Abstract:

According to the relations between the distribution of the formation pressure and the characteristics of gas reservoir，which is showed by pressure data measured in Feixianguan Formation，reservoir pressure genetic mechanism，evolution and the relationship of hydrocarbon accumulation of various gas pools are analyzed.Normal pressure systems always develop in reefbank complex on carbonate platform margin，most of reservoir rocks are dolostone，the main reservoir type is poretype，and gas pools are always low in methane and high in hydrogen sulfide.Abnormal high pressure or extra high pressure system appears constantly in ocean trough section or inside platform where lacks dolostone，reservoir rocks are dominated by limestone，and the main gas pool is fractured gas reservoir with high methane content，exclude or include very small amount of hydrogen sulfide.To development of pressure in fractured reservoirs and porous reservoirs，there is different evolutional mechanism，porous reservoirs experienced the stage of normal pressure in Late IndoChinese epochEarly Yanshan movement，and went through the stage of abnormal pressure which was formed by liquid hydrocarbon cracking into gas in Mid Late Yanshan movement，TSR reaction and function along with uplift shaped in Himalayan movement made the porous reservoir pressure reduce into normal stress system，and fall into a pattern with normal gas reservoir pressure.Fractured reservoirs experienced highpressure formed by hydrocarboncharging in MidLate Yanshanian movement，and experienced highpressure gas reservoir phase which was generated by structural compression function in Late Yanshanian movement，the stage of extra high pressure gas reservoir stereotyped by strong extrusion tectonics in late Himalayan.

Key words: Feixianguan Formation, carbonate rock, pressure distribution, pressureforming mechanism, structural compression, evolution, northeastern Sichuan Basin, abnormal pressure