大庆长垣以东地区深层天然气成藏的控制因素及成藏模式

Factors Controlling the Formation of Gas Reservoirs and Gas Accumulation Models in Daqing Placanticline and Its Eastern Area

通过长垣以东地区深层天然气分布特征研究 ,提出了深层天然气成藏的 4种控制因素 ,即气源条件、盖层条件、断裂和不整合面 ,并对它们在气藏形成中所起作用进行了深入分析。在此基础上 ,提出了该区深层天然气成藏的4种模式。即天然气沿不整合面短距离运移基岩风化壳成藏模式 ,天然气沿裂缝运移源岩区内火山岩成藏模式 ,天然气沿不整合面或砂体和断层长距离运移古隆起之上各种类型圈闭成藏模式 ,天然气沿砂体侧向运移地层超覆圈闭成藏模式。最后指出了该区深层有利钻探靶区。

Through studying gas distribution characteristics of deep strata in Daqing placanticline and its eastern area, this paper puts forward four factors controlling the formation of gas reservoirs in deep strata. They include conditions of gas source rock, caprock, fault and surface of unconformity. And furthermore we analyzed their controls the formation of gas reservoirs. Based on these, the paper delineates four kinds of gas accumulation models in deep strata, including the accumulation models of gas migration shortly through surface of unconformity into weathering crust of basement, gas migrating through fracture into volcanic rock in gas source rock,gas migrating through surface of unconformity or sandbody and fault into all kinds of traps over the ancient uplift,as well as the accumulation model of gas migrating laterally through sandbody into stratigraphic overlap traps, finally this paper prospect the favorable gas exploration targets in deep strata.