降压开采下深海能源土斜坡分解区的判定及其稳定性分析

深海能源土是指含新型战略性新能源-天然气水合物的海底沉积物。降压开采天然气水合物是一种相对经济、高效的方式，开采中水合物储层分解区域的确定与能源土斜坡稳定性分析是确保天然气水合物安全有效开采的前提之一。本文归纳了水合物降压开采的基本方程，通过自主编写USDFLD子程序，在ABAQUS中实现了降压开采条件下海底斜坡水合物储层分解区域的判断，模拟了水合物饱和度以及相关物性参数的变化情况。结合一实际海底能源土斜坡，完成了降压开采条件下能源土斜坡水合物储层分解区域、有效应力及变形场的计算，并结合有限元强度折减法对深海能源土斜坡降压开采的实际工况进行了数值模拟。结果表明开采前与开采后的安全系数变化不大，单井降压开采对斜坡的稳定性影响不明显。

Study on Decomposition Zone and Stability Analysis of Deep Sea Energy Soil Slope under the Condition of Depressurization

Deep sea energy soil refers to sea bed sediments containing new strategic energy-natural gas hydrate. Depressurization is a relatively economical and efficient way to exploit gas hydrate, the determination of the decomposition zone of hydrate reservoir and the stability analysis of energy soil slope are one of the preconditions to ensure the safe and effective exploitation of gas hydrate. In this paper, the basic equations of hydrate depressurization mining were summarized firstly. The determination of decomposition area of submarine slope hydrate reservoir under the condition of depressurization mining was realized in ABAQUS software by programming the USDFLD subroutine, and the variation of hydrate saturation and related physical property parameters was simulated. Combining with an actual deep sea energy soil slope, the decomposition area, the effective stress and deformation field of the energy soil slope under the condition of depressurization was calculated, and the actual condition of the deep sea energy soil slope was simulated by the finite element strength reduction method. The results show that the safety factor changes little before and after mining, and the effect of single well depressurization mining on slope stability is not obvious.