天然气水合物发育的构造背景分析

大量的钻孔资料和地震剖面显示主动大陆边缘的增生楔和被动大陆边缘的俯冲-增生楔、断裂-褶皱系、底辟构造或泥火山、滑塌构造、海底扇、"麻坑"构造和陆地多年冻土区等多种地质构造背景是形成天然气水合物的有利场所,可形成构造圈闭型天然气水合物矿藏。这些地质构造背景一方面大多是深部热成因气、生物成因气或混合成因气体或流体向上运移到海底的通道,形成天然气水合物矿藏;另一方面也可能造成天然气水合物的温压环境改变,致使天然气水合物分解。海底滑塌亦可能是天然气水合物分解所致,是潜在的地质灾害。

Tectonic Settings Analysis of Gas Hydrate Deposits Development

Natural gas hydrates are an important potential energy source for the 21st century. Based on the published drilling data and seismic reflection profiles, the accretionary prism, fault-folded system, mud volcano/mud diapir, slide, submarine fan, pockmark and permafrost region were recognized for the tectonic settings of gas hydrate. On the one hand, this tectonics can be regarded as good conduits for the formation of gas hydrate deposits, and on the other hand, the deposits can be destructed by this tectonics. Gas hydrate concentration in sediments is relatively high because of rapid transport of gas from great depth along these highly permeable tectonic conduits. Hence, gas hydrates can be dissociated when their equilibrium conditions are broken by the tectonic movements or the heat flow transported along these tectonic conduits. This gas hydrate dissociation may also lead to the submarine landslide.