天然气水合物分解诱发海底滑坡影响因素分析及致灾风险评价  

INFLUENCE FACTORS AND RISK ASSESSMENT FOR SEABED LANDSLIDES INDUCED BY NATURAL GAS HYDRATE DECOMPOSITION

作　　者：唐常锐 徐秀刚[1,2] 孙秉才 姜瑞景 TANG Changrui;XU Xiugang;SUN Bingcai;JIANG Ruijing(College of Marine Geosciences,Ocean University of China,Qingdao 266100,China;Key Lab of Submarine Geosciences and Prospecting Techniques,Ministry of Education,Qingdao 266100,China;China Petroleum Group Safety and Environmental Protection Technology Research Institute Co.Ltd.,Beijing 102206,China)

机构地区：[1]中国海洋大学海洋地球科学学院,青岛266100 [2]中国海洋大学海底科学与探测技术教育部重点实验室,青岛266100 [3]中国石油集团安全环保技术研究院有限公司,北京102206

出　　处：《海洋地质前沿》2021年第5期14-21,共8页Marine Geology Frontiers

基　　金：国家自然科学基金(41204088);直属院所基础科学研究和战略储备技术研究基金“水合物开发甲烷逸散环境影响与诱发典型地质灾害风险评价技术研究”(2019D-5008);海洋石油勘探国家工程实验室开放基金课题(CCL2020RCPS0419RQN)。

摘　　要：天然气水合物主要赋存于低温高压下的海底沉积物层中,当周围环境的温度或者压力发生变化时,其稳定性会受到破坏,诱发坍塌、海底滑坡等地质灾害,对钻井平台、海底电缆等造成巨大破坏。结合南海北部海底陆坡的实际地震资料,首先获得了符合实际情况的储层属性参数,然后基于改进的地质力学模型,获得了相应的力学模型参数,利用孔隙压力平衡方程计算得到地层的有效应力,对天然气水合物分解诱因的海底滑坡的数值模拟,基于强度折减法讨论分析了初始水合物分解量、水合物分解总量等因素引起的水合物储层变化的力学响应,获得了对应的安全系数,实现了水合物分解对海底边坡稳定性影响的分析,为今后水合物开采过程中可能诱发边坡失稳的程度及失稳位置分布预测提供了指导和帮助。Natural gas hydrate mainly occurs in the seabed sediments under low temperature and high pressure.When temperature or pressure changes,the stability of gas hydrate will be damaged,and geological disasters,such as submarine landslide and sediment collapse triggered,which will cause severe damage to offshore platforms and submarine cables.In this paper,based on the seismic data acquired from the submarine continental slope in northern South China Sea,actual reservoir property parameters and corresponding mechanical model parameters are acquired with the improved geomechanical model.Effective formation stress is calculated with the equilibrium equation of pore pressure.Upon the basis,the numerical simulation of submarine landslide induced by the decomposition of natural gas hydrate is made.Then,using the strength reduction method,the mechanical response of hydrate reservoir change caused by initial hydrate decomposition amount and total hydrate decomposition amount is calculated.Upon the correspondent safety factor distribution diagrams,we made a preliminary analysis of undersea landslide caused by hydrate decomposition.The results provide a guidance for prevention of primary or secondary environmental geohazards in the future exploitation of gas hydrate.

关 键 词：天然气水合物 地球物理参数 海底滑坡 数值模拟 南海北部 

分 类 号：P744.4[天文地球—海洋科学] X16[环境科学与工程—环境科学]