非常规含气系统的研究和勘探进展

从含油气系统的观点出发，分别总结了煤层气、盆地中心气、裂缝型页岩气、浅层生物气和天然气水合物五类非常规含气系统的地质和地球化学特征，修改和补充了传统油气系统的概念，为天然气新领域的开拓和发展提供了新的思路。常规天然气藏为浮力驱动的存在于构造或地层圈闭中的独立气藏，而非常规天然气藏一般不是浮力驱动的聚集气藏，它们在区域上呈连续弥散的聚集，常常与构造和地层圈闭无关，因此，它们的成藏要素和过程与常规天然气藏有所区别。在煤层气和页岩气中，烃源岩既是储层，又是盖层且运移距离很短；储层多为低孔隙度、低渗透性的裂缝型储层，主要为毛细管力和水力封闭，大型煤层气藏可以出现在向斜构造中。

ADVANCES IN THE RESEARCH AND EXPLORATION OF UNCONVENTIONAL PETROLEUM SYSTEMS

In terms of view of petroleum system,this paper summarizes geologic and geochemical characteristics of unconventional petroleum systems of coalbed gas,basin-centered gas,fisswred shale-gas,low-layer biogenic gas and gas hydrate,respectively,thus modifying and expanding upon traditional concepts of petroleum system,and providing a new thought for opening up new frontiers of natural gas resources.Conventional gas resources are buoyancy-driven deposits,occurring as discrete accumulations in structural and stratigraphic traps,whereas unconventional gas resources are generally not buoyancy-driven accumulation.They are regionally pervasive,most commonly independent of structural and stratigraphic traps,thus possessing different key elements and processes from conventional petroleum systems.In petroleum systems of coalbed gas and shale-gas,the source rock is both reservoir and often the cap rock,with short migration distance.The reservoirs are characterized by low porosity,low permeability,fractural opening,as well as capillary and hydrodynamic trapping.Huge coalbed gas accumulations may be found in the structural low.