Geomechanical Characterization of CO2 Storage Reservoirs on the Rock Springs Uplift, WY
Author | : Hua Yu |
Publisher | : |
Total Pages | : 143 |
Release | : 2018 |
Genre | : Carbon dioxide |
ISBN | : 9780438433632 |
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Carbon sequestration in deep geological formations has been considered as an important and practical solution to significantly reduce the CO2 emission. CO2 injection into reservoirs may lead to mechanical, chemical, and hydrological effects on the geological formations. This Ph.D. research primarily focuses on quantifying and analyzing geomechanical properties and the effect of CO2 on geomechanical properties of reservoir rocks. The research includes: 1) select and prepare rock samples (Weber Sandstone) from Rock Springs Uplift, Wyoming; 2) design and conduct geomechanical experiments; 3) improve the estimations of geomechanical properties of rocks; 4) develop the analytical model describing the nonlinear rock failure behavior; 5) investigate the effect of compliant pores on reservoir rocks under different stress states; 6) quantify and analyze the changes in geomechanical properties of reservoir rocks due to CO2. Major conclusions drawn from this research were summarized. First, a new method proposed for estimating elastic constants and crack propagation stress thresholds significantly eliminates bias due to both user-defined data interval and poor data resolution on the stress-strain data analysis procedures. Second, a generalized power-law failure criterion was derived in terms of the rock strength properties and validated through published test data for different rock types. Third, the nonlinear pore pressure-volumetric strain relationship at low confining pressure changes to a linear behavior at high confining pressure. Fourth, the unstable crack growth region governed by the initial compliant porosity is independent of the differential pressure. Fifth, the effect of CO2 on geomechanical properties of Weber Sandstone in the linear elastic, nonlinear plastic, and post-failure regime is limited. However, a consistent change in Mohr failure coefficients due to CO2 was observed.