Abstract:

The pathways of oil and gas migration in Bachu-Maigaiti areas might consist mainly of faults, unconformity surfaces,as well as vugs,fissures and pores in reservoirs,which might have been connected with each other and constitute the delivery network of oil and gas.Among the 8 major unconformities, the T₆⁰ and T₅⁵ unconformity surfaces have been open in the whole area,the T₇⁰ and T₅⁴ unconformity surfaces have been open in the southern structural belt of Bachu uplift.Multiple tectonic movements have resulted in the opening of faults, pores,vugs and fissures,and became effective migration pathways of oil & gas.According to the dynamic theory of hydrocarbon migration and accumulation in late Caledonian-early Hercynian,the major pathway would be the pore-vug-fissure system in lower Cambrian dolomite that occurred in Awati sag and northeastern area of Bachu uplift; in late to last stage of Hercynian,the major pathway would include the boundary faults in the northeastern of Bachu uplift, T₆⁰ unconformity surface and pore-vug-fissure system in lower Cambrian;in Himalayan period, the major pathway would be the T₆⁰,T₅⁵ and T₅⁴ unconformity surfaces and the fault belt on the southern boundary of Bachu uplift that occurred mainly in the area including the Maigaiti slope and southern boundary of Bachu uplift.

Key words: pathway, mirgration, unconformity surface, fault, system, dynamic reservoiring