东海西湖凹陷反转构造与油气

RELATIONSHIP OF INVERSION STRUCTURE AND OIL AND GAS PROSPECT IN XIHU DEPRESSION IN EAST CHINA SEA

本文从东海西湖凹陷的地质构造特征出发，根据西湖凹陷所处的西太平洋特殊地质构造位置，结合反转构造理论，认为自新生代以来，西湖凹陷长期处于太平洋板块向欧亚板块斜向俯冲的挤压状态。随时间的推移凹陷的边界条件不断地变化，由此引起应力场的改变，继而造成构造反转。西湖凹陷曾经历过五次构造反转期。盆地的复合，构造的叠加，断层性质的改变，对油气生成、运移和储集起着决定性的作用。本文最后用反转构造理论对油气远景作了简单的探索。认为早期由正断层形成的地堑、地垒、断块及晚期褶皱、逆断层发育的地区应作为油气勘探的重点。前者，早期局部张应力形成的正断层，在区域压应力的持续作用下，后期虽然在形式上还是正断层，但晚期已转变为压性的，对油气聚集较为有利。后者，由于新生代早期的巨厚沉积，并且发育着张性断裂，这些对油气的生成和运移有一定好处。

By analyzing geologic characters and the special place and widely scattered inversionstructures of Xihu depression,it is concluded that since Cenozoic Era Xihu depression isin the long-term state of extruding.In the depression,continuous changing of peripherycondition results in variation of tectonic stress field and this field gives rise to inversionof structure,There were five periods of inversions of struture in Xihu depression,Over-lapping of new basins and structures and transformation of fault nature take immense ef-fects on generating,migtating and gathering of oil and gas,Finally.application of thetheory of inversion structure gives some explanations to the prospect of Oil and gas.Thispaper proposes two promising areas. One is the area of graben,horst and fault blocks re-sulting from early-stage normal faults,the other is the area where folds and reversefaults are well developed with thick-bedded sedimentary layers.