ANALYSIS AND CALCULATION OF HYDROCARBON ACCUMULATION HISTORY AND PALEO-FLUID POTENTIAL FIELD OF TRIASSIC RESERVOIRS IN LUNAN LOW UPLIFT OF TARIM BASIN

There are many structural tectonic cycles and active tectonic movement in the Tarim Basin, which are characterized by multi-period accumulation. Therefore, the adjustable reservoir become an important field of exploration in Tarim Basin. Based on the regional thermal evolution history and burial history, the main time of oil accumulation is determined by systematically analyzing the samples of the Triassic sandstone reservoir inclusions in the Lunnan area, and the characteristics of oil migration and paleo-fluid potential field are studied. Homogenization temperatures of associated saline inclusions show unimodal distribution, mainly ranging from 110 ℃ to 120℃. One petroleum charge episodes can be distinguished in the Triassic reservoirs of Lunnan Low Uplift, during late Himalayan orogeny (13.8~4.9Ma). The evolution of paleo-formation pressure during these three charging stages was obtained through PVT thermodynamic modeling of the fluid inclusions. The results in combination with fluid density of salt water inclusions and paleoelevation reveal the hydrocarbon migration and filling direction during the accumulation period. Combined with the distribution characteristics of the present reservoirs, it is shown that the primary reservoirs of the Lunnan Triassic has been greatly adjusted due to the new active tectonic movement.