pore-space and matrix alterations can definitely affect the elastic properties of carbonate rock, which are crucial in interpreting the 4D time-lapse seismic data for pore-fluid content in space and time. Because of the changes occurring in the mineral matrix during carbon dioxide injection, traditional fluid-substitution techniques often do not work in such reactive rock and, hence, can be misleading during seismic data interpretation.
- Asia > Middle East > Saudi Arabia (0.30)
- North America > United States > Texas (0.29)
- Geology > Geological Subdiscipline > Geomechanics (0.92)
- Geology > Mineral (0.66)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.36)
- Geophysics > Time-Lapse Surveying > Time-Lapse Seismic Surveying (1.00)
- Geophysics > Seismic Surveying (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management (1.00)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (0.95)
Abstract This paper springs from a series of laboratory experiments and high-resolution imaging techniques assessing the changes in microstructure, transport, and seismic properties of brine-saturated sandstones and carbonates when injected with CO2. Results show that the injection of CO2 into a brine-rock system induces chemo-mechanical mechanisms, which permanently change the rock frame. The injection of CO2 into brine-saturated-sandstones induces salt precipitation primarily at grain contacts and/or within small pore throats. Salt precipitation decreases permeability and increases P- and S- wave velocities particularly in sandstones characterized by porosity lower than 10%. On the other hand, the injection of CO2-rich brine into carbonates induces dissolution of the microcrystalline matrix (i.e., micrite) leading to porosity enhancement. Dissolution counteracts and overwhelms a pressure-dependent, chemo-mechanical creeping of the rock leading to compaction. The overall result is the decrease of the elastic moduli of the dry rock frame. These findings demonstrate that monitoring the time-lapse seismic response of chemically stimulated systems is far from being a pure fluid-substitution problem.
- North America > United States > Kansas (0.30)
- North America > United States > Texas (0.29)
- Asia > Middle East > Saudi Arabia (0.29)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.78)
- Geology > Geological Subdiscipline (0.73)
- Geology > Mineral (0.70)
- Geophysics > Time-Lapse Surveying > Time-Lapse Seismic Surveying (1.00)
- Geophysics > Seismic Surveying (1.00)
- North America > United States > Texas > Frio Formation (0.99)
- North America > United States > Kansas > Hall-Gurney Field (0.99)
- Europe > United Kingdom > Atlantic Margin > West of Shetland > Faroe-Shetland Basin > Judd Basin > Block 204/25 > Greater Schiehallion Field > Schiehallion Field (0.99)
- Europe > United Kingdom > Atlantic Margin > West of Shetland > Faroe-Shetland Basin > Judd Basin > Block 204/20 > Greater Schiehallion Field > Schiehallion Field (0.99)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Seismic (four dimensional) monitoring (1.00)