中国南方海相石油地质特征及勘探潜力

中国南方及邻区的基本构造格架可概括为五个陆缘造山带、三个较稳定地块、一个加里东构造域和一个陆内基底拆离造山带。基本地层层序格架可归纳为六个一级层序及相应的沉积构造旋回,沉积构造格架及多旋回构造演化史决定了南方海相石油地质的基本特征。自震旦纪至中三叠世在南方发育了两个世代的海相原型沉积盆地,均在南北两大陆边缘发育了丰富的优质烃源岩,包括四套区域主力烃源层和六套地区性烃源岩,并形成五套好的区域性盖层以及包括风化壳、裂缝、礁滩及白云岩等多种储集体。印支—早燕山造山期原型大陆边缘盆地和前陆盆地,曾形成五个原始超油气系统,后期的高热演化,使其在现今多转化为含气系统。现实的含气系统只能残留赋存于现今有效保存单元之内,具有多源多期成烃、晚期复合成藏等基本特点。近期油气资源评价认为,南方海相资源量为8.2882×10~(12)m~3气当量,油气勘探潜力大。今后的有利勘探方向包括鄂西渝东地区及川东北地区等七个区块。

Petroleum Geology of Marine Sequences and Exploration Potential in Southern China

The main part of the southern China geotectonically belongs to South China Plate,which covers an area of nearly 2× 10~6 km~2.The basic tectonic framework of the studied region can be summarized as five continental margin orogenic belts, three stable landmasses,one Caledonian tectonic domain and one intracontinental basement decoupling orogenic zone in South China Continent and its surroundings.The basic frame- work of strata can be classified into six sequences of Grade I and corresponding sedimentary cycles.Basic characteristics of marine petroleum geology in the studied region are controlled by basic deposition-tectonics framework and multicyclic tec- tonic evolutions.During Sinian-Middle Triassic period,abun- dant excellent source rocks deposited in the northern and southern margin areas of the continent,including the 4 sets of regional major hydrocarbon source strata and the 6 sets of local source rocks,and formed five sets of excellent regional seals and many kinds of important reservoirs consisting of weathering crust,fissure,reefs and dolostone because of polycyclic de- velopment of the prototypal marine sedimentary basins.Five o- riginal super-petroleum systems had ever formed in the original epicontinental basins during Indosinian-early Yanshanian oroge- nies.Owing to high maturity of organic matter in marine source rocks,the original petroleum systems were evolved as the cur- rent pure gas systems.The present pure gas systems can only exist residually in entirely or locally enclosed effective preser- vation units because of later multiphase tectonic reconstruc- tions.Multiphase and multisource hydrocarbon generation and later-formed composite hydrocarbon accumulation are the basic features of marine petroleum systems in southern China.Re- cent resource evaluation has showed that there is a very great potential of hydrocarbon exploration in the southern China re- gion where the total hydrocarbon resources reach to 8.29× 10~(12)m~3.It is suggested that seven favorable prospecting provinces can be selected,which include northeastern Sichuan Basin,western Hubei-eastern Chongqing area and others.