Migration And Charging Of Oil And Gas In Anyue Gas Field,Sichuan Basin

In this study,based on Gas—Chromatograph(GC)and Gas Chromatograph—Mass Spectrometry(GC—MS)analyses of reservoir bitumen and source rocks from Gaoshi—Moxi region,researchs on bitumen—bitumen correlation,bitumen—source correlation,gas—source correlation have been done.it can be seen that reservoir bitumen from the three formations have similar geochemical characteristics: Normal alkanes in these bitumens have a smooth unimodal distribution of nC14~33,and the Pr/Ph all values less than 1,high abundance of the C23 tetracyclic;It has a “L” shape distribution of C27—C28—C29 steranes,the abundance of C28 regular sterane vary from 18.53%~34.91%,in distribution patterns of C27,C28,and C29 regular sterane,reservoir bitumen from the three formations aggregated in the same kind low abundance of triaromatic dinosteroids;stable carbon isotope of reservoir bitumen and fractions > — 30 ‰.Bitumen — bitumen correlation?bitumen—source correlation studies indicate that the reservoir bitumen from the three different formations belong to the same oil population,source rocks from the Qiong formation is the main source and the Deng formation source rocks also has some contribution.Composition analyses of hydrocarbon and stable carbon isotopes of gas samples from Long and Deng formation in Gaoshi—Moxi region indicate an over—matured dry gas,with carbon istopic values bigger than-30‰.The gas in Gaoshi—Moxi region may originated from both crude oil cracking and late kerogen pyrolysis.Besides,using molecular parameters(DBTs and 4—/1—MDBT)as tracing indicators,the general direction of oil charging in this region was deduced to be from west to east.Therefore,it can be predicted that the source kitchen should be on west side of Gaoshi—Moxi region,probably in the Deyang—Anyue sag.