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利用铸体薄片、扫描电镜、岩石物性和压汞资料,对克拉玛依油田七中、东区克下组砾岩储层孔隙结构及影响因素进行了详细分析。研究区克下组属于中孔、中渗透储层,以粒间溶孔为主,次为原生粒间孔隙,优选出孔隙度、渗透率、均值、偏态、饱和度中值半径、最大孔喉半径、平均毛管半径、视孔喉体积比和非饱和汞孔隙体积百分数共9个能反映孔隙结构的参数,采用K-Means聚类分析方法将研究区克下组砾岩储层分为4类(Ⅰ—Ⅳ),分别代表储层孔隙结构好、较好、较差、差;储层的微观孔隙分布主要有3种类型,孔隙直径分布分别呈单模态、双模态和复模态。影响孔隙结构的因素有构造作用、沉积作用和成岩作用。构造格局决定着储层的沉积格局,进而控制了储层的孔隙结构。沉积作用的影响主要表现在岩性对储层物性的控制。压实作用造成孔隙度降低;胶结作用使孔隙结构和物性变差;溶蚀作用产生的次生孔隙使储层孔隙结构和物性得以改善;重结晶作用产生的新生自形晶矿物全充填或半充填于粒间孔隙和喉道中,使孔隙减少、喉道变窄,孔隙连通性变差;压溶作用可产生压溶缝、缝合线或溶孔,扩大了孔隙空间。
The pore structure and influence factors of conglomerate reservoirs in Kexia Formation in the 7th Middle and East Kelamayi Oilfields are analyzed in detail by using cast thin films, scanning electron microscopy, petrophysics and mercury injection data. The Kexia Formation in the study area belongs to the medium-permeability and medium-permeability reservoirs, with intergranular dissolved pores as the dominant secondary intergranular pores. The porosity, permeability, mean value, skewness, median radius of saturation, and maximum porosity Throat radius, average capillary radius, apparent pore throat volume ratio and unsaturated mercury pore volume fraction can all reflect the pore structure parameters. The K-Means cluster analysis method is used to divide the conglomerate reservoir in Kexia Formation into 4 (Ⅰ-Ⅳ), respectively, representing the pore structure of the reservoir is good, good, poor, poor; micro-pore distribution of the reservoir there are three types, pore diameter distribution were single-mode, dual mode and complex mode state. The factors affecting pore structure are tectonism, sedimentation and diagenesis. The tectonic setting determines the sedimentary pattern of the reservoir and controls the pore structure of the reservoir. The effect of sedimentation is mainly manifested in lithology control of reservoir physical properties. The compaction results in the decrease of porosity; the cementation results in the deterioration of the pore structure and physical properties; the secondary porosity produced by the dissolution improves the pore structure and physical properties of the reservoir; the new born self-crystalline mineral produced by recrystallization is fully or semi-filled In the intergranular pores and throats, the pores are reduced, the throat is narrowed, and the connectivity of the pores is deteriorated. The pressure-dissolving action can cause pressure-dissolving seams, sutures or dissolved pores to enlarge the pore space.