Abstract:
In response to the urgent needs of national oil and gas resource evaluation, detailed exploration of mature super-basins and shale oil research, the gold-tube pyrolysis hydrocarbon generation kinetics technology has been widely applied in the study of lacustrine source rocks in recent years. To clarify the technical risks of extrapolating the gold-tube hydrocarbon generation kinetics parameters of lacustrine source rocks to geological conditions for guiding conventional and unconventional oil and gas resource evaluation and exploration, the hydrocarbon generation kinetics parameters of 23 lacustrine and oil-prone coal-measure rocksfrom four super-basins, namely the Bohai Bay, Songliao, Tarim and Junggar, were extrapolated to geological conditions and parallel gold-tube and Rock-Eval pyrolysis experiments were conducted on lacustrine source rocks. The issues of calibration, application, validation and false compensation effect of the gold-tube hydrocarbon generation kinetics parameters were discussed. 1) The oil generation kinetics parameters often show an early oil generation phenomenon at low temperatures in geological applications, which is related to the residual adsorbed hydrocarbons, the lack of temperature points in the low-temperature stage of pyrolysis, and the defects in the calibration of the kinetics parameters using the single pre-exponential factor model. 2) When calibrating the gas generation kinetics parameters using the mass or volume yield of hydrocarbons and gases, it is necessary to compare the mass or volume yield characteristics of different components (C
1, C
2-5, C
1-5, C
6+) to clarify the cracking degree of crude oil and heavy hydrocarbon gases. 3) The oil generation transformation rate curve of lacustrine source rocks in the oil generation window is steep, and the difference in geothermal fields significantly affects the calculation results of oil generation. The study of geothermal fields should be strengthened in petroleum resource evaluation. The gas generation kinetics parameters should be applied in geological terms in combination with the gas production rate data when calibrating the parameters, but overestimation of the actual gas generation volume occurs in the over-mature stage.4) Using the oil saturation index (OSI)-depth profile to validate the oil generation kinetics parameