| Puguang gas reservoir is located in xuanhan county in the northeast Sichuan basin. It's on a nose-shape structure,which locates at Shuangshimiao-Puguang NE structural belt to the northeast fold-fault belt of the east of Sichuan Basin. It's the most deep buried, the most abundant and the largest gas reservoir in the northeast area of Sichuan Province. In this paper, the fluid inclusions are mainly studied, through on petrography, microscopic temperature measurement, laser Raman spectra and thermodynamic calculation discuss the reservoir fluid property, reservoir physical and chemical conditions, reservoir forming stage,accumulation time and the evolution process.hydrocarbon source rocks of Puguang gas reservoir is mainly for Permain system hydrocarbon pelite and carbonate,the second is lower Silurian black shale,the reservoirs in gas field developed in the first to third secters of the Feixianguang Formation,upper Changxing Formation,which are the Lower Triassic and Upper Permian respectively, the two seal covers:?Upper Triassic Xujiahe Formation and its upper cover which mainly comprised by continental clastic argillaceous rocks;?those gyps and salt rocks which developed in the second and fourth secter of the Jialingjiang Formation in Lower Triassic and the Leikoupo Formation in Middle Triassic,they own well reservoir and caprock.Based on the microscopic observations of Puguang gas reservoir inclusions,the results show that its inclusions have diverse types,it included aqueous inclusions?gas-liquid H2 O inclusions ? aqueous H2 O inclusions?,hydrocarbon inclusions?gas hydrocarbon inclusions ? bitumen inclusions and gas hydrocarbon inclusions containing bitumen? and hydrocarbon-aqueous inclusions.At the same time,based on the micro thermometry measurement of its inclusions, the results showed that the Puguang area reservoir inclusion homogenization temperature range of 87?249?, salinity range for 4.48%21.05% and density range for 1.031.16g/cm3.According to the inclusion of main mineral occurrence ? the types of fluid inclusions and the characteristics of inclusions in combination,the Upper Permian andLower Triassic fluid inclusions of Puguang gas reservoir can divide into three periods,respectively:the early period of diagenesis?inclusions of period I?,the early stage in the late period of diagenesis?inclusions of period II?,and the late stage in the late period of diagenesis?inclusions of period III?.In period I,it is main of the gas-liquid H2 O inclusions, the homogenization temperature range from 87 to 113?,and the peak salinity is 1719wt%wt%, average value is 18.29 wt% and it belongs to shallow buried environment;in period II,there are mounts of gas-liquid H2 O inclusions,gas hydrocarbon inclusions containing bitumen and residual bitumen inclusions,The latter two are thermal cracked from Liquid phase hydrocarbon inclusions, gas-liquid hydrocarbon inclusions,The homogenization temperature gas-liquid H2 O inclusions range from 116 to 165?, and the peak salinity is 720wt%,average value is 14.58 wt% and it belongs to middle-deep buried environment;in period III,inclusions are major for hydrocarbon inclusions,hydrocarbon-H2 O inclusions and gas-liquid H2 O inclusions,the homogenization temperature range from135 to 249?, and the peak salinity is 515%, average value is 11.38wt%,corresponding to the dry gas stage,belong to deep burial environment. From stage I to stage III,with the increase of depth and evolution, the homogenization temperature increased gradually,the salinity is with a decreasing trend. Laser Raman spectroscopy shows that the hydrocarbon inclusions contain a small amount of H2 S gas.Hydrocarbon rocks in Early jurassic,Silurian and Permian reached threshold of oil generation,it beginning unboiled oil,the inclusions types mainly are gas-liquid H2 O inclusions and aqueous H2 O inclusions,only small amounts of hydrocarbon inclusions and bitumen inclusions,they are the product of early mineralization.Hydrocarbon in early Middle Jurassic-metaphase Middle Jurassic ? Silurian and Permian reached oil-generating window,it entered the stage of a large number of oil generation,at this time,forming petroleum inclusions?aqueous hydrocarbon inclusions ? gas-liquid hydrocarbon inclusions??gas-liquid H2 O inclusions and aqueous H2 O inclusions,due the rise of temperature in middle-deep buried condition,petroleum in reservoir pore gradually thermal crack into natural gas and bitumen,on macroscopical view,residual bitumen exist in solution hole?cave?the wall of cracks,on microscopic view,in terms of a petroleum inclusion in reservoir,it also can produce gas hydrocarbon and bitumen by thermal crack.If these petroleum inclusions better closed, it will form gas hydrocarbon inclusions containing bitumen,on the contrary,it will form residual hydrocarbon inclusions; hydrocarbon rocks in late period of Middle Jurassic-LowerCretaceous reached period of high mature-postmature gas generation,the types of inclusions are aqueous H2 O inclusions?gas-liquid H2 O inclusions?gas hydrocarbon inclusions and hydrocarbon- H2 O inclusions.It's a continuous process of evolution. |
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