天然气水合物与传统油气资源共生成藏模式初探

天然气水合物与常规油气资源的成藏在时空上存在密切联系,在一定条件下可以共生成藏。存在泄漏共生、封盖共生和遮盖侧储三种基本的共生成藏模式。泄漏共生模式是先期形成了传统油气藏,而后由于发生油气泄漏并在其上方形成天然气水合物,其特征是在水合物的下方生、储、盖齐备;封盖共生模式则是先在上部形成天然气水合物,同时作为下部传统油气藏的盖层,其特征是水合物之下的传统油气藏具备生、储成藏条件,但缺乏盖层成藏要素;遮盖侧储模式是由于水合物矿藏的遮盖作用,迫使在下部形成的烃类物质向上运移时改道,在旁侧具成藏条件的邻区成藏。实际的地质成藏可能会出现这些基本模式的组合形式。

Accumulation Coexistence Models of Natural Gas Hydrate and Conventional Hydrocarbon:An Approach

Natural gas hydrate may be closely related with conventional hydrocarbon resources in time and space.In some appropriate conditions,natural gas hydrate can accumulate along with or coexist with conventional hydrocarbon in relative reservoirs.On the base of this research,three kinds of basic accumulation coexistence models are suggested,which are the leaking accumulation,the capping accumulation and the capping side-accumulation coexistence models.The Leaking accumulation coexistence model means that conventional hydrocarbon has accumulated first in lower reservoirs and then leaks up to form gas hydrate in upper reservoirs,which is characteristic of a complete source-reservoir-caprock assemblage under the gas hydrate reservoirs.The capping accumulation coexistence model refers that gas hydrate accumulates in upper reservoirs and meanwhile the gas hydrate reservoirs act as the cap rocks of the lower conventional hydrocarbon reservoirs,which is characterized by a nice source-reservoir assemblage but lack of cap-sealing condition.The capping side-accumulation coexistence model implies that due to covering of the upper gas hydrate reservoirs,the lower hydrocarbon has been barriered as it migrate up and accumulate side away into the adjacent reservoirs.Actual hydrocarbon accumulation may be any assembled pattern among these models.