SILICA GELS FOR ENHANCING OIL AND GAS CARBONATE RESERVOIRS PERFORMANCE AND CO2 STORAGE

Reservoir heterogeneity (structural or lithological) severely affects the flow of gas, oil, and water in the reservoir and thus affects production strategies, reservoir management, and ultimately oil recovery. Reservoir heterogeneity is the single most important factor for low oil recovery and early excess water production. To maintain reservoir pressure, these reservoirs were developed by water- or CO2- flooding. Several of them have been hydraulically-fractured, intentionally or unintentionally. Reservoirs with induced fractures or high-permeability pathways are quite common in the mature oilfields and gel treatment is one of the most promising remedy to correct the reservoir permeability. Gel treatments are cost-effective methods to improve sweep efficiency in reservoirs and reduce excess water production during oil and gas production. However, these diverters are often organic polymers that raise environmental concerns. Silicas, however, are inorganic and environmentally friendly as opposite to organic gels often used in oil/gas industry. There should be, therefore, fewer environmental restrictions and permitting requirements. Silica gelation can be triggered externally, for example by mixing with salt solutions, changing the pH, changing the colloid surface area, or increasing temperature. We will present several silica gel deployment strategies for enhanced oil and gas recovery and reservoir conformance as well as supercritical carbon dioxide storage in carbonate reservoirs. We have integrated hundreds of experimental data for time gelation conducted at LLNL into StoTran which is a numerical framework for simulating transport phenomena in porous and fractured media. Using StoTran explored the space of key parameters for successful silica gel deployment for specific reservoir management objectives whether reservoir conformance, enhanced oil recovery or CO2 storage.

This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.