白豹—坪庄地区延长组长6储层成岩作用研究

Diagenesis of Chang 6 reservoir of Yanchang Formation in Baibao-Pingzhuang area

鄂尔多斯盆地白豹—坪庄地区延长组长6储层是该区主要的产油层,也是典型的低孔、低渗储集层,具有粒度细、成分成熟度低、磨圆度较差、分选性较好的岩石学特征。结合铸体薄片、扫描电镜、粘土X衍射以及物性等资料,对长6储层砂岩的成岩作用进行了研究,确定其成岩作用类型主要有压实作用、压溶作用、胶结作用、交代作用及溶解作用等,其中前4种为破坏性成岩作用,最后一种为建设性成岩作用。对成岩演化序列的研究表明,长6储层砂岩的成岩阶段已达到中成岩B期的早期阶段。综合成岩作用类型的组合方式,建立了成岩演化模式,重点从成岩演化过程入手,对成岩相特征进行了细致研究,划分出了7种成岩相类型。

Chang 6 reservoir of Upper Triassic is the major oil producing zone in Baibao-Pingzhuang area, Ordos Basin. It is also typical low porosity and low permeability reservoir, with fine grain size, low compositional maturity, poor psephicity and good sorting. Based one these lithologic characteristics, the tests combining with the analysis of cast slice, SEM, X-clay minerals diffraction and property are applied to analyze the diagenesis of Chang 6 sandstone reservoirs. It shows that the diageneses mainly include compaction, pressure solution, cementation, packing action and dissolution. The first four actions are destructive diageneses, and the last one is constructive diagenesis. According to the evolutionary sequences of＇the diagenesis pattern, it is concluded that the diagenetic evolution of Chang 6 sandstone has already been in earlier stage of the middle diagenetic stage B. Based on the combination mode of the diagenetic evolution pattern, the evolutionary diagenetic pattern is studied. By emphasizing the process of the diagenetic evolution, the diagenetic facies is researched detailedly, and it is divided into seven types.