四川盆地武胜—潼南地区中二叠统茅口组二段下亚段白云岩薄储层成因及分布模式  

Origin and distribution model of thin dolomite reservoirs in the lower sub-member of Mao 2 Member of Middle Permian Maokou Formation in Wusheng-Tongnan area,Sichuan Basin,SW China

作　　者：谭秀成[1,2] 何如意 杨文杰 罗冰 师江波 张连进[4] 李明隆 唐宇欣 肖笛 乔占峰 TAN Xiucheng;HE Ruyi;YANG Wenjie;LUO Bing;SHI Jiangbo;ZHANG Lianjin;LI Minglong;TANG Yuxin;XIAO Di;QIAO Zhanfeng(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;CNPC Key Laboratory of Carbonate Reservoirs at Southwest Petroleum University,Chengdu 610500,China;Sinopec Exploration Company,Chengdu 610041,China;Exploration and Development Research Institute,PetroChina Southwest Oil&Gas Field Company,Chengdu 610041,China;Exploration and Development Research Institute,CNPC Daqing Oilfield Company Limited,Daqing 163712,China;PetroChina Hangzhou Research Institute of Geology,Hangzhou 310023,China)

机构地区：[1]油气藏地质及开发工程国家重点实验室(西南石油大学),成都610500 [2]中国石油集团碳酸盐岩储层重点实验室西南石油大学研究分室,成都610500 [3]中国石化勘探分公司,成都610041 [4]中国石油西南油气田公司勘探开发研究院,成都610041 [5]中国石油大庆油田有限责任公司勘探开发研究院,黑龙江大庆163712 [6]中国石油杭州地质研究院,杭州310023

出　　处：《石油勘探与开发》2025年第1期112-127,共16页Petroleum Exploration and Development

基　　金：国家自然科学基金面上项目“四川盆地早中二叠世白云岩及储层差异成因与峨眉山大火成岩省幕式响应”(42172166);国家自然科学基金中国石油联合基金重点项目“超深层碳酸盐岩孔隙形成与保持机理”(U23B20154);中国石油-西南石油大学创新联合体科技合作项目“深层/超深层碳酸盐岩天然气勘探开发基础理论与关键技术研究”(2020CX010000)。

摘　　要：通过地质、地球物理和地球化学资料的综合分析,对四川盆地武胜—潼南地区二叠系茅口组二段下亚段(简称茅二段下亚段)白云岩薄储层的特征和形成机制进行研究。结果表明:①茅二段下亚段储集岩以花斑状孔洞型白云岩、灰质白云岩或白云质灰岩为主,具有典型的早成岩期岩溶特征,岩溶系统边缘和充填物中的白云石皆具溶蚀港湾,且白云岩角砾周缘具泥晶套和环边胶结等现象,指示白云石化作用早于早成岩期岩溶。②中等盐度海水渗透回流白云石化作用是滩相薄层状白云岩的主要成因,成储关键因素为生屑滩沉积叠合渗透回流白云石化作用和早成岩期岩溶作用,局部受裂缝和热液作用改造。③白云岩孔洞型储层发育与向上变浅序列密切相关,主要发育于四级旋回的高位晚期,且白云岩规模与地层厚度密切相关,集中分布于地层厚薄转换处,其次为厚度薄值区。④结合三级旋回高位晚期地貌高地可容纳空间不足、颗粒滩向地貌低地迁移的认识,提出滩控白云岩规模储层具有“沿高环坡”的分布规律,建立了沉积期微地貌与海平面升降变化联合控滩-控云-控溶的成储模式。在此基础上,井震结合恢复茅二段下亚段沉积期古地貌并进行了储层分布预测,最新探井和试油结果验证了预测结果的准确性,这为类似地质背景下的白云岩薄储层预测提供了借鉴。This paper discusses the characteristics and formation mechanism of thin dolomite reservoirs in the lower submember of the second member of the Permian Maokou Formation(lower Mao 2 Member)in the Wusheng-Tongnan area of the Sichuan Basin,SW China,through comprehensive analysis of geological,geophysical and geochemical data.The reservoir rocks of the lower Mao 2 Member are dominated by porphyritic vuggy dolomite and calcareous dolomite or dolomitic limestone,which have typical karst characteristics of early diagenetic stage.The dolomites at the edge of the karst system and in the fillings have dissolved estuaries,and the dolomite breccia has micrite envelope and rim cement at the edge,indicating that dolomitization is earlier than the early diagenetic karstification.The shoal facies laminated dolomite is primarily formed by the seepage reflux dolomitization of moderate-salinity seawater.The key factors of reservoir formation are the bioclastic shoal deposition superimposed with seepgae reflux dolomitization and the karstification of early diagenetic stage,which are locally reformed by fractures and hydrothermal processes.The development of dolomite vuggy reservoir is closely related to the upward-shallowing sequence,and mainly occurs in the late highstand of the fourth-order cycle.Moreover,the size of dolomite is closely related to formation thickness,and it is concentrated in the formation thickness conversion area,followed by the thinner area.According to the understanding of insufficient accommodation space in the geomorphic highland and the migration of granular shoal to geomorphic lowland in the late highstand of the third-order cycle,it is proposed that the large-scale shoal-controlled dolomite reservoirs are distributed along the high annular slope,and the reservoir-forming model with shoal,dolomitization and karstification jointly controlled by the microgeomorphy and sea-level fluctuation in the sedimentary period is established.On this basis,the paleogeomorphology in the lower Mao 2 Member is restored usin

关 键 词：储层成因 沉积期地貌 颗粒滩 薄储层 白云岩 孔洞型储层 岩溶 中二叠统茅口组 四川盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]