叠合盆地油气成藏体系研究思路与方法——以准噶尔盆地中部地区油气藏为例

Methods in Studying Petroleum Accumulation Systems in a Superimposed Basin: A Case Study of Petroleum Reserviors in the Central Junggar Basin

以准噶尔盆地中部地区油气藏为例,阐述了叠合盆地油气成藏体系研究的基本思路和方法,归纳为"一个中心,两条途径"。一个中心是指以油气藏为中心进行剖析研究,两条途径是指采用有机和无机地球化学相结合的研究方法。在准噶尔盆地中部地区的实例研究结果表明,根据原油的有机(生物标志物)地球化学分析,研究区至少存在2大油气成藏体系,即盆1井西凹陷东环带地区二叠系成藏体系、莫索湾中东部地区二叠系和侏罗系成藏体系。再通过无机地球化学(储层成岩方解石)分析,发现研究区还存在另外2个成藏体系,即东道海子凹陷周边地区二叠系和侏罗系成藏体系、石东地区二叠系成藏体系。在此基础上,进一步评价了各成藏体系中的油气潜力,以为区域油气勘探提供参考。因此,油气成藏体系的研究有助于加强对勘探的指导;有机和无机地球化学相结合的研究方法相互补充,是对过去通常主要根据有机地球化学方法进行分析的拓展与补充完善,形成了新认识,值得在今后的油气成藏体系研究中加强深入探索。

The basic method in studying petroleum accumulation system in superimposed basins was demonstrated by a case investigation in petroleum reserviors of the central Junggar Basin.The method can be summarized into two points.The first is that the study is focused on petroleum reserviors.The second is that both organic and inorganic geochemical methods are used.The case study in the central Junggar Basin shows that the area has at least two petroleum accumulation systems according to the organic （biomarker in particular） studies,i.e.,the Permian system in the eastern area to the Penyijingxi sag,and the Permian and Jurassic system in the middle-eastern Mosuowan area.The study using inorganic geochemical method on reservoir diagenetic calcite shows that the area has two additional petroleum accumulation systems,i.e.,the Permian and Jurassic system in the surrounding area of the Dongdaohaizi sag and the Permian system in the Shidong area.Moreover,the potential of retaining oil and gas for each petroleum accumulation system was assessed to provide information for the exploration.Therefore,it is concluded that the research method of petroleum accumulation system can help to improve the guidance on petroleum exploration,and the organic and inorganic geochemical methods are complementary to each other.In particular,the new application of the inorganic geochemical method is a supplement to and improvement for the previously and commonly used organic geochemical method,and thus deserves to be studied further.