摘要
Abstract
In order to investigate the origin and evolution of the Silurian asphaltic sandstones in Talimu Basin, the authors studied in detail the macrocharacter, microcharacter, reflectance (Ro%) and fluoroscopic character of the asphalts in the sandstones, the characteristics of the sandstones in petrology and diagenesis, diagenetic succession and diagenetic stage division by means of petrology and organic petrology. In the Silurian asphaltic sandstones from Talimu Basin, there are grayish-black—brownish-gray dry asphalts, soft asphalt and viscous crude oil. Macroscopically, there are two types of asphalt distribution, one is uniform distribution (massive), and another is non-uniform distribution (mottled, being further divided into bedding, lenticular and fracturing). Microscopically, they are classified into packing and disseminating distributions. The diagenetic succession of the sandstones is as follows: mechanical compaction (plastic deformation of grains)→ formation and conversion of clay film→ authigenic overgrowth of quartz and dissolution of aluminosilicate→ precipitation of crystal stock calcite→ pressolutional overgrowth of quartz→ conversion form calcite to ankerite→ precipitation of chlorite. The diagenetic stage can be divided into subphase A of eodiagenesis, subphase B of eodiagenesis, subphase A of telodiagenesis and subphase B of telodiagenesis. The asphalt reflectance (BRo) shows that formation of the asphalt was hardly affected by thermal action. Practically, the Silurian asphaltic sandstones were formed mainly by intense bio-degradation and the BRo value reflects the bio-degradation grade of the asphalt. Diagenesis data indicate that the Silurian asphaltic sandstones are the products of multiple fillings of hydrocarbon.关键词
塔里木盆地/志留系/沥青砂岩/岩石学/有机岩石学分类
能源科技
