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济阳坳陷石炭—二叠系沉积及成岩演化
Sedimentary and Diagenetic Evolution of Permo-Carboniferous in Jiyang Depression
【作者】 张关龙;
【导师】 陈世悦;
【作者基本信息】 中国石油大学 , 矿物学、岩石学、矿床学, 2007, 博士
【摘要】 近年来的勘探实践表明,济阳坳陷石炭-二叠系具有良好的油气勘探前景。在前人勘探与研究成果的基础上,综合利用地质、地球物理和地球化学等资料,并结合华北板块南北两侧造山带构造演化,对济阳坳陷石炭-二叠系地层展布、沉积作用、成岩演化、储层特征及其控制因素进行了系统研究。研究结果表明,济阳坳陷石炭-二叠系发育陆表海滨岸环境、海陆过渡环境和陆相环境等3类沉积环境;台地-泻湖沉积体系、障壁岛-泻湖-潮坪复合沉积体系、三角洲沉积体系以及河流-湖泊复合沉积体系等4种沉积体系;泻湖相、台地相、潮坪相、障壁岛相、浅水三角洲相、曲流河相和浅水湖泊相等7种沉积相类型,发生了5~6次海侵作用(沿海侵通道,海水从南向北发展,自东向西迁移),存在陆表海滨岸聚煤模式和浅水三角洲聚煤模式等2种主要成煤模式和三角洲平原泥炭沼泽、泻湖泥炭坪、岛后泥炭坪、潮坪泥炭坪和碳酸盐台地泥炭坪等5种主要成煤环境。从晚石炭世到晚二叠世,济阳坳陷发育了陆表海环境的含煤建造、海陆过渡环境的浅水三角洲相含煤建造以及陆相环境的河湖相碎屑岩建造,物源区始终为阴山造山带东部地区,碎屑物质供应能力逐渐增强。伴随着海水逐渐退去和气候变的干燥,聚煤环境变差,氧化环境下的陆相沉积逐渐占据主导地位。周缘造山带和残留海盆的构造演化是控制该区石炭二叠纪沉积演化的主要因素。依据常规物性以及孔隙结构分析,二叠系山西组浅水三角洲砂体及下石盒子组和上石盒子组曲流河砂体为该区有效储集砂体类型,总体属于低孔低渗-特低孔特低渗型储层,储集空间类型以次生溶蚀孔隙为主。孔喉半径小、分选差、连通性差、渗流能力弱是砂体储层孔喉结构的基本特征。与山西组相比,下石盒子组和上石盒子组砂岩储层具有孔喉分布偏粗歪度、渗流能力有所增强、次生溶蚀孔隙更为发育、排驱压力大幅降低的特点。在综合分析沉积条件、成岩演化和构造作用对储层物性影响的基础上,认为控制储层的主要地质因素是沉积条件,即沉积主水道的分布特征(砂体几何形态)。最后利用孔隙度、渗透率及分维三个参数,建立了该区深层储层分类评价标准,并预测出车西、义东、罗家、孤北、王家岗、金家、高青及判参镇地区为有利勘探区,邵家和惠民凹陷南坡为较有利勘探区。
【Abstract】 Experience of exploration in recent years reveals that Permo-Carboniferous formation in Jiyang depression has good oil and gas exploring promising. Base on the data of geology, geophysics, geochemistry and the tectonic evolution history of north and south border orogenic zones of North China plate, stratigraphic distribution, sedimentation, diagenetic evolution, characteristics and controlling factors of reservoir of Permo-Carboniferous in Jiyang depression have been studied.The result show that three sedimentary environments that are epicontinental littoral environment, continental-marine environment and continental environment; four sedimentary systems that are lagoon-plateau sedimentary system, barrier land-tidal flat-lagoon sedimentary system, shallow delta sedimentary system and fluvial-lake sedimentary system; seven sedimentary facies that are lagoon, plateau, barrier land, tidal flat, shallow delta, meandering river and shallow lake occurred in Permo-Carboniferous of Jiyang depression. And five to six times marine transgressions occurred in late Carboniferous period (along the transgression passageway from south to north, then, from east to west), and two accumulating coal models that are epicontinental littoral environment and shallow delta environment, five accumulating coal environments that are delta plain peat swamp, lagoon peat flat, barrier land peat flat, tidal peat flat and carbonate plateau peat flat existed. From late Carboniferous to late Permian, Jiyang depression developed epicontinental littoral environment coal-bearing sedimentary successions, continental-marine environment shallow delta facies coal-bearing sedimentary successions and continental environments fluvial and lake facies poor coal -bearing sedimentary successions, and the provenance always lay in the east area of the Yinshan orogenic zone, the ability of providing sediments gradually strengthened. Accompanying with seawater’s fallback and climate becoming to dry, the coal-forming environment becoming poor, continental sediment of oxidizing environment gradually played a main role in sedimentary successions. The tectonic evolution history of boundary orogenic zones and remnant sea basins are the main controlling factors to all the sedimentary process.Based on the analysis of routine physical properties and pore throat structure in sandstone reservoirs in Permian of Jiyang depression, shallow delta facies sand body of Shanxi Formation and meandering river facies sand body of Shang, Xiashihezi Formation are the main efficient reservoir in this area, and the reservoir sand bodies belong to low porosity and permeability to extremely low porosity and permeability, and the main reservoir space is the secondary dissolution pores. The reservoir pore throat structure characterized by mini pore throat, poor sorting, poor connectedness and poor infiltrating ability. Comparing to Shanxi Formation, Shang, Xiashihezi Formation reservoirs have the features of skewing bold pore throat size distribution, more secondary dissolution pores, improving infiltrating ability and lower displacement pressure.On the basis of reservoir physical properties affected by sedimentary condition, diagenetic evolution and tectonic process, it can be concluded that the main geological factor to control reservoir properties is sedimentary condition, i.e. the characteristics of distributions of sedimentary main fluvial channels (geometric shape of sand body). And finally, the classification criteria of the deeply buried reservoirs are established making use of the three factors-porosity, permeability and fractal dimension. Based on above analysis, it can be forecasted that the most favorable exploration targets are the west of Chenzhen, the east of Yihezhuang, Luojia, Gubei, Wangjiagang, Jinjia, Gaoqin and Pancanzhen areas and the more favorable exploration targets are Shaojia and the south of Huimin sag areas.
【Key words】 Jiyang depression; Permo-Carboniferous; Sedimentary evolution; Marine transgression; Coal-forming pattern; Diagenetic evolution; Deeply buried reservoir;