鄂尔多斯盆地冯地坑—洪德地区长6油层组成岩作用研究

长6油层组是鄂尔多斯盆地冯地坑—洪德地区的重要勘探目的层。因该油层组具有粒度细、成分成熟度低、磨圆度较差、分选性较差的岩石学特征,所以,研究对其储层物性有控制作用的成岩作用具有极其重要的意义。结合单偏光显微镜、扫描电镜、阴极发光、X-射线衍射分析及流体包裹体均一温度测试等资料,对研究区长6油层组的成岩作用进行了系统研究,结果表明：该油层组主要成岩作用有压实作用、压溶作用、胶结作用、交代作用和溶解作用,且成岩演化主要处于中成岩阶段A期。在成岩作用研究基础上,综合黏土矿物成分、胶结物及孔隙的发育状况,把长6油层组划分为5个成岩相：高岭石胶结相、绿泥石胶结相、铁方解石胶结相、绿泥石薄膜＋长石溶蚀相以及长石溶蚀相。其中,绿泥石薄膜＋长石溶蚀相和长石溶蚀相为最有利储集相带。

Diagenesis of Chang 6 oil reservoir set in Fengdikeng-Hongde area,Ordos Basin

Chang 6 oil reservoir set is the major exploration target in Fengdikeng-Hongde area of Ordos Basin. Because it has such petrological characteristics as fine grain size, low compositional maturity, poor psephicity and worse sorting, it is extremely important to carry out study on the diagenesis which controls the physical properties of reservoir. Combining with the data from plainlight microscope, scanning electronic microscope, cathodoluminescence, X-ray diffraction analysis and homogenization temperature test of fluid inclusion, the diagenesis of Chang 6 oil reservoir set was studied systematically. The result shows that the main diagenesis types include compaction, pressure solution, cementation, metasomasis and dissolution, and its diagenetic evolution lies mainly in the middle diagenetic stage A. Based on the diagenetic study and combined with clay mineral components, cement and growing situation of pores, the Chang 6 oil reservoir set is divided into five kinds of diagenetic facies, namely kaolinite cementation, chlorite cementation, ferrocalcite cementation, chlorite film plus feldspar dissolution and feldspar dissolution, among which the latter two kinds are the most favorable reservoir facies.