This paper investigated the secondary hydrocarbon generation potential of the Silurian asphalt sandstone in Tarim through organic petrologic observation

geochemical analysis and simulated experiment of gold-tube pyrolysis.Observation on the organic petrologic features of asphalt sandstone samples from selected wells indicates that liquid oils also exist as another main type of organic matters in addition to solid asphalt.Analysis of total organic carbon(TOC)reveals that the Silurian asphalt sandstone with relative high value of TOC

which ranges from 0.56% to 3.46%.These studies suggest that the Silurian asphalt sandstone in Tarim Basin may have some potential of secondary hydrocarbon generation.Gold-tube pyrolysis experiments further confirm that the Silurian asphalt sandstone in Tarim can generate certain amount of hydrocarbons

mostly gaseous hydrocarbons

under intense thermal stress.The maximum gas yields of samples from Tazhong-11 well and Yuenan-1 well reach 46.80 mL/g and 41.11 mL/g respectively.Furthermore

comparative pyrolysis experiments on the original and chloroform-extracted samples reveal that the gas are mostly generated from cracking of the liquid oil in asphalt sandstone.Finally

geologic deduction is performed by using the kinetic parameters of HD-11 oil cracking.The results show that gas generation from secondary cracking is possible for the Silurian asphalt sandstone in certain zones in Tarim Basin under current burial depth.And those cracking gas may be an important sources for the gas reservoirs in the study area.