Study On The Petroleum Potential Of Moliqing Fault Depression, Yitong Basin

After having had invested quite a lot in petroleum exploration in Yitong basin, Jilin oilfield has already obtained some exploration success. Due to the complicated geological conditions, dominated by thin interbed with low permeability and relatively low capacity, it become more and more difficult to find relatively large structural reservoir with higher capacity. Located in the south of Yitong basin, Moliqing fault depression has greater exploration potentials, although it is the one with highest exploration degree in Yitong basin. Base on qualitative analysis on the abundance, type and maturity of organic matters, we try to estimate the petroleum potentials of Moliqing fault depression through reconstructing the burial and thermal history of the basin and quantitatively restoring the hydrocarbon generating and expulsion history of its source rocks.First, evaluate the type, abundance and maturity of the organic matters by analyzing the data acquired statistically from geo-chemical analysis of core and rock cuttings samples. And then, simulate the burial history of the fault depression with Base Mod software by back stripping inversion method, restore the thermal history with EASY % Ro inversion method in the range of paleogeothermal gradient, and reconstruct the hydrocarbon generating and expulsion history of the basin with chemical kinetics combined with previously restored burial history and thermal history.As studies show that: The mudstone of Shuangyang group content abundant of favorable organic matters with high maturity, Sheling group follow it, and Yongji group is the poorest. The formation upthrow and was weathered and denuded at the end of Sheling group and the beginning of Yongji group and tend to uprise slowly after falling rapidly from Shuangyang group. The main hydrocarbon generation of Moliqing depression started from 10 Ma ago and end in nowdays. Based on burial history, thermal history and chemical kinetics and combined with hydrocarbon expulsion and aggregation coefficient, we can make out that Moliqing dominate the hydrocarbon generation with main oil generating formation of Shuangyang group and main gas generating formation of Shuangyang group and she1 section.The results of final petroleum resources evaluation show that the amount of oil and gas resources from this evaluation is respectively 2 and 20 more times of that of third evaluation, which means that there is still a great exploration potential in this fault.