天然气水合物藏的界定及思考

 在回顾致密气、页岩气、煤层气等非常规天然气藏定义的基础上,基于天然气水合物藏的特征,认为天然气水合物藏是指具有一定量的甲烷等气体运移到温度-压力适宜的地层,并以固态形式赋存于地层/松散沉积物中的天然气水合物资源及其与之有直接关联的天然气聚集。因此,在开展天然气水合物资源勘查与评价时,应当查明天然气水合物层下部游离气状况,存在游离气层的"固-气两层楼式"天然气水合物藏是当前有利的天然气水合物开发靶体。分析认为神狐海域天然气水合物属于"固-气两层楼式"天然气水合物藏,在进行资源评价和试采时,应该对天然气水合物层和游离气层进行统一考虑,从而有望进一步提高单井日产量和经济效益,促进天然气水合物的勘探与开发。

Definition and thinking on natural gas hydrates reservoir

Based on the definitions of unconventional gas reservoirs such as the tight gas, the shale gas and the coal bed methane, and the characteristics of the natural gas hydrate reservoir, the natural gas hydrate reservoir is defined as the natural gas hydrate accumulation with a certain amount of methane & other gases, migrated to appropriate strata with appropriate temperature and pressure, then stored in the formation/loose sediments in solid form, and the free gas accumulation directly associated with the natural gas hydrate accumulation. During the exploration and the evaluation of the natural gas hydrate resource, it is important to ascertain the free gas condition in the lower part of the natural gas hydrate accumulation. Characterized by the underlying free gas accumulation, the "solid-gas two-story-architecture style" natural gas hydrate reservoir is the current favorable exploitation target and the natural gas hydrate reservoir in Shenhu area is considered to be such kind of reservoir. When carrying out the resource evaluation and the test in the area, the natural gas hydrate accumulation and the free gas accumulation should be taken as a whole, which is expected to further improve the single well production and the economic benefits, promoting the exploration and the development of the natural gas hydrate.