【作者】 王若谷；

【导师】 李文厚； 赵文智；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2013， 博士

【摘要】 位于苏里格气田东二区的苏77区块和位于子洲气田北部的榆10区块均属近年来开辟的勘探新区,上古生界山西组和下石盒子组是这两个区域天然气的主力储集层,但其产能却存在着较大差异。本文从多学科理论体系入手,采用多种分析测试手段,对比研究了苏77、榆10区块上古生界山西组山23段和下石盒子组盒8下段沉积微相、储层岩石学、孔喉微观结构、成岩作用、储层物性和非均质性特征,最终探讨了储层物性主控因素,并进行了储层综合评价。鄂尔多斯盆地东北部上古生界山西组和下石盒子组物源应来自盆地北缘的阴山古陆东段,母岩主要为太古界中—高级变质岩系,并伴有大量酸性侵入岩。苏77区块和榆10区块具有一致的物质来源。山23沉积期,气候温暖湿润,距离源区较近的苏77区块发育陆相曲流河沉积,水动力较强,相对偏南的榆10区块则进入曲流河三角洲前缘相沉积,并受到海侵作用的影响,水下分流河道砂体接受了海水的改造,成分及结构成熟度均变好。盒8下沉积期,气候炎热干旱,苏77区块发育辫状河沉积,水动力十分强,榆10区块北部大面积为辫状河三角洲平原沉积,南部小范围发育辫状河三角洲前缘亚相。受海侵作用的影响,榆10区块山23段砂岩成分和结构成熟度高,以石英砂岩为主,并保留有大量残余粒间孔,填隙物含量较高,以硅质和高岭石为主,孔隙度低而渗透率高。苏77区块山23储层石英砂岩、岩屑石英砂岩和岩屑砂岩含量近等,以各种溶孔-晶间孔-粒间孔等复合型孔隙为主,填隙物含量略低,常见高岭石和硅质,孔隙度高而渗透率略低。两个区域盒8下段储层砂岩岩性相似,常见岩屑砂岩,孔隙多以溶孔-晶间孔组合为主,填隙物含量高,多为伊利石和各种碳酸盐胶结物,其中苏77区块孔隙度高而渗透率低,榆10区块孔、渗均较低。恒速压汞结果显示,研究区样品多属中-大孔微细喉型,喉道半径的大小及多种分布形态对渗透率贡献值影响较大。苏77、榆10区块山23、盒8下段储层砂岩多处于中成岩B期,不同岩性砂岩所遭受的成岩作用的强度不一致。石英砂岩表现出弱压实、中等—强胶结、弱溶蚀的特征,岩屑砂岩则表现为强压实、中等—强胶结、强溶蚀的特征,岩屑石英砂岩的成岩作用强度介于二者之间。综合考虑成岩矿物和孔隙结构的差异,划分出7种主要成岩相类型,对储层的综合评价提供一定的依据。物源区母岩的性质决定了储层砂岩的类型及其成分成熟度,物源影响着沉积体系的空间展布格局。沉积作用控制了储层的粒度、碎屑组分、砂体接触方式,并进一步影响到早期成岩作用的强弱,是控制储层物性的最主要因素。后期的成岩作用则进一步扩展了物性差异性。因此,物源、沉积和成岩作用是导致两个研究区不同层位储层差异性的主要因素。综合考虑储层的岩性、物性、孔隙结构、毛管压力曲线特征、成岩作用强度、成岩相类型及特征等方面因素,分别对苏77、榆10区块山23和盒8下段储层进行了综合分类评价,评价结果认为榆10区块山23段储层发育最好,苏77区块山23段和盒8下段仅次之,榆10区块盒8下段储层发育最差。更多还原

