Turpan - Hami Basin, Basin Analysis

The thesis represents the principle that the structural evolution of oil and gas-bearing basin control the oil and gas, the study of oil and gas-bearing basin must be systematic, dynamic and comprehensive. Based on the preceding statement we made a systematic study on the geological history (include burial history and subside history) and thermal history of the basin by means of computer modeling and multi-testing methods.The erosion thickness in Late Indo-China movement, Middle-Late Yanshan-ian movement and Late Himalayan movement has been calculated. The erosion in Late Indo-China movement showed the state of belts in direction of south to north. Middle-Late Yanshanian movement has the highest erosion thickness, and the erosion in east and north part of Turpan sag is stronger than that in the middle part. In Late Himalayan epoch, the erosion is stronger in the north edge, the east part of Taibei depression and Liaodun uplift, and is weaker in the middle part of Toksum depression, Shengnan structural belt-Pubei structural belt-Shengbei structural belt and Qiuling structural belt.The study results proved that the different part of basin underwent different structural history, subside history, burial history and thermal history, which induced different petroleum evolution. In Permian, the sediment and subsidence center is in the north edge of Turpan sag (Taerlang to Zhaobishan), in Zhaobishan and Takequan symon in triassic, in Taibei depression in Jurassic. The geothermal gradients in Early Permian-Middle Permian are in range of 4.06-4.86℃/100m. From Late Permian to Jurassic, the geothermal gradients in the west part of Taibei depression are in range of 3.03-3.85℃/100m, 2.25-3.72℃/100m in the middle part, 3.76-3.86℃/100m in the east part, 3.00℃/100m in Tainan depression, and 2.98-3.58℃/100m in Toksum depression respectively. That indicates the geothermal temperature is higher in the past than that in the present, higher in the east than that in the west in Turpan-Hami Basin.There are three main stages of petroleum migration and accumulation: late Indo-China epoch, early to middle Yanshanian epoch and late Himalayan epoch. The thermal events of Indo-China movement and Early Yanshanian movement have great effects on the maturation of source rock in Turpan-Hami Basin. The analysis indicates the most advantaged oil and gas concentration area is in the Middle of Taibei depression with its surround areas because Taibei depression has been developed continuously and stably after Permian, and it is the sediment and subsidence center in Turpan-Hami Basin, in which deep lake and multi source rock developed with large thickness at depths and appropriate thermal evolution, and where sandstones with fairly good physical quality extensively distributed and strongly superimposed, superior composing of source rock, reservoir, caprock were developed here as well.