松辽盆地南部长岭断陷区深层构造特征与天然气聚集

在充分利用二维地震大剖面、三维地震资料以及钻/测井信息的基础上,结合高精度重、磁、电信息,系统地解剖了长岭断陷的区域地质结构,认为长岭断陷区为非单一简单断陷,而是由多个主次断陷组成的复式断陷群,且与北部的古龙断陷连为一体。在连片工业制图的基础上,进行了构造单元及区带划分,分析了主要断裂的几何学及运动学特征,认为乾安断裂、前神字井断裂、黑帝庙断裂、孤西断裂、孤店断裂、大安断裂、哈尔金断裂与顾家店—伏龙泉断裂控制了长岭断陷的地层发育及断陷结构,其中乾安断裂、前神字井断裂、黑帝庙断裂为最主要的控凹断裂。研究了断陷构造演化,将其分为断陷基底形成期、断陷发育期及断陷改造期等3个阶段。在油气地质条件分析基础上,研究了不同类型天然气的成藏特征,认为深层烃类气为煤型气,主要来自受断陷沉积控制的沙河子组和火石岭组,深层二氧化碳气为无机成因,主要来源于深层地幔,同时指出了有利勘探方向。

The Characteristic of Deep Structure and Natural Gas Accumulation in Changling Fault Depression, Southern Songliao Basin

With full use of 2D regional seismic profile,3D seismic data,drilling/well logs information,and high-resolution gravity-magnetic-electric information,the regional geological texture of Changling fault depression in Southern Songliao Basin is systematically dissected.It is believed that Changling fault depression connecting with Gulong fault depression in north is a group of composite fault depressions including lots of primary and secondary sags rather than a single fault depression.In the light of industrial mapping,structural element and zone are divided;geometric and kinematical characteristics of major fractures are analyzed.The strata development and the depression framework are controlled by Qian'an fault,Qianshenzijing fault,Heidimiao fault,Guxi fault,Gudian fault,Daan fault,Haerjin fault and Gujiadian-Fulongquan fault.Among them the Qian'an fault,Qianshenzijing fault and Heidimiao fault are foremost faults controlling depression.The evolution history of the depression is divided into three phases,i.e.basement formation phase,rifting phase,and fault depression reform phase.The reservoir formation condition for various types of gas reservoirs is studied in term of petroleum geology.It is recognized that the deep-seated hydrocarbon gas is coal-type gas,which came from the Shahezi Formation and Huoshiling Formation which deposited in depressing phase,and the deep seated CO2 gas is anorganogene,which mainly came from mantle,and the direction for prospective zone exploration is pointed out.