吴起地区马家沟组马五段岩相特征及成藏期次研究  

Study on the lithofacies characteristics and reservoir accumulation stages of Ma 5 member,Majiagou Formation in Wuqi area

作　　者：李超 杨青青 李渊 高天然 栾建建 尹帅 LI Chao;YANG Qingqing;LI Yuan;GAO Tianran;LUAN Jianjian;YIN Shuai(No.3 Gas Production Plant of Yanchang Gas Field,Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Yan’an 716000,Shaanxi,China;School of Earth Sciences and Engineering,Xi’an Shiyou University,Xi’an 710065,Shaanxi,China)

机构地区：[1]陕西延长石油(集团)有限责任公司延长气田采气三厂,陕西延安716000 [2]西安石油大学地球科学与工程学院,陕西西安710065

出　　处：《石油地质与工程》2025年第1期58-66,73,共10页Petroleum Geology and Engineering

基　　金：陕西省自然科学基础研究计划项目(2023-JC-QN-0355)资助。

摘　　要：为给深部碳酸盐岩储层天然气勘探评价提供可靠依据,以鄂尔多斯盆地吴起地区马家沟组马五段中下组合(马五_(5)亚段-马五_(10)亚段)为例,利用大量岩心、薄片、测井及构造热演化史模拟等资料,系统的开展了岩石类型、岩相特征、天然气发育特征、成藏期次等研究。结果表明,马家沟组发育以灰岩、白云岩及其过渡类灰岩为主的多旋回沉积岩性组合;其中,灰岩可细分为泥晶或砂屑泥晶灰岩、砂屑灰岩,过渡类灰岩包含云斑含云灰岩或云灰岩,白云岩分为泥晶白云岩及粉-细晶白云岩。主力产层马五_(5)亚段与马五_(4)亚段分布范围大体一致,主要分布在研究区东部,且西部大面积地层均被剥蚀。马五_(5)亚段主要发育高能浅滩及开阔台地环境下的泥粒灰岩及生物灰岩,马五4亚段主要发育云坪环境下的白云岩。马家沟组烃源岩主要发育Ⅰ、Ⅱ型及少量Ⅲ型干酪根,R_(o)值2.0%~3.0%,为高-过成熟烃源岩。区内稳定盖层包括本溪组底部铝土岩、暗色泥岩以及马五段石膏层,保存条件好。马五_(5)亚段-马五_(10)亚段天然气δ^(13)C_(1)分布于-40‰~-32‰,δ^(13)C_(2)分布范围较大,在-38‰~-22‰间,表现为煤型气及油型气的混合特征,天然气类型的分布与奥陶系马家沟组顶面层位分布有关。区内马家沟组马五段天然气成藏经历了中-晚侏罗世液态烃充注期(180~155Ma)和早白垩世天然气大量生成充注主成藏期(155~145Ma)。In order to provide reliable basis for the exploration and evaluation of natural gas in deep carbonate reservoirs,taking the middle and lower members of Majiagou Formation in Wuqi area of the Ordos Basin(M 5-M10)as an example,core,thin section,logging,and structural thermal evolution history simulation data were used to study rock types,lithofacies characteristics,natural gas development,and reservoir accumulation stages.The results show that the main rock types are limestone and dolomite rocks.Limestone can be divided into micrite,sand micritic limestone,sand clastic limestone and transitional limestone.The sand clastic limestone can be further subdivided into micritic sand clastic limestone and sparry sand clastic limestone.The transitional limestone mainly includes dolomitic spots dolomitic containning limestone and dolomitic spots dolomitic limestone.Dolomite can be divided into micrite dolomite and powder-fine dolomite.The petrographic paleogeography of the main production layers,Ma 5_(5) and Ma 5_(4) are finely delineated.The distribution of Ma 5_(5) and Ma 5_(4) is generally consistent,mainly in the eastern part,while the strata are denuded over a large area in the west.Ma5_(5) mainly develops mud-grained chert and biotite in high-energy shallow and open terrace environments,and Ma5_(4) mainly develops dolomite in a cloudy apron environment.The source rocks of Majiagou Formation in the study area are mainly kerogen types of type Ⅰ and Ⅱ,and followed by type Ⅲ,and with R_(o) ranging from 2.0% to 3.0%.The bauxite rock,dark mudstone and gypsum rock in the bottom of the Benxi Formation are stable and have good preservation conditions.The δ^(13)C_(1) distribution of gas from Ma5_(5)-Ma5_(10) ranges from -40‰ to -32‰,and the δ^(13)C_(2) distribution ranges from -38‰ to -22‰,which shows the mixed characteristics of coal type gas and oil type gas.The distribution of natural gas type is related to the distribution of the top horizon of the the Ordovician Majiagou Formation.Through structural thermal

关 键 词：鄂尔多斯盆地 马家沟组 岩相特征 烃源岩 成藏期次 

分 类 号：P631.84[天文地球—地质矿产勘探]