湖相云质岩致密油储层非均质性特征及其定量表征方法

As an important continental tight oil type in China, tight oil in lacustrine dolomitic rocks has great resource potential. However, due to the complex heterogeneity of the reservoir, the main controlling factors of microscopic pore structure diversity as well as the quantitative controlling relationship between microscopic pore structure and macroscopic heterogeneity are weakly studied. Additionally, the scale effect between different data leads to a relatively low accuracy in tight oil reservoir characterization with multi-data integration. This subject aims to address these issues through the practical anatomy of the tight oil reservoir in lacustrine dolomitic rocks, the Permian Lucaogou Formation in the Jimusaer Sag, Junggar Basin. Various techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), high-pressure mercury injection (HPMI) and N2 adsorption/desorption measurements (N2GA) are applied to qualitatively describe and quantitatively characterize the microscopic pore structure of the reservoir, and the main controlling factors of pore structure and reservoir quality are further determined. Rock physics analyses are conducted to build a quantitative characterization method of microscopic pore structure through well logging and seismic data. Lastly, the fractal theory is introduced and the fractal dimension is used to bridge the gap between the differences caused by the measurement scale, and a set of quantitative characterization method integrated of multi-scale data is then established to comprehensively evaluate the reservoir quality. Through this study, the insights of tight oil reservoirs in continental lake basins can be improved and a set of systematic characterization method can be established, which is of important theoretical and practical significance.

作为中国陆相致密油的一种重要类型，湖相云质岩致密油资源潜力巨大。但由于其复杂的非均质性特征，导致储层微观孔隙结构差异主控因素，微观孔隙结构对储层宏观非均质性的控制作用、定量表征关系研究薄弱。另外，由于资料之间的尺度效应，导致致密油储层表征过程中多数据融合的表征精度较低。本课题拟通过准噶尔盆地吉木萨尔凹陷二叠系芦草沟组湖相云质岩致密油储层的实际解剖来探讨问题的解决方案。通过扫描电镜、X-衍射、高压压汞和氮气吸附等实验手段，对储层微观孔隙结构进行定性描述和定量表征，确定孔隙结构及储层质量主控因素；通过岩石物理分析，确定测井、地震尺度微观孔隙结构的定量表征方法。最终，以分形理论为指导，将测量尺度带来的差异用分形维数建立关系，形成一套多尺度数据融合的定量表征方法，并对储层质量进行综合评价。通过该研究，可以完善关于陆相湖盆致密油储层的认识，并形成一套系统的表征方法，具有重要的理论意义和现实指导意义。

湖相云质岩致密油储层资源潜力巨大，但由于其复杂的非均质性特征，导致储层微观孔隙结构差异主控因素，微观孔隙结构对储层宏观非均质性的控制作用、定量表征关系研究薄弱。另外，由于资料之间的尺度效应，导致致密油储层表征过程中多数据融合的表征精度较低。本课题通过准噶尔盆地吉木萨尔凹陷二叠系芦草沟组湖相云质岩致密油储层的实际解剖确定了问题的解决方案，并取得如下成果与认识：.（1）开展了吉木萨尔凹陷芦草沟组精细地层及沉积体系分析。将目的层划分为2个段，4个砂组，重点层划分精度达到小层-单层级别；根据岩心、测录井等资料，共识别出了3类亚相6种微相，包括浅湖亚相中的砂滩、浅湖泥微相，浅湖-半深湖亚相中的云坪、混合滩、浅湖-半深湖泥微相，半深湖亚相中的半深湖泥微相，并确定了沉积体系分布、演化。.（2）明确了云质致密油储层特征、储层质量主控因素。基于岩心描述、XRD、高压压汞、氮气吸附等实验分析结果，确定了目的层6种岩性、4类孔隙结构特征，并基于压汞、氮气吸附曲线形态及分形特征将储层划分为3类。沉积微相类型、岩性特征、岩矿组成、物性特征以及孔隙结构非均质性都对储层质量具有影响，其中以孔隙结构非均质特征及孔隙度为主控要素。.（3）建立了多尺度数据融合的储层非均质性定量表征方法。以R/S维数为基础，以孔隙结构参数为对象，确定了测井、地震尺度3类不同储层的划分标准，实现了4ms时窗约束下的地震、测井数据最佳匹配；在此基础上，通过井震数据融合实现了储层的分类表征。.（4）开展了储层质量综合评价。综合R/S维数、孔隙度以及脆性指数，利用熵权法确定了云质致密油储层的综合评价指数，明确了其分类标准，并在此基础上，实现了3类不同甜点储层的分布预测表征。