Abstract:

Based on bulk laboratory results of cast thin section, scanning electron microscope, X-ray diffraction, physical property analysis, particle size analysis, cathodoluminescence, inclusions, the characteristics of diagenesis and pore evolution of Jurassic sandstone reservoir in southeastern Tarim Basin were systematically studied in this paper. The result shows that the rock type of Jurassic reservoir in southeastern Tarim Basin is mainly composed of feldspathic lithic sandstone, lithic arkose and lithic sandstone, with low compositional maturity and low textural maturity. It is a typical low-porosity and lowpermeability reservoir. This sandstone reservoir went through strong compaction and cementation, which are mainly responsible for losing porosity. The dissolution and fissure are generally poor, but they are extremely uneven and generated a significant contribution to the improvement of reservoir properties in local development layers. The reservoir is now in the A period of middle diagenesis stage. By using physical property analysis, cast thin section and related theories to make quantitative analysis, the result shows that initial porosity of Jurassic sandstone reservoir is 28.5% to 36.2% in southeastern Tarim Basin; 9.5% to 17.0% of porosity is lost due to the early stage compaction; the cementation causes 12.6%of porosity to loss; the dissolution adds 1.5% of porosity. Thus those various factors finally cause the current reservoir porosity to be 3% to 14% with average value of 7.9%.