中国南方海相层系油气成藏特点与勘探方向

Petroleum reservoiring characteristics and exploration direction in marine strata in southern China

在漫长的地质历史中,中国南方地层经历了多旋回构造运动与强烈后期改造,中、古生界油气的生成、运移、聚集成藏、保存和破坏经历了多期阶段式发展和演化的复杂过程。以四川盆地为代表的构造相对稳定、保存条件好的地区,具有多源供烃、早期聚集、油气转化、晚期定型的特点;中、下扬子中、新生界覆盖区,具有二次生烃、晚期成藏的特点;湘鄂西、滇黔桂等碳酸盐岩裸露区,则表现为早期生烃、后期破坏改造的特点。依据生烃期的早晚以及油气在完成初次聚集后至最终成藏定型是否突破了原始封闭体系,南方海相油气成藏模式可划分为原生型、次生型和再生型3种类型。依据不同地区的成藏条件与特点,南方海相领域的油气勘探应按重点展开、力求突破和区域侦察3个层次进行,即重点展开四川盆地区,力求突破黔西北地区、中扬子江汉平原南部及下扬子句容、海安地区,区域侦察黔南、滇桂及湘鄂西地区。

In the long geological history, the marine strata in southern China have experienced polycyclic tectonic movement and intensive late reformation, and the hydrocarbon generation, migration, accumulation, preservation and destruction in Mesozoic and Paleozoic have experienced multi-stage phasic development and evolution. Areas with relatively stable tectonic settings and well preservation conditions, such as Sichuan basin, are characterized by multiple sources, early accumulation, oil-gas conversion, and late finalization; the Middle and Lower Yangtze areas overlain by Mesozoic and Cenozoic strata are characterized by secondary hydrocarbon generation and late re- servoiring; while the areas with outcropping carbonates, such as western Hunan and Hubei and Yunnan-Guangxi-Guizhou regions, are characterized by early hydrocarbon generation and late destruction and reformation. According to early or late hydrocarbon generation and whether the original sealing systems have been broken in the course of primary hydrocarbon accumulation through to the finalization of the oil and gas pools, the reservoiring models of petroleum in marine strata in southern China can be divided into three types： including primary, secondary and regeneration types. Based on the reservoiring conditions and characterstics in different areas, exploration of marine strata in southern China should be carried out in three different levels： key exploration should be carried out in Sichuan basin, try by all measures to get breakthroughs in northwestern Guizhou, southern Jianghan plain in Middle Yangtze area and Jurong-Hai＇ an regions in Lower Yangtze area, and regional reconnaissance should be carried out in southern Guizhou, Yunnan-Guangxi and western Hunan and Hubei regions.