【Abstract】 Su77area and Yu10area, located in the east Ⅱ block of Sulige Gas Field and the northern part of Zizhou Gas Field separately, are both the new exploration aeras. The primary oil-bearing beds of the two areas are Permian Shanxi Formation and Xiashihezi Formation, but the productivities of the two areas varies markedly. In order to find out the reason leading to their differences, many systemic research includimg sedimentary facies, reservoir petrology, characteristics of micro-pore throat, diagenesis, reservoir quality and heterogeneity have been carried out comparatively, drawing support from multi-disciplinary and testing measures. Based on all the studies, the controlling factors of reservoir quality are analyzed and comprehensive reservoir evaluation is studied.The sediments’ source rocks of Upper Paleozoic Shanxi and Xiashihezi Formations in northeastern Ordos Basin are mainly derived from the YinShan ancient lands in the north, the detrital source rocks are dominated by Archean mesometamorphic to hypometamorphic rocks, accompanied by abundant acidic intrusive rocks. Through the comprehensive analysis, it is showed that the provenance directions and source rocks of Su77and Yu10area are the same.During the period of Shan23, the climate was warm and humid, Su77area, relative close to the provenance, was dominated by meandering river depositional system. At the same time, Yu10area, relative to the south, was dominated by meandering river deltaic front depositional system. Affected by the transgression, the underwater distributary deposits accepted the alteration of seawater, making the compositional and textural maturity higher. During the period of lower He8, the climate was hot and dry, braided river system with strong hydrodynamics was developed in Su77area. Meanwhile, braided river deltaic plain was developed in northern and deltaic front was developed in southern Yu10area.Affected by the transgression, the main rock type of Shan23reservoir in YulO area is quartz sandstone, plenty of primary intergranular pores are reserved in the reservoir. The content of matrix is high and the type of cements observed is mainly silica and kaolinite, causing the reservoir low in porosity and high in permeability. The characters of Shan23reservoir in Su77area are quite different, the content of quartz sandstone, lithic quartzose sandstone and lithic sandstone are nearly the same. Various types of multi-pores including dissolved pores, intercrystal pores, intergranular pores and their combinations can all be found in the reservoir. The content of matrix is lower, and kaolinite and silica are the most usual cements. The reservoir is high in porosity and a little lower in permeability. The lower He8reservoirs in the two areas showed similar characters, the main rock type was lithic quartzose sandstone with dissolved pores and intercrystal pores. The content of matrix is high, mainly illite and various kinds of carbonate cements. However the lower Hes reservoir in Su77area is high in porosity and low in permeability while the reservoir in Yu10area is both low in porosity and permeability. The result of constant-speed mercury penetration shows the main pore-throat type is mesopore-megalospore and fine throat. Contribution value of permeability is affected by the size and manifold distribution of throat radius.It is proved that the reservoirs of Shan23and lower Hes submembers in Su77and Yu10areas are mostly in the middle diagenesis phase B. The diagenesis strength of different lithologies differs from each other. The diagenesis characters of quartz sandstone proves to be weak compaction, mid-strong cementation and weak dissolution, but lithic sandstone is strong compaction, mid-strong cementation and strong dissolution, and the diagenesis character of lithic quartzose sandstone is between the other two sandstones. Considering the discrepancies of diagenetic minerals and pore structures, seven diagenesis facies can be divided, providing references for comprehensive evaluation of reservoirs.The type and compositional maturity of sand stone reservoirs are determined by the characters of source rocks, which also affect the spacial distribution partterns of the depositional system. Depositional facies, controlling the grain size, detrital sand composition and contacting types of sandbodies, influencing the strength of early diagenesis, is the chief factor affecting reservoir quality. Furthermore, the later diagenesis enlarged the differences. So deposition and diagenesis were the two main factors causing the differences of the reservoirs in the two study areas. Taking all the factors including lithology, quality, pore structure, capillary pressure curve, strength of diagenesis and diagenesis facies into consideration, the reservoirs of Shan23and lower He8submembers in Su77and Yu10area are comprehensively evaluated. The results show that the Shan23reservoir in Yu10area is the best one, Shan23and lower He8reservoir in Su77area follow next, and lower Hes reservoir in Yu10area is the worst one.更多还原