Experimental study on evolution behaviors of triaxial-shearing parameters for hydrate-bearing intermediate fine sediment

Abstract

Evolution behaviors of triaxial shearing parameters are very important for geo-technical re- sponse analysis during the process of extracting natural gas from hydrate-bearing reservoirs. In order to explore the effects of hydrate formation/decomposition on triaxial shearing behaviors of intermediate fine sediment, natural beach sand in Qingdao, China, which was sieved from 0.1 to 0.85 mm, was used and a series of triaxial shear tests were carried out in this paper. The principle of critical state was firstly used to explain the mechanism of strain softening and/or hardening failure mode. Moreover, an empirical model was provided for axial-lateral strain and corresponding model parameters calculation. Evolution rules of critical strength parameters were analyzed prominently. The results show that failure mode of sediment is controlled by several parameters, such as effective confining pressure, hydrate saturation, etc. Different axial-lateral strain model coefficients’ effect on strain relationships are different, probing into the physical meaning of each coefficient is essential for further understanding of strain relationships. Complex geo-technical response should be faced with the progress of producing natural gas from hydrate-bearing reservoir, because of sudden change of failure pattern and formation modulus. Further compressive study on critical condition of failure pattern is needed for proposed promising hydrate-bearing reservoirs. Cited as : Li, Y., Liu, C., Liu, L., Sun, J., Liu, H., Meng, Q. Experimental study on evolution behaviors of triaxial-shearing parameters for hydrate-bearing intermediate fine sediment. Advances in Geo-Energy Research, 2018, 2(1): 43-52, doi: 10.26804/ager.2018.01.04