关键词: 吐哈盆地, 砂岩储集层, 热成熟度, 时间-温度指数, 埋藏方式, 深度, 孔隙度, 预测

Abstract: The main controlling factor researches about sandstone porosity of Middle-Upper Triassic reservoir in Tuha oilfield indicate that thermal maturity is closely related to sandstone porosity, and its varied range is controlled by geothermal field and buried history. The thermal maturity is comprehensively reflected by time-temperature index. The index bigger than 115 means there exists the more dense sandstone of Middle-Upper Triassic reservoir. In three burial types of the sandstone, such as gradual type, slow-early and quick-late type and quick-early and rise-late type, the slow-early and quick-late type is the most favorable for the retention of the porosity. For the first and the second burial types, the time-temperature index of sandstone is well related to the buried depth of it, from which the effective depth of the Middle-Upper Triassic reservoir in Turpan depression can be calculated to average about 4 100 meters. Based on these correlations of time-temperature index vs porosity and time-temperature index vs burial depth, the preserved depth limit of sandstone porosity and the effective reservoir can be predicted before drilling. The case study shows that this method is feasible.

Key words: Tuha basin, sandstone reservoir, thermal maturity, time-temperature index, burial mode, depth, porosity, prediction