The Oil-migrating Fault-transfer Structure With The Hydrocarbon Vertical Migration In The Foreland Thrust Belt

There are abundant hydrocarbon resources in the foreland thrust belt of central and western China,in recent years,the hydrocarbon exploration of foreland thrust belt continue to get new achievements and breakthroughs,but in general,the exploration activity level is relatively low because of the complex geology structure in foreland thrust belt.A large variety of different scales fractures have developed in foreland thrust belt and the deformation style is different in brittle or ductile caprock.Based on the mechanical characteristics of rock,this paper has established a method to quantitative evaluate the transition from brittle to ductile of the caprock and then further discussed the controlling of faults in different brittle ductile.Domaain on the oil and gas migration and accumulation.Combined the activity period of faults and period of hydrocarbon accumulation,we preliminary determined the oil and gas source faults of Kuqa depression.Oil and gas source faults provide preponderant migration pathway for the hydrocarbon,but there is some difference of the channel capacity in different parts of the fault.Through long-term exploration study confirmed,the frequent seismic acitivity caused by fracuture stimulate fluid migration.According to the statistics of the today's global seismic date,seismogenic area of fracture are often located in position of transfer structure developed.And the transfer structure is developed in area of stress concentration,with intense tectonic deformation there will develop plenty of fractures and further provide migration pathways for hydrocarbon.Based on the phenomenon of transfer structure has close relations with the oil and gas accumulation and distribution,we come up with the conclusion that the locations of the transfer structure on the oil and gas source faults are the superiority migration pathways of hydrocarbon.At present,the formation mechanism of fault grown is the differential movement,specific performance is segment growth and tear fault.In development process of the fault,it must accompanied with development of transfer structure and then adjusted the conservation of stress and strain within the area.According to the forming mechanism and the fault geometry characters of transfer structure,divided the transfer structure of foreland thrust belt into four types:approaching?relay ramp?transfer fault and tear fault.Systematically summarized the identification method of transfer structure in foreland basins,apply the maximum fault throw subtraction method to analysis the laws of forming and evolvement about transfer structureIntegration with the above results we can see that Oil and gas source faults is the key of large amount of oil and gas accumulation,and it is the leading passage for vertical migration of hydrocarbon.Through the relationship of the activity of earthquake and the law of fluid migration,and combine the true accumulation regulation of oil and gas,transfer structure is the preponderant migration pathway of fluid,and then we established the pattern of "oil and gas source faults-transfer structure" control the oil and gas preponderant migration pathway.