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分析孔隙成因类型及其控制因素,对于确定优质储层有重要意义。通过铸体薄片、扫描电镜及测录井资料分析认为,柴北缘西段古近系储层发育原生孔隙、次生孔隙和微裂缝三大类孔隙类型,原生孔隙可细分为压实残余粒间孔和胶结残余粒间孔,次生孔隙包括粒内溶孔、粒间溶孔和晶间微孔,微裂缝根据形成原因可分为压实微裂缝、溶蚀微裂缝。研究区储层孔隙类型主要发育以残余粒间孔为主的原生孔隙,其次发育粒内溶孔和粒间溶孔等次生孔隙,同时发育少量的压实微裂缝。柴北缘西段古近系储层孔隙类型主要受到沉积作用的控制,成岩作用次之,沉积作用对孔隙类型的控制体现在水动力强度的不同,水动力条件较强且成熟度较高的辫状河心滩、河床滞留及辫状河三角洲平原的分流河道、前缘水下分流河道储层砂体原生孔隙较为发育,在相同成岩作用背景下原生孔隙保留最完整,最有可能形成优质储层聚集区。
Analysis of the types of formation of pores and their controlling factors is of great significance for the determination of high-quality reservoirs. According to the analysis of casting thin slices, scanning electron microscopy (SEM) and logging data analysis, it is concluded that the Paleogene reservoirs in the northern part of the northern Qaidam Basin have three types of primary pores, secondary pores and micro-cracks. The primary pores can be subdivided into compacted residual particles Intergranular and cemented residual intergranular pores, secondary pores include intragranular dissolved pores, intergranular dissolved pores and intergranular micro-pores, micro-cracks can be divided into compaction microcracks, dissolution of micro-cracks according to the formation causes. In the study area, the pore types of the reservoirs mainly develop primary pores with residual intergranular pores, followed by the development of secondary pores such as intragranular dissolved pores and intergranular dissolved pores, and a small amount of compacted microcracks. The pore types of Paleogene reservoirs in the western part of northern Qaidam Basin are mainly controlled by sedimentation, followed by diagenesis. The control of pore types by sedimentation is manifested in different hydrodynamic strength, strong hydrodynamic conditions and high maturity braid Shaped river heart beach, river bed retention and braided river delta plain. The primary pores of the sand bodies in the leading edge submarine distributary channel reservoir are well developed. Under the same diagenesis background, the primary porosity is the most intact and most likely to form a high-quality reservoir Layer gathering area.