Abstract:

According to the comprehensive analysis of light hydrocarbon composition of condensates, carbon isotopic composition of methane and its homologues，fingerprint correlation of natural gases with absorbed gases of source rocks, assemblage features of double-cycle serquiterpenes and geologic framework, this paper demonstrates that oil and gas in most O and C-P condensate gas reservoirs mainly come from humic organic matter of C-P coal seams and are mixed with a portion of oil and gas from Paleogene. The authors analyze the characteristics of hydrocarbon generation in C-P, and suggest that gas generation is main，oil generation is subordinate，and original gas-oil ratio is more than 100Cm3/t in general within vitrinite reflectance values of 0.6% —1.3%,The basic formation conditions of O and C-P condensate gas reservoirs are both the characteristics of hydrocarbon generation in C-P coal organic matter during mature stage anp the favorable geologic conditions for oil and gas accumulation.

Key words: Condensate gas reservoir, Carbon isotope, Light hydrocarbon, Jizhong Area O: Ordovician, C: Carboniferous, P: Permian, N:Paleogence