摘要
Abstract
The cementation of quartz is one of the very common and important diagenetic actions in sandstone reservoirs.A thorough study of the characteristics and formation mechanism of autogenetic quartz is therefore an indispensable means in revealing the reservoir characteristics, analyzing the evolution of diagenesis, and forecasting and evaluating the reservoir.According to the formation mechanism of serrated edges and the microscopic features of quartz in Lower Shihezi Formation and underlying Shanxi Formation, the authors found two corrosions and one overgrowth, with the corrosions taking place respectively before and after the overgrowth.The dissolution of feldspar is considered to be one of the main siliceous sources on the basis of the dissolution theory of feldspar and the residual structural analysis.The distribution of authigenic minerals is characterized obviously by the gradual upward decrease of quartz, the positive correlation with authigenic calcite and kaolinite, and the negative correlation with illite.Therefore, the transformation of clay minerals is considered to be another main siliceous source.The Shanxi Formation microscopically has features of pressure dissolution.In combination with the cathodoluminescence features of the quartz, it is held that there exists the siliceous source of pressure dissolution, which, however, is not the main source.On the basis of the microscopic pressure solution in underlying Shanxi Formation and the cathodoluminescence features of quartz, the pressure solution is thought to serve as a minor siliceous source.The advection flow and the diffusion migration in the reservoir made up the main migration pattern for the silicon derived from the dissolution of feldspar and the transformation of clay minerals, whereas the silicon derived from the pressure solution migrated to pores by chemical potential between particles and pores and precipitated at the grain surface or moved in the mixed source.The change of pH resulting from the invasion of acid fluids was the main factor controlling silicon deposition, while the temperature, pressure and oil-gas filling had little effects and the wrapping action of clay minerals on the grain surface had no effects on quartz deposition.关键词
自生石英/胶结作用/杭锦旗区块/硅质来源/鄂尔多斯盆地分类
天文与地球科学
