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赤水地区须家河组地层平行不整合于中三叠统雷口坡组之上,主要为一套结构成熟度和成分成熟度都相对较高的河流相碎屑岩,厚度为270～500m。其岩石类型视不同层位分别以中—细粒长石石英砂岩、岩屑石英砂岩或岩屑长石石英砂岩、长石岩屑石英砂岩为主。辫状河和曲流河的心滩、边滩等沉积微相是储层发育的主要相位;成岩作用是控制本区须家河组储层发育的主要因素,其中,压实与压溶作用对破坏储集性和降低孔隙度起着重要作用,自生矿物及其胶结作用也是破坏储集性的因素之一,而建设性成岩作用如溶蚀作用对储层发育的贡献不大;受物性影响,本区砂岩主要为一套特低孔、特低渗砂岩,其储集空间以裂缝—(微)孔隙为主,储集条件较差。
The strata of Xujiahe Formation in Chishui area are unconformablely paralleled with the Leikoupo Formation of the Middle Triassic, and mainly consist of a series of fluvial clastic rocks with a relatively high degree of structural maturity and compositional maturity, with a thickness of 270-500 m. The rock types depend on different layers, mainly medium-fine feldspar quartz sandstone, cuttings quartz sandstone or lithic feldspar quartz sandstone and feldspar lithic quartz sandstone, respectively. The sedimentary microfacies of braided river and meandering river are the main phases of reservoir development. Diagenesis is the main factor that controls the development of Xujiahe formation in this area. Compaction and pressure solution Destruction of reservoirs and reduction of porosity plays an important role. Authigenic minerals and their cementation are also one of the factors that destroy reservoir property. However, constructive diagenesis, such as dissolution, has little contribution to reservoir development. The sandstone in this area is mainly a set of extra-low-porosity and ultra-low permeability sandstone. Its reservoir space is dominated by fissure- (micro) pores, and the reservoir conditions are poor.