镇泾地区东北部长81^2低渗透碎屑岩储层成岩演化及致密化成因

Diagenetic Evolution and Densification Genesis of the Tight-reservoir in Chang-81^2 Member,Northeastern Part of Zhenjing Area

为了明确镇泾地区东北部低渗透储层特征,构建其成岩演化过程并剖析储层致密化成因,本次综合运用岩心观察、铸体薄片鉴定、黏土矿物X射线衍射分析、扫描电镜、阴极发光及岩石热解等测试分析方法,对红河油田红河12井区长81^2储层进行了详细研究。研究结果表明,长81^2主要为中—细粒岩屑长石砂岩和长石岩屑砂岩,孔隙度平均为7.2%,渗透率平均为0.246 mD。长81^2砂岩目前处于中成岩阶段A期。孔隙度随着成岩时间最后稳定在10%以下,侏罗纪末期和白垩纪末期—古近纪有所升高。机械压实作用平均损孔率高达54.36%,胶结作用平均损孔率约为41.45%,溶蚀作用平均增孔率仅为4.13%。以上认识对盆地优质储层预测及致密油开发选区具有重要的指导意义。

In order to clarify the characteristics of low-permeability reservoirs in the northeastern part of Zhenjing area,construct its diagenetic evolution process and analyze the reservoir densification genesis,Chang-81^2 reservoirs in Honghe 12 well area of Honghe oilfield were studied in detail by using core observation,casting thin section identification,clay mineral X-ray diffraction analysis,scanning electron microscopy,cathodoluminescence,rock pyrolysis etc.The results show that Chang-81^2 is mainly composed of medium-fine lithic arkose and feldspathic lithic sandstone,with an average porosity of 7.2%and an average permeability of 0.246 mD.Chang-81^2sandstone is currently in phase A of the middle diagenetic stage.Porosity stabilized below 10%with diagenetic events,and the porosity of the Paleogene in the late Jurassic and Late Cretaceous period increased.The mechanical compaction caused the average damage rate to be as high as 54.36%;the average damage rate of cementation was about 41.45%;the average porosity of dissolution was only 4.13%.The above knowledge has important guiding significance for the prediction of high-quality reservoir and the selection of tight oil development in the basin.