苏南块体的深部构造及其油气前景

苏南块体中地壳存在一低速层,Vp约为5.8～6.0km/s,它与地下高导层相对应,电阻率仅4～20Ω·m,是中地壳塑性层的反映;苏南块体属于太平洋型块体,是有利的油气分布区块;它处在地球化学急变带上,壳幔相互作用比较强烈,故该区的油气受深部因素的影响或控制比较明显,是有利的深部无机成因油气分布区。中地壳低速高导层(蛇纹石化橄榄岩)构成油气“发生器”;上地幔则是“原料库”;沉积盆地是“存储器”。当地幔流体中H2缺失或不足时便没有烃生成,只能形成CO2或以CO2为主的气藏。黄桥CO2气藏已被公认是幔源无机成因气体,实质上是由在中地壳进行的不完整费-托合成反应所致。镇江—常州—无锡—苏州—昆山一带为油气富集带,具有深部成因油气的良好远景。

Deep Tectonics and Hydrocarbon Potential in South Jiangsu Crust Block

South Jiangshu crust block is in the geochemical steep zone that is a favorable region of inorganic-originated hydrocarbon accumulation where there is intensive interaction between the crust with the mantle in deep. If H2 was lacked or not enough in the mantle fluid there,no hydrocarbon would be produced so that CO2 or CO2-dominated gas reservoirs would form. Huangqiao CO2 Gas Reservoir is ecognized as an instance that CO2 gas is inorganic-originated,substantially resulted from incomplete composed Fischer-Tropsch reaction within the middle crust. It is suggested that there is a well-potential zone of deep hydrocarbon concentration along the Zhenjiang-Changzhou-Shuzhou-Wuxi-Kunshan area.