中国陆相页岩油富集特征

Oil accumulation characteristics of China continental shale

文章对页岩油的富集机理、富集过程和富集主控因素等进行了研究。页岩油比页岩气的发育条件苛刻,分布区域比页岩气局限,勘探难度较大。美国目前勘探开发的页岩油赋存于海相页岩,具有分布范围大、成熟度高、石油密度小、含蜡量低和黏度低等特征,为轻质油;我国页岩油主要为陆相页岩,具有分布范围小、成熟度低、石油密度大、含蜡量高和黏度高等特征,为稠油。美国产油页岩的矿物组成的石英和碳酸盐多为生物来源,石英含量、碳酸盐含量与有机碳含量有很好的正相关关系,与页岩油的含量也是正相关关系,且有利于后期压裂改造;我国陆相含油页岩的石英多为碎屑来源,碳酸盐多为化学沉积,石英含量、碳酸盐含量与有机碳呈负相关关系,与页岩油的含量也是负相关关系,且不有利于后期压裂改造。海陆相页岩油特征的差异可能是导致我国页岩油产量较低的原因,制约了页岩油的勘探开发。我国陆相断陷盆地页岩油勘探应寻找页岩有机质成熟度相对较高的深凹区和砂岩夹层发育的斜坡区,深凹区具有"油稀、高压和可改造"等特点,斜坡区具有"夹层发育、可改造"等特点。

The accumulation mechanism and characteristics of shale oil were investigated.In comparison with shale gas,shale oil is more strict in accumulation conditions,more limited in distribution area,and more challenge in exploration.In the USA,shale oil is a kind of light oil in the marine shale and it is characterized by large distribution,high maturity,low density,low wax content and low viscosity.While in China,shale oil is a kind of heavy oil in the continental shale and it is characterized by small distribution area,low maturity,high density,high wax content and high viscosity.For the marine shale in USA,the quartz and carbonate were mostly biological sources.The quartz has a good positive correlation with the total organic carbon.It controls the oil content and is conducive to the fracturing.While for the continental shale in China,the quartz was of clastic source and the carbonate was chemical deposition.The quartz has a negative correlation with the total organic carbon and is not conducive to the fracturing.These differences may be the reasons of low shale oil production,which severely restricted the exploration and development of shale oil in China.It suggests that the shale oil exploration should focus on areas with relatively high maturity in central depressions and areas with highly developed sandstone interbed on slopes.The former features in‘light oil,high pressure and easy fracturing＇,while the latter is characterized by‘well developed interbed and easy fracturing＇.