History of natural gas accumulation in Leshan-Longnyusi Sinian paleo-uplift in the Sichuan Basin was studied with chemical kinetic methods of gas generation and isotopic fractionation.The results show that:①Gaoshiti-Moxi gas bearing structure is an inherited uplift which is conducive to efficient accumulation of natural gas.The natural gas generated since 191 Ma mainly gathered in the Sinian Dengying Formation

while that generated earlier didn't accumulate or dissipated after accumulation.The gas accumulation participation rate is about 79%.②The Ziyang structural trap gradually evolved into a tectonic slope of Weiyuan trap during the Yanshan tectonic movement.The remaining non-pyrolysed crude oil migrated to the new structural high-Weiyuan trap and continued to pyrolyse there during the tectonic movement.So Ziyang and Weiyuan gas fields gather the natural gas generated before and after structural adjustment(106-104 Ma)

respectively.③Weiyuan structural trap captured limited pyrolysis gas due to its late formation

and its gas accumulation participation rate is about 51%

which is lower than that in Gaoshiti-Moxi area.④Much natural gas in Ziyang paleo-uplift was lost during Ziyang-Weiyuan tectonic inversion.Although the ending of gas generation in Gaoshiti-Moxi area is 90 Ma earlier than that in Ziyang-Weiyuan area

which is not conducive to the preservation

its gas reservoir fullness is higher than the later area.