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为防止水合物开采引起的地质灾害,采用有限元方法,对abaqus有限元软件进行二次开发,模拟水合物开采过程中的水、热、力三场耦问题,重点分析水合物开采过程中地层应力场和位移场变化规律.结果表明:降压与加热法联合开采水合物时,降低井口压力可以显著提高水合物的分解速率;水合物分解区附近地层孔压明显降低,土体有效应力增加.海床表面会产生较大的沉降和水平位移,并随水合物分解距离的增大而线性增加,当最大分解范围为30 m时,海床表面最大沉降达5 m,最大水平位移达1.6 m.该研究结果为水合物开采时地层及开采平台稳定性的安全评估提供理论指导.
In order to prevent geological disasters caused by hydrate mining, finite element method was used to develop secondary abaqus finite element software to simulate the coupling problems of water, heat and force during the process of hydrate mining. The strata during the process of hydrate mining were analyzed emphatically Stress field and displacement field.The results show that reducing the wellhead pressure can significantly increase the rate of hydrate decomposition when the hydrate is depressurized by combination of heating and pressure reduction.The pore pressure in the vicinity of the hydrate decomposition zone obviously decreases and the effective stress of the soil increases . The seabed surface will have larger subsidence and horizontal displacement and increase linearly with the hydrate dissociation distance increasing. When the maximum decomposition area is 30 m, the maximum subsidence of the seabed surface reaches 5 m and the maximum horizontal displacement reaches 1.6 m. The results of this study provide theoretical guidance for the safety assessment of the stability of formation and mining platform when hydrate is mined.