松辽盆地北部深层地质特征与天然气勘探方向

松辽盆地深层包括上侏罗统火石岭组、下白垩统沙河子组、营城组断陷地层和下白垩统登娄库组、泉头组一+ 二段坳陷地层。断陷地层分布于一系列分割断陷中,控陷断裂为北北东向和北西向,断陷沿嫩江断裂带、孙吴—双辽断裂带和哈尔滨—四平断裂带分布。火石岭—沙河子组沉积时期为断陷大规模伸展期,沙河子组沉积末发生了大规模的反转,奠定了断陷期地层的改造格局。断陷期湖相泥岩和煤层是最重要的生烃层系,以登二段、泉一+ 二段和青一段三套区域盖层分开了四套天然气生储盖组合。临近生烃凹陷的古隆起、控陷断裂带和断陷内的古构造是天然气聚集的有利区带。

Geological Characteristics of Deep Layers in Northern Part of Songliao Basin and Orientation for Natural Gas Exploration

The deep layers of Songliao Basin include Jurassic Huoshiling Formation, Lower Cretaceous Shahezi Formation and fault-depression stratum ofYingcheng Formation, and Lower Cretaceous depression strata of Denglouku Formation and Mem.I+II of Quantou Formation. The fault controlling the depression is in the NNE and NW directions. The fault depression is distributed along Nenjiang fracture belt, Sunwu-Shuangliao fracture belt and Harbin-Siping fracture belt. The sedimentary time for Huoshiling-Shahezi Formation is the time for the fault depression to be extended at a large scale. At the end of sedimentation for Shahezi Formation, the large-scale reversal takes place, laying the foundation for reformation of strata in the fault depression period. Mudstone of lake facies and coal measure are the most important hydrocarbon source stratum series during the faulted depression period. The three sets of regional cap rock-Mem. II of Denglouku Formation, Mem.I and II of Quantou Formation and Mem.I of Qing shankou Formation- separate four sets of natural gas source-reservoir-caprock assemblages. Close to the palaeohigh of the source depression, the fracture belt controlling the depression and the palaeostructure in the fault depression are the favorable zone for natural gas accumulation.