Formation Kinetic Processes Of The Superposed Reservoir And Its Favorable Area Prediction Of C-P Coal Measures In Jiyang Depression

The research object of this work is deep C-P coal measures superposed reservoirs in Jiyang depression. Using the basic geological theory of deep oil and gas migration and accumulation, applying deep coal isothermal adsorption experiment, numerical simulation of burial, HC generation and mature and so on, Burial history, HC generation history, save history and other geological processes is restored, the accumulation mechanism of coal measures superposed reservoirs are discussed. The main research content is coal measures superposed reservoirs accumulation dynamics process. The favorable areas of coal measures superposed reservoirs are predicted by applying the reconstruction of accumulation process, building accumulation model and analyzing accumulation controlling factors. The results show that:The deep C-P coal measures in Jiyang Depression are formed in transitional facies sedimentary system. Distributary channel sandstone is developed in Shanxi Formation, and it erodes underlay coal seams. The coal seams and sandstone make up the coal measures superposed reservoirs as a special sedimentary combination. Taiyuan and Shanxi Formation are main hydrocarbon source rock which experience Indosinian, Yanshan, Himalayan and other multiphase tectonic and thermal evolution. The hydrocarbon source rock is generally experienced two secondary hydrocarbon processes. C-P coal measures source rocks experienced four periods of major hydrocarbon generation evolution processes, namely the primary hydrocarbon generation, hydrocarbon generation stagnation-gas reservoir damage, initial secondary hydrocarbon and the peak of secondary hydrocarbon. Secondary hydrocarbon threshold depth is 2100 and 3200 m in Yanshan and Himalayan epoch, and there are five favorable areas of secondary hydrocarbon generation. The deep stratum has high temperature and high pressure and the overpressure phenomenon is common. Deep CBM adsorption ability with the increase of the buried depth of coal seam is “gas bearing capacity critical depth”. Under the depth, the coal seams have significant hydrocarbon expulsion to adjacent sandstone reservoir. The gas phase in superposed reservoirs coal-formed gas include adsorbed gas in coal seams and free gas in coal seams and free gas in sandstone. Hydrocarbon expulsion powers in deep coal seam mainly include the abnormal pressure, capillary pressure difference and hydrocarbon concentration difference. Controlled by the conservation of mass and conservation of energy, the gas exceeding coal seams absorption ability can migrate to sandstone in distributary channel through erodsion surface between coal seams and sandstone. With the advent of the Himalayan peak hydrocarbon generation of coal seams, exhaust effect also accordingly increases. The hydrocarbon expulsion intensity in northern area is greater than in southern area. Exhaust process of coal seam in coal measures superposed reservoirs is of filling process in sandstone and adjustment equilibrium process between coalbed methane and coal-type gas. The favorable areas of C-P coal measures superposed reservoirs in Jiyang Depression include Linjiafan area, Jinjia area, the south slope of dongying, Chexi area and Gubei area.The study deepens the understanding of the process of Coal measures superposed reservoirs accumulation dynamics and the accumulation mechanism and provides a new way of thinking for reference in Jiyang depression of deep oil and gas exploration of C- P coal.