Li, L.; Li, D.; Ma, J.; Wang, D., and Tan, M., 2020. A new method for calculating the moduli of mixed minerals under abnormal pressure applying to the marine reservoir. In: Yang, Y.; Mi, C.; Zhao, L., and Lam, S. (eds.), Global Topics and New Trends in Coastal Research: Port, Coastal and Ocean Engineering. Journal of Coastal Research, Special Issue No. 103, pp. 339–345. Coconut Creek (Florida), ISSN 0749-0208.

Abnormal fluid pressure commonly exists in oil and gas-bearing basins. Abnormally high pressure often coexists with undercompaction, whereas abnormally low pressure is often related to rock porosity rebound. The Voigt-Reuss-Hill (V-R-H) equation, which is the arithmetic mean of the Voigt upper bound and the Reuss lower bound, is often used to calculate the bulk and shear moduli of mixed minerals. In this study, it is considered that the moduli of mixed minerals are closer to the Reuss lower bound in abnormal high-pressure reservoirs and the Voigt upper bound in abnormal low-pressure reservoirs. Hence, a new equation is proposed for calculating the moduli of mixed minerals. Then, the Digby model and the Gassmann equation are used to predict shear-wave (S-wave) velocities, which are subsequently compared with the measured results. The results show that the errors in S-wave velocities predicted by the proposed method are lower than 6%.