【作者】 尚婷；

【导师】 陈刚；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2012， 博士

【摘要】 利用岩心观察、铸体薄片鉴定、扫描电镜、X一射线衍射分析、包裹体测温、高压压汞、恒速压汞及成分分析等多种分析测试手段,系统研究储层的岩石学特征、成岩作用特征、微观孔隙特征,根据这些特征研究储层成岩演化历史,不仅具有重要的理论价值,而且对油气勘探部署和有利勘探目标的选择具有重要的实际指导意义。本文通过对鄂尔多斯盆地长8储层成岩作用、孔隙结构特征、物性特征等方面的综合研究认为：研究区延长组长8砂岩的结构成熟度高和成分成熟度较低,以细粒岩屑长石砂岩和长石岩屑砂岩为主,填隙物分布不均匀,以碳酸盐、粘土矿物、长英质次生加大为主,及少量的铁质胶结物。储层经历的成岩作用类型主要有压实作用、胶结作用、溶解作用和破裂作用。成岩演化阶段主要为中成岩的A期的晚期至B期,具有如下成岩序列：早期压实作用→绿泥石膜→早期方解石沉淀→有机酸流体进入→长石、岩屑、早期方解石溶蚀→自生高岭石形成、钠长石胶结、硅质胶结→伊/蒙混层(和绿/蒙混层)→烃类侵位→晚期铁方解石胶结→铁白云石胶结→伊利石。根据沉积及成岩作用的特征划分了储层的成岩相。储集孔隙以原生粒间孔隙为主,各种次生孔隙的长石溶孔、岩屑溶孔次之,另外还含有少量的晶间微孔；次生孔隙主要是成岩晚期阶段有机酸对长石等硅酸盐矿物、岩屑以及碳酸盐矿物的溶蚀造成的。孔隙组合类型中,以溶孔-粒间孔和微孔为主,其次为复合孔、粒间孔、粒间孔-溶孔、溶孔。研究区物性特征研究表明,本区孔隙度主要集中在6%～9%之间,渗透率大多介于0.1～1.5×10-3μm2范围之内,砂岩储层非均质性较强,为低孔、低渗储层。储层物性受孔隙发育程度、孔喉大小及之间的连通程度的影响。本区砂岩在成岩埋藏过程中,除沉积作用对储层物性有一定的影响之外,沉积作用中的压实及胶结作用是降低储层储集性能的主要因素,而溶解作用产生的大量长石溶孔等次生孔隙是提高储层储集性能的主控因素。砂岩储层性质主要受沉积相、成岩作用与成岩相等因素的共同控制。位于碳酸盐+水云母胶结相、高岭石+水云母胶结相之间的绿泥石膜+溶蚀相、绿泥石膜相是发育优质储层的良好成岩相带,而高岭石胶结相也可形成具有一定储集性能的储层。而储层中微裂缝存在,不仅使砂岩中的各种孔隙连通,提高了砂岩的储集性能,同时也充当了油气运移的输导管的作用。更多还原

【Abstract】 This paper goes on to research and discuss the characteristics of petrology, microscopic reservoir characteristics, diagenesis and reservoir physical properties. In this process,this paper analyses this points by means of methods under the guidance of sedimentology, reservoir sedimentology and oil geology. The methods include the detailed description and observation of drilling cores, and observation of thin-section of the cast, measurement of homogeneous temperature for inclusions, analyses of X-ray diffraction, cathode luminescence image, electron scan microscope, and capillary pressure. After the comprehensive research of reservoir, It is of important theoretical value and guiding significance of exploration arrangement for oil and natural gas. After the comprehensive research of reservoir, the paper holds that:The componential and textural maturities of the sandstone in Yanchang formation is lower and lithological types are mostly fine-grained arkose, which the interstitial matter is widespread but not uniform distribution. The type of cements obsedved including carbonate, clay minerals, feldspar overgrowths, and a few laumonite, ferruginous cement. Diagenesis types include compaction, cementation, metasomatism, dissolution and fraction. The sandstones have experienced a diagenetic evolution from early diagenetic phase to later diagenetic phase. The dianenetic sequence being as follows:mechanic compaction→authigenic clay rim (chlorite)→(early diagenesis) carbonnate cementation→organic acid fluid injected→feldspar, detritus and carbonate dissolution→autogenous kaolinite formation,quartz overgrowths→illite montmorillonite mixing layer (or chlorite/montmorillonite mixing layer)→hydrocarbon emplacement→(later diagenesis) Iron calcite precipitation→Dolomite filling and metasomasis clastic part According to the characteristics of diagenesis the lithogenous phase is made. The authigenic clay rim (chlorite) and feldspar dissolution diagenetic phase is considered as advantage diagenetic phase.Pore spaces always occur as the combination form, and are mainly of the primary intergranular pores. The secondary dissolution pore takes a second place. The secondary pores of the sandstones were formed by the dissolution of the alumino silicate, tuffaceous interstitial material and carbonate minerals effect by the carbonic acid and organic acid produced in late diagenesis stage.The Pore assemblage types include Dissolution pore-Intergranular pore, micropore.The reservoir physical properties show that the porosity value is from6%to9%, the permeability value is from0.1×10-3μm to1.5×10-3μm.The reservoir is characterized by low porosity and low permeability and heterogeneity is very strong. Compared with other regions of Orods basin, the quality of reservoir is more densify.High-quality sandstone reservoirs are common controlled by material source and mother rock properties, diagenesis and diagenetical facies. The chlorite+dissolution pore facies, and chlorite facies that distributing between the carbonnate cementation+hydromica facies and kaolinite+hydromica facies are the most profitable diagenetic zones for developing high-quality reservoirs. Micro-fractures on one hand make the pores connect, improve the reservoir quality of the sandstones. On the other hand, act as the role that transporting petroleum.更多还原