Abstract:

In order to reveal the difference of hydrocarbon generation kinetics characteristics and its geologic application under different experiment conditions, two thermal simulation apparatus (open and closed systems) are employed to pyrolyze coal sample from Songliao basin. According to the relationship between experimental product yields and temperature, the kinetic models of the oil/gas generated from organic matter are calibrated. Then the kinetic parameters obtained from two experimental systems are extrapolated under the experimental heating rate and the geological heating rate, the results show that the TR (transformation ratio) increasing rate of the gas generation under closed system is slower than that under open system, the reason is that the coal sample pyrolysis to gas under open system is mainly primary cracking, but under closed system it is a common result of primary and secondary cracking. For further application, the hydrocarbon generation threshold is calculated, which combined the burial-thermal history of Xujiaweizi and the kinetic parameters obtained from two experimental systems. And the extrapolation result shows that the calculated geological time (115 Ma) corresponding to the threshold from open system is earlier than the geological time corresponding to the actual threshold (110 Ma), and the calculated geological time (92 Ma) corresponding to the threshold from closed system is later than the geological time corresponding to the actual threshold.

Key words: open system, closed system, hydrocarbon generation kinetics, hydrocarbon generation threshold, Xujiaweizi