鄂尔多斯盆地黄陵探区细粒浊积砂体低渗致密机理

浊积砂体是鄂尔多斯盆地三叠系延长组黄陵探区内重要的油气储层类型，受沉积及成岩的影响，物性差，属低渗致密砂体储层。为了进一步揭示研究区浊流沉积特征，分析其致密机理，文中首先从露头调查、岩心观察及物源分析入手，总结了细粒浊流沉积典型的识别标志和沉积特征；其次运用扫描电镜、薄片分析、阴极发光、恒速压汞等测试手段，从沉积、成岩及微观孔喉结构3个方面，探讨了物性变差储层致密的原因。研究表明：原始沉积环境及其物质条件，是研究区储层致密的基础原因；在成岩过程中，溶蚀作用欠发育，方解石、白云石等碳酸盐胶结，是储层进一步致密的关键因素；而孔隙发育程度及孔喉配位关系差，特别是主流喉道偏细（0.38~0.76 μm），是储层致密的微观因素。

The fine-grained turbidite sand body is a major reservoir type of Triassic Yanchang Formation in Huangling exploration area of Ordos Basin. The reservoir is classified to be low permeability tight sand body as the influence of sedimentary and digenesis. In order to reveal further the turbidite sedimentary characteristics and the mechanism of densification, the typical identification mark and sedimentary characteristics of fine-grained turbidite sediments are concluded by outcrop investigation, core observation and provenance analysis. Using scanning electron microscope, thin section analysis, cathodoluminescence and rate-controlled mercury penetration, the densification reason of poor physical property reservoir is discussed from sedimentation, diagenesis and microcosmic pore structure. Study shows that the original sedimentary environment and material conditions are the fundamental reasons of dense reservoir. In the process of digenesis, the development of dissolution is relatively poor and the carbonate cementation such as calcite and dolomite is the key factor of dense reservoir forming. The poor matching relationship of pore development degree and pore-throat coordination, especially the thin mainstream throat(0.38-0.76 μm), is the micro-factors of dense reservoir forming.

10.6056/dkyqt201501006