| Popis: |
Water injection increases the percentage of recovery by means of providing pressure support and displacing the oil in the heterogeneous porous medium. In such a displacement process, mobility ratio is important for a more efficient displacement of oil by the injected fluid where mobility ratio can be improved using the fluids involving gelling agents, resulting in increased volumetric sweep. While polymers degrade and break up upon experiencing sudden extreme shear stresses and temperatures, polymer macromolecules are forced to flow into narrow channels and pores, molecular scission processes can take place, thus it is of outmost importance to have a strong understanding of use of right type and amount of viscosity reduction agent. For polymer injection, a comparison of xanthan polymer and synthetic polymer mechanisms was conducted. A commercial full-physics reservoir simulator is coupled with a robust optimization and uncertainty tool to run the model where a simplified gel kinetics is assumed to form a microgel with no redox catalyst. Water injection continues over all 6 layers for 450 days, followed by gel system injection for 150 days, in the bottom 2 layers. Water injection is continued to 4 years. The top four layers have higher horizontal permeabilities, and a high-permeability streak is at the bottom of the reservoir to reduce any helpful effects of gravity. Control and uncertainty variables are set to investigate the sensitivity under this process using the coupled optimization and uncertainty tool. Results demonstrate deep penetration of gel and blocking of the high permeability bottom layers. Sensitivity studies indicate the relative merits of biopolymer, xanthan polymer in terms of viscosity effects vs synthetic PAM in terms of resistance factor vs insitu gelation treatments and their crossflow dependence. Adsorption and retention of polymer and gel are permeability dependent. Considering the fact that there is a significant potential for application of gel solutions in the US and throughout the world, this study illustrates the relative advantages of different treatments in terms of viscosity reduction in the same model in a comparative way outlining the significance of each control and uncertainty variable for better management of reservoirs where displacement efficiency is very critical. |
