廊固凹陷沙四段储层成岩作用与成岩阶段划分

运用岩心观察、薄片鉴定、扫描电镜、X衍射分析等技术手段,对廊固凹陷不同构造带沙四段储层岩石学特征、成岩作用特征、成岩演化序列及成岩阶段划分进行了研究。结果表明,研究区沙四段储层经历的成岩作用类型有压实作用、胶结作用、交代作用、溶解作用及杂基重结晶作用等。河西务构造带岩石组分以岩屑质长石砂岩为主,成岩作用以强烈的压实作用、硅质胶结作用及碳酸盐胶结作用为主;柳泉-曹家务构造带岩石组分以岩屑质长石砂岩为主,成岩作用以长石、岩屑等的强烈溶解作用为主;旧州-固安构造带岩石组分主要为长石质岩屑砂岩,成岩作用以压实作用以及后期的杂基重结晶作用为主,见少量的碳酸盐胶结物。不同构造带储层成岩作用演化序列存在差异。研究区沙四段储层2 640 m以上处于早成岩B期,2 640~3 400 m处于中成岩A1亚期,3 400~4 250 m处于中成岩A2亚期,4 250 m以下处于中成岩B期。

Diagenesis and diagenetic stage division of Es4 reservoir in Langgu Sag

This paper studied the petrologic feature,diagenetic characteristics,the sequence of diagenesis and diagenetic stage division of Es4 reservoir in different structural belt of Langgu Sag by using the methods of core observation,thin section identification,scanning electron microscopy analysis,X-ray diffraction analysis and so on.The results show that the reservoirs experience compaction,cementation,metasomatism,dissolution and matix recrystallition.Main rock composition in Hexiwu and Liuquan-Caojiawu structural belt is lithic arkose,however,in Jiuzhou-Guan structural belt,it is feldspathic litharenite.In each tectonic zone,the most important diagenesis is different.In Hexiwu structural belt,the diagenesises are strong compaction,siliceous cementation and carbonate cementation.The diagenesises in Liuquan-Caojiawu are strong dissolution of feldspar and debris,in Jiuzhou-Guan structural belt,they are compaction,matix recrystallition and a little carbonate cementation.The sequences of diagenesis are different in each structural belt.In study area,the Es4 reservoirs above 2,640 m have been in stage B of early diagenetic stage,2,640-3,400 m in stage A1 of middle diagenetic stage,3,400-4,250 m in stage A2 of middle diagenetic stage and under 4,250 m in stage B of middle diagenetic stage.