鄂尔多斯盆地合水地区长7致密油岩性岩相类型识别及其应用

利用岩心、薄片、常规测井、成像测井等资料结合物性分析等,对鄂尔多斯盆地合水地区长7致密油岩性岩相等特征进行了研究。长7致密油储层以砂质碎屑流、浊流和滑塌成因的砂岩为主,烃源岩以泥岩、油页岩为主,根据粒度参数进一步将长7致密油岩性岩相划分为砂质碎屑流细砂岩相、浊流细砂岩相、浊流粉砂岩相、滑塌岩相、半深湖—深湖泥岩相以及油页岩相6类。通过岩心刻度常规和成像测井,建立了不同岩性岩相的测井识别评价标准,并实现了各单井纵向上的岩性岩相的识别和划分。在此基础上,进一步探讨了不同岩性岩相与TOC含量和脆性指数的关系。最后结合试油气资料和油气解释结论,阐明岩性岩相对致密油储层物性和含油气性的定量控制。致密油岩性岩相的研究可为后期成岩相、孔隙结构以及优质储集体预测等奠定基础,为研究区长7致密油的综合评价和有利发育区带预测提供理论指导和技术支持。

Identification of lithology and lithofacies type and its application to Chang 7 tight oil in Heshui area, Ordos Basin

The characteristics of lithology and lithofacies in Chang 7 tight oil in Heshui area, Ordos Basin, were studied by such means as core observation, traditional thin section analysis, conventional logging and imaging logging processing, combined with general physical analysis. Chang 7 tight oil reservoir is mainly sandstone caused jointly by sandy debris flow, turbidity current and slump, and source rocks are mainly mudstone and oil shale. According to grain size parameters, Chang 7 tight oil is further divided into six kinds of lithology and lithofacies, i.e., fine sandstone of sandy debris flow, fine sandstone of turbidity current, siltstone of turbidity current, fluxoturbidite, mudstone of semi-deep water or deep water and oil shale. According to conventional logging and imaging logging scaled by core data, the authors established the evaluation criteria of well logging identification in different kinds of lithology and lithofacies, realized the identification and classification of lithology and lithofacies in a single well on the longitude, and further explored the relationship between different kinds of lithology and lithofacies and TOC content as well as brittleness index. Finally oil-gas testing data and oil-gas interpretation results were combined to illuminate the quantitative control of lithology and lithofacies on physical property and oil-gas possibility of tight oil reservoir. The study of lithology and lithofacies of tight oil can lay the foundation for the further analysis of lithogenous phase and pore structure as well as the prediction of high quality reservoir. It can also provide theoretical guidance and technical support for the comprehensive assessment of Chang 7 tight oil and the prediction of favorable zones for oil-gas reservoir development.