断裂对松辽盆地庆深大气田的控制作用

Controlling role of faults to giant Qingshen Gas Field in SongLiao Basin

庆深气田是我国东部陆上目前发现最大的天然气田,赋存于松辽盆地早白垩世断陷盆地之中,在气藏形成过程中,断裂起到了非常重要的作用。搞清断裂与气田的关系,对于在东部老油田之下的深层,开辟勘探新领域和天然气勘探的新局面有着十分重要的指导意义。通过深入分析断裂与徐家围子断陷、烃源岩、火山岩储层、圈闭、成藏的关系,初步得出了庆深大气田的形成与分布受断裂控制的结论:1.深大断裂控制着盆地边界和深层构造格局,盆地中发育的一系列深大断裂,将盆地分割成东西分带、南北分块的构造格局;2.控陷断裂控制着烃源岩沉积及平面展布,烃源岩主要发育在控陷断裂一侧;3.断裂控制着火山岩的分布范围并且改善其储层物性;4.断裂控制着圈闭类型及其展布方向,深层构造圈闭多沿断裂带呈串珠状分布;5.断裂控制着天然气的成藏。

Qingshen Gas Field, the largest gas field discovered in East China by now, lies in the Early Cretaceous rifted basin of Songliao Basin. In the gas reservoir forming period, fault has played a very important role. To make clear the relationship between faults and gas pool, it is significant to open up a new field for natural gas exploration in the deep layers under eastern mature oilfield. Through the analysis on relationships of the faults with Xujiaweizi fault-depression, hydrocarbon source rocks, volcanic reservoirs, trap and gas accumulation, it is primarily concluded that the formation and distribution of Qingshen Gas Field are both controlled by faults： a. Discordogenic faults, control basin boundary and deep structural framework,namely the basin is divided into the ＂blocks＂ in NS trending and ＂zone＂ in EW trending by a series of discordogenic faults which developed inside the basin; b. Rift-controlling faults govern the sedimentation of hydrocarbon source rocks and its planar distribution; c. Faults control the distribution of volcanic reservoirs and improve their physical properties of reservoir; d. Faults dominate the type and distribution orientation of traps, most deep tectonic traps distributing like a string of beads along the fault belts; e. Faults dominate the accumulation of natural gas.