混合沉积物成岩作用及孔隙演化差异性——以川西北部上二叠统吴家坪组为例  

The Difference of Diagenesis and Pore Evolution of Mixed Sediments:A case study of the Upper Permian Wujiaping Formation in northwestern Sichuan

作　　者：孙志昀 屈海洲[3,4,5] 李荣容 邹兵 胡欣 张云峰[3,5] 曾琪[2] 何仕鹏[2] 张兴宇[3] 刘茂瑶 SUN ZhiYun;QU HaiZhou;LI RongRong;ZOU Bing;HU Xin;ZHANG YunFeng;ZENG Qi;HE ShiPeng;ZHANG XingYu;LIU MaoYao(Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;Northwest Sichuan Gas Mine of PetroChina Southwest Oil and Gas Field Company,Jiangyou,Sichuan 621700,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China;Research Branch of Southwest Petroleum University,PetroChina Key Laboratory of Carbonate Reservoir,Chengdu 610500,China)

机构地区：[1]成都理工大学沉积地质研究院,成都610059 [2]中国石油西南油气田分公司川西北气矿,四川江油621700 [3]西南石油大学地球科学与技术学院,成都610500 [4]北京大学地球与空间科学学院,北京100871 [5]中石油碳酸盐岩储层重点实验室西南石油大学研究分室,成都610500

出　　处：《沉积学报》2025年第2期653-667,共15页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41702163,41702122);中国石油—西南石油大学创新联合体科技合作项目(2020CX010301)。

摘　　要：【目的】四川盆地西北部上二叠统吴家坪组的典型“混合沉积物”显示出巨大的油气勘探潜力,但其成岩作用及孔隙演化等方面的研究相对薄弱。【方法】通过野外剖面、岩心、薄片、阴极发光及地化分析测试等资料,研究了四川盆地西北部上二叠统吴家坪组的岩石学特征以及各岩性之间的成岩作用及孔隙演化的差异性。【结果】川西北部吴家坪组发育四大岩类及多种岩性,但以碳酸盐岩为主,吴一段—吴三段均发育;火山碎屑岩主要发育于双探1井区的吴二段中部,硅质岩主要以薄层状产出于吴一段下部—吴二段中部;碎屑岩以页(泥)岩为主,分布在吴一段底部,孔隙不发育。各岩类所经历的溶蚀作用、交代作用有明显差异。溶蚀作用在不同岩性中的表现形式及强弱不同,碳酸盐岩最发育且以颗粒/晶粒之间的溶蚀最常见,火山碎屑岩次之,硅质岩的溶蚀最弱,仅见于未被硅化的碳酸盐组分的溶蚀。交代作用在不同岩性有多种类型:碳酸盐岩常见白云石化、硅化作用;火山碎屑岩为脱玻化作用,硅质岩则是硅化作用及少量白云石化作用等。有利于各岩类孔隙发育的关键成岩阶段和作用不同:碳酸盐岩主要发育的粒间/晶间溶孔及裂缝,受同生阶段的大气水溶蚀、蒸发海水的白云石化及埋藏环境的溶蚀、白云石化、构造破裂等作用控制,火山碎屑岩主要为早成岩阶段的脱玻化形成的粒间收缩孔,而硅质岩孔隙发育最弱,主要受同生阶段大气水溶蚀残余的碳酸盐组分、构造破裂形成的裂缝及其溶蚀作用等控制。【结论】混合沉积形成了组分各异的不同岩性,各成岩阶段的溶蚀作用、白云石化作用、构造破裂等对其影响程度不同,进而控制了孔隙发育程度和演化的差异性。[Objective]The typical"mixed sediments"of the Wujiapingian age of Permian in the northwest of Sichuan Basin exhibits great potential exploration,but the research on its diagenesis and pore evolution is relatively weak[.Methods]Based on the data of field profile,core,thin section,cathodoluminescence and geochemical analysis,the petrological characteristics,diagenesis and pore evolution of the Upper Permian Wujiaping Formation in the northwest of Sichuan Basin are studied[.Results]The Wujiaping Formation in the northwest of Sichuan develops four major rocks and diverse lithology,but mainly carbonate rocks,and the First to Third members of Wujiaping Formation are developed.Volcanic clastic rocks are mainly developed in the middle of Wu2 member in well Shuangtan 1 area,and siliceous rocks are mainly produced in thin layers from the lower part of Wu1 member to the middle part of Wu2 member.The clastic rocks are mainly shale(mudstone),which are distributed at the bottom of the First member of Wujiaping Formation,with undeveloped pores.The dissolution and metasomatism experienced by various rocks are obviously different.The manifestation and intensity of dissolution in different lithology are different.Carbonate rocks are the most developed and the dissolution between grains/crystalline grain is the most common,followed by pyroclastic rocks,and the dissolution of siliceous rocks is the weakest,which is only seen in the dissolution of the non-silicified carbonate components.There are many types of metasomatism in different lithology:dolomitization and silicification are common in carbonate rocks;Pyroclastic rocks are devitrification,while siliceous rocks are silicification and a small amount of dolomitization.The key diagenetic stages and functions conducive to the development of pores in various rocks are different:the interparticle/intergranular dissolved pores and fractures mainly developed in carbonate rocks are controlled by the dissolution of meteoric water at the contemporaneous stage,the dolomitization of evapora

关 键 词：孔隙演化 成岩作用 差异性 混合沉积 吴家坪组 川西北部 

分 类 号：P618.13[天文地球—矿床学]