贵州赤水地区须家河组的储集特征及其发育影响因素

RESERVOIR CHARACTERISTICS AND CONTROLLING FACTORS OFXUJIAHE FORMATION IN CHISHUI AREA, GUIZHOU

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。

With 270~500 m thick and the higher maturity in this area, the Xujiahe formation. is the fluvial clastics beds overlying on the Middle Triassic Leikoupo formation with paraunconformity. The rock of Xujiahe formation mainly includes middle to thin grain feldspar quartz sandstone, lithic quartz sandstone and feldspar lithic quartz sandstone. The channel bars and point bars are the reservoirs developed facies; the diagenesis is the main controlling factors of reservoir development, in which, the compaction and pressure solution have the important effects to reduce reservoir porosity. The cementation of the autogenic minerals is also the one of the negative factors for the reservoir development. The construction diagenesis such as corrosion has little contribution on the reservoir development. The Xujiahe formation of this area is the very low porosity and permeability reservoirs with fracture and micro pore spaces.