Abstract:

The controlling of fault on the tight sandstone gas migration and accumulation of the continental strata in West Sichuan depression is very apparent.  On basis of the research of the fault distribution characters，fault property，geometric characteristics，formation period，combined with the analysis of the connection of faults and sandstone，statistic of the developing wells state，the controlling factors of faulting on gas migration and accumulation are studied in detail.  The research shows that five models can be identified by the controlling of fault on the tight sandstone gas.  The first model shows that the fault growth prompted the natural gas accumulation in the tight sandstone in the deep strata of the Upper Triassic Xujiahe Formation reservoir.  The second model indicates the fault development destroyed the natural gas reservoir in the deep strata of the Upper Triassic Xujiahe Formation.  The third model means that the faults transported the deep natural gas migrating and accumulating in the shallow Jurassic tight sandstone.  The fourth model indicate the fault destroyed badly the natural gas reservoir in Jurassic tight sandstone.  The last model shows the lack of fault growth is not good for the natural gas accumula tion in the shallow Jurassic reservoir.The distance between the well and fault is also an important factou effecting the well production capcity.Different scale faults may create different gas accumulation.Scale I fault (spreads higher than 100 km)and Scale II fault (spreads higher than 10 km and lowe than 100 km)show the same regularity of medium distance between well and fault is most favorable for the gas accumulation,too far or too close is not good for gas reservoir.Scale III fault has the apparent positive controls that on the well production capacity increase with the increase of distance of well and fault.

Key words: West Sichuan depression, tight sandstone reservoir, fault, natural has migration, natural gas accumulation