Research On The Pool-forming Mechanism And Models Of E₁f₄-E₂d,E₂s(!) Petroleum System In Subei Basin

With the comprehensive research methods of geology, geochemistry and geophysics, the mechanism of hydrocarbon accumulation,models of hydrocarbon accumulation and distribution law are systemically studied. On the ground of diagnosing the static elements of hydrocarbon accumulation, the dynamic process of hydrocarbon accumulation was mainly studied .Combined with the characteristics of tectonic evolution and sedimentation, it is pointed out that the fault is the primary type of conduit system, the hydrocarbon mainly migrates along the fault in vertical. Systemically analyzed the mechanism of hydrocarbon accumulation, it is considered that the hydrocarbon is main up-expulsion. Overpressure formed by undercompaction is the main dynamic of primary hydrocarbon expulsion. But high amplitude feature of undercompaction in mudstone is not present overpressure, it was caused by undercompensation. The recovery of palaeopressure demonstrated that overpressure is generally existent at the age of pool-forming. Since the effect of erosion in the last stage of E2s, most reservoirs are normal pressure now. The formation water provide driving force for secondary migration, also is the carrier of hydrocarbon. The analysis of formation water provided that Na2SO4 type of formation water has medium to high salinity is formed by blending of CaCl2 type of formation water has high salinity and NaHCO3 type of formation water has low salinity. The research on migratory pathway point that hydrocarbon closely migrates in vertical. Through the recovery of hydrocarbon generation source rocks and expulsion history, the stage of hydrocarbon accumulation is demonstrated. It is considered that there was one stage of petroleum migration and accumulation in Middle-Late E2s2.Secondary hydrocarbon generation is not happened. On the basis of division principle, E1f4-E2d,E2s(!)petroleum System in Subei Basin has eleven migration-accumulation units. Based on this, Two pool-forming models are established: migrate on vertical in fault zone and depression models. Episodic pool-forming model is proposed in fault belt. The distribution law and controlling factors of hydrocarbon were systematically summarized. It is suspected that the fault has the important effect on pool-forming process at the belt of develop fault.