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为了精细、客观地揭示砂岩致密化进程差异性,明确有利储层发育模式,以苏里格气田东区上古生界二叠系致密砂岩为例,综合利用铸体薄片显微观察、孔渗测试、扫描电镜分析、包裹体均一温度测试及高压压汞测试等手段,将砂岩与泥岩作为完整的成岩体系,综合分析了砂岩成岩作用间相互影响及演化路径多样性,认为差异致密化是储层质量“因层而异”、“因砂体而异”的主控因素.研究结果表明:根据成岩演化路径将砂岩划分为8种致密化模式,早期强压实与中成岩期自生胶结物强发育形成的致密化模式砂岩具有低孔(<5%),低渗(<0.1mD),高排驱压力(>0.68 MPa)的特征,这些致密化模式共同促进了一系列独立、封闭的微成岩系统的形成.绿泥石强胶结模式通过早期孔隙流体超压与绿泥石协同保存原生孔隙,具有最高的孔隙度,一般为8.06%~11.68%,平均9.95%.绿泥石胶结+溶蚀+弱胶结模式通过溶蚀形成有效连通次生孔隙促进储层发育,孔隙度平均值7.1%,渗透性条件最好,渗透率一般为0.03~0.48mD,平均为0.12mD.这两种有利储层发育模式主要形成于厚层辫状河河床滞留、心滩砂体中—下部,中—厚层曲流河河床滞留中部、边滩砂体中部.
In order to reveal the difference of sandstone densification progressively and objectively and to clarify the favorable reservoir development model, taking the Permian tight sandstone in the Upper Paleozoic in the eastern Sulige gas field as an example, the microscopic observation of cast thin films, pore permeability test, Scanning electron microscopy (SEM), homogenization temperature of inclusions and high pressure mercury intrusion test, sandstone and mudstone are used as intact diagenetic systems. The interaction between sandstone diagenesis and the diversity of evolution path are analyzed synthetically. Difference densification is the result of reservoir quality According to the evolutionary path of diagenesis, the sandstone is divided into eight kinds of densification patterns, and the early compaction and the self-generation of the middle diagenetic period The densified sandstones formed by the strong cementation are characterized by low porosity (<5%), low permeability (<0.1mD) and high discharge pressure (> 0.68 MPa). These densification modes jointly promote a series of independent, The formation of a closed micro-diagenetic system, the strong chlorite pattern, preserves the primary porosity by the combination of early pore fluid overpressure and chlorite, with the highest porosity of 8.06% ~ 11.68% with an average of 9.95% Bonding + erosion + weak glue The formation of reservoirs by dissolution is effectively connected with secondary pores to promote the development of the reservoirs. The average porosity is 7.1% and the permeability is the best, and the permeability is generally 0.03-0.48mD with an average of 0.12mD. Formed in the thick braided river bed retention, heart-sand body - the lower part of the mid-thick stream river bed stays in central, side beach sand body central.