STUDY ON HYDROCARBON MIGRATION AND ACCUMULATION MODEL OF THE SUPER-DEEP MARINE PETROLEUM SYSTEM IN TARIM BASIN

Tarim Basin is rich in superdeep marine resources with good drilling results, but no breakthrough has been made in exploration. The main problem is that lack of the data of deep wells drilled in the source rock, and the process of hydrocarbon generation and expulsion and the trend of hydrocarbon migration and accumulation in the ultra-deep Marine source rock were not clearly understood, which seriously affected the evaluation of favorable hydrocarbon accumulation plays and the favorable exploration targets. Based on the evolution history of source rock, trap, and reservoir, basin simulation technology was used to reveal the evolution law of generation, movement, accumulation, and adjustment of the basin's ultra-deep petroleum system. The 1D Kerogen hydrocarbon generation kinetics simulation shows that there are four key moments in the thermal evolution of lower Cambrian source rocks: middle Caledonian, late Caledonian-early Hercynian, late Hercynian, and late Himalayan. Besides, there are three thermal evolution models in the source rocks in the lower Cambrian, namely, the continuous thermal evolution model in the depression zones, the continuous thermal evolution model in the slope zone, and the rapid thermal evolution model in the surrounding piedmont zone. The simulation results of the 2D hybrid oil-gas system showed that Caledonian and Hercynian faults were more important to the migration and accumulation of primary reservoirs in Tarim Basin, while the Himalayan faults had a great influence on the adjustment of secondary reservoirs. The flow path simulation of 3D petroleum system revealed four patterns of hydrocarbon migration and accumulation in the Cambrian system in the Tarim Basin, namely convergence in the eastern region of Bachu, diffusion in the western region of Bachu, unidirectional convergence in the northern region of Tabei, and multi-source and multi-stage convergence in the Shunbei region. It is concluded that the ultra-deep reservoir of Tarim Basin developed a binary petroleum system from source rock to trap in the Caledonian and Hercytic period. A ternary petroleum system consisting of source rock, trap, and the reservoir was developed during the Indo-Chinese Epoch. The distribution of secondary reservoirs was controlled by source rock and primary reservoir.