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根据砂岩热成熟度的概念,认为塔里木盆地古生界砂岩的孔隙度主要受控于与地热场、埋藏时间和盆地沉降方式有关的砂岩热成熟度。用热成熟度比用深度可更合理地解释砂岩孔隙度的发育特征及其成因。TTI值可综合反映热成熟程度,TTI值越大,砂岩的热成熟度越高,成岩强度越大,被保存的孔隙度越小。若已知盆地的地温梯度,可计算出预测储层的TTI值,并可用本文提出的砂岩热成熟度—孔隙度和热成熟度—深度的两个定量关系预测砂岩区域孔隙度值和有效储层的最大保存深度。应用此法预测塔里木盆地中—上志留统岩屑砂岩和下石炭统石英砂岩有效储层最大保存深度,效果良好。
According to the concept of thermal maturity of sandstone, it is considered that the porosity of Paleozoic sandstone in Tarim Basin is mainly controlled by thermal maturity of sandstone related to geothermal field, burial time and basin subsidence. The developmental characteristics and their causes of sandstone porosity can be more reasonably explained by the ratio of thermal maturity to depth. The TTI value can comprehensively reflect the degree of thermal maturity. The larger the TTI value is, the higher the thermal maturity of the sandstone is and the greater the diagenetic intensity is and the smaller the porosity is preserved. If the geothermal gradient of the basin is known, the TTI value of the predicted reservoir can be calculated, and the two quantitative relationships of the sandstone thermal maturity - porosity and thermal maturity - depth can be used to predict the sandstone porosity and effective reservoir The maximum depth of layer preservation. This method is applied to predict the maximum preserved depth of the effective reservoirs of the Middle-Upper Silurian lithic sandstone and the Lower Carboniferous quartz sandstone in the Tarim Basin, with good results.