关于吉木萨尔凹陷页岩油的思考

关于准噶尔盆地吉木萨尔凹陷芦草沟组原油类型,历来有2种观点,一种观点认为属于致密油,另一种观点认为属于页岩油。参照《致密油地质评价方法》和《页岩油地质评价方法》这2个国家标准,厘定了吉木萨尔凹陷芦草沟组原油的归属。研究表明,依据源储关系和单层厚度统计数据,认为吉木萨尔凹陷芦草沟组原油为页岩油。依据页岩油的赋存条件、源储关系和富集模式,将吉木萨尔凹陷芦草沟组页岩油划分为夹层富集型页岩油。从烃源岩地球化学参数、储集层岩性和物性、油藏参数、裂缝发育情况和脆性特征几个方面,对比了国内外典型页岩油特征。结果表明,吉木萨尔凹陷芦草沟组页岩油为低—中成熟度页岩油,烃源岩在早期就开始大量生排烃;储集层孔隙度相对较高,但渗透率明显偏低;油藏含油饱和度较高,但原油密度大,黏度高,气油比低,流动性差;储集层天然裂缝不发育,岩石力学脆性较差。

Discussion on Shale Oil in Jimsar Sag,Junggar Basin

Two conclusions have been existent about the crude oil of the Lucaogou formation in the Jimsar sag, Junggar basin. One conclusion classifies the crude oil as tight oil, and the other as shale oil. According to two national standards - Geological Evaluation Method for Tight Oil and Geological Evaluation Method for Shale Oil, the classification of the crude oil in the Lucaogou formation is determined. The studies show that, based on the source-reservoir relationship and layer thickness statistics, the crude oil in the Lucaogou formation of the Jimsar sag is shale oil; based on the occurrence, source-reservoir relationship and oil accumulation model, the oil is determined as shale oil which accumulates between layers. In terms of the geochemical parameters of the source rock, the lithology and physical properties of the reservoir, the parameters of the oil reservoir, fracture development and brittleness, this study investigates how the characteristics of the shale oil in the Lucaogou formation are different from the typical shale oil at home and abroad. The results show that the shale oil in the Lucaogou formation is of low to middle maturity, but a large amount of hydrocarbons have been generated and expelled in the early stage; the reservoir has high porosity, but its permeability is obviously low; the oil saturation of the reservoir is high and the oil is characterized by high density, high viscosity, low gas-oil ratio and poor fluidity. Natural fractures in the reservoir are not developed, and the brittleness calculated with the rock mechanical method is poor.