Abstract:

Abstract:  The study of maturation evolution of source rocks is of great significance in evaluating the regional background of oil and gas generation. Low maturity oil shale of South Junggar was chosen as sample for thermal simulating experiment of source rocks in three different conditions, that is, without water but with variation in temperatures,  with various amount of water under the constant temperature, and with constant amount of water  under different temperatures. Based on the qualitative and quantitative testing of oil, gas, and solid residue, the changes in the phase state and hydrocarbon compositions were analyzed. The experimental result shows that in the first two kinds of  experiments, the ratios of oil generation both reached their peaks at 300 ℃, whereas the latter was higher than  the former experiment of the same temperature; in the third experiment, the oil generating reached its peak with 10 mLwater; during the stage of dry gas generation, gaseous hydrocarbon mainly came from heavy hydrocarbon cracking rather than high maturity kerogen itself. After thermal cracking at 400 ℃, the remaining ratio of oil generation decreased to its minimum being 5%; the amount of saturated hydrocarbon was high in conditions of low and extreme high temperatures, mainly composed of nalkanes. The amount of aromatic hydrocarbon, mainly composed of triaromatics and tetraaromatics, was highly variable in different temperatures, and reached its maximum at 400 ℃ and  lowered down to the minimum at  500 ℃, whereas the changes in the amount of the nonhydrocarbon and bitumen were contrary to that.