鄂尔多斯盆地白豹地区长6 砂岩成岩作用与成岩相研究

上三叠统延长组6 段是鄂尔多斯盆地白豹地区重要的勘探目的层, 也是典型岩性- 地层油藏。文章在岩心和沉积相分析基础上, 结合铸体薄片、扫描电镜和电子探针等分析化验资料, 对长6砂岩的成岩作用进行系统研究, 确定对储层起破坏作用的成岩作用主要有压实- 压溶作用、胶结作用和充填作用, 起建设性成岩作用的主要有早期绿泥石和白云石的环边胶结作用、溶蚀作用和破裂作用。综合成岩作用方式的组合类型和演化序列, 认为长6 砂岩的成岩演化主体已进入中成岩阶段B 期。在建立成岩演化模式的基础上, 对成岩相组合特征进行了初步研究, 划分出压实- 胶结成岩相组合、压实成岩相组合和胶结- 溶蚀成岩相组合, 分析了成岩相组合与储层发育的关系及其区域分布规律, 为进一步的岩性- 地层油藏的成藏规律分析和储层预测提供了依据。

Diagenesis and diagenetic facies of Chang 6 sandstone of Yanchang Formation in Baibao area, Ordos Basin

The sixth member of Yanchang Formation of Upper Triassic is the major exploration target zone in Baibao area, Ordos Basin, which is typical lithologic-stratigraphic reservoir. The data of the cast slice, SEM, electron probe and other tests combining with the analysis of core and sedimentary facies were applied to analyze the diagenesis of Chang 6 sandstone reservoirs. It showed that the destructive diageneses mainly include compaction-pressure solution, cementation and packing action, and that the constructive diageneses mainly include rim agglutination of chlorite and dolomite at the early stage, denudation and cataclasis. According to the association types and evolutionary sequences of the diagenesis pattern, it is concluded that the diagenetic evolution of Chang 6 sandstone has already been in stage B of the middle diagenetic stage. Based on the diagenetic evolution pattern, the diagenetic facies was studied, and it could be divided into three types, including compaction-cementation diagenetic facies association, compaction diagenetic facies association and cementation-denudation diagenetic facies association. The relationship between these diagenetic facies association and reservoir development,as well as the regional distribution were analyzed,which could provide reference for the reservoir-forming analysis and reservoir prediction of lithologic-stratigraphic reservoirs.