天然气水合物在油气藏形成过程中的封盖作用——谈造山带中烃源岩对盆地区油气资源的贡献

Sealing of Natural Gas Hydrate during Hydrocarbon Accumulation: A Discussion on the Contribution of Source Rocks in Orogenic Belts to Hydrocarbon Resource in Basins

在中国的造山带中普遍发育优质烃源岩,它们形成于海槽环境,而海槽环境也是形成天然气水合物的有利环境。水合物有良好的封盖作用,其下的油气受到封盖会向相邻的台地区运移,即油气从古海槽区(现今为造山带)向台地区(现今为盆地区)转移。因此造山带中的烃源岩对盆地区油气资源应有积极贡献。认为现今台西南海域的水合物与相邻油气藏具有同源性,这是水合物的封盖作用与油气藏形成之间具有密切联系的生动实例。四川盆地有限的烃源岩分布不能提供巨大的天然气储量,周边造山带可能也提供了相当的资源量。建议在四川盆地和秦岭造山带中系统采集气-液包裹体,以对比它们的亲缘关系,借以验证造山带中的烃源岩是否对盆地区的天然气成藏具有贡献。

Good hydrocarbon source recks generally develop in orogenic belts in China. These source rocks formed in paleotrough environment,which is also the favorable environment of natural gas hydrate accumulation.Gas hydrate is of sealing hydrocarbon well. Hydrocarbon under the control of hydrate seal may migrate into neighboring areas, i.e. from the paleotrough areas （present-day orogenic belts） to platform areas （present-day basins）. It is deemed that the source rocks in orogenic belts should have great contribution to hydrocarbon resource within basins.It is suggested that gas hydrate under the present southwestern sea area of Taiwan have an affinity with hydrocarbon reservoirs in neighboring areas. Also a considerable hydrocarbon resource in Sichuan Basin might be supplied by the orogenic belts of the basin margins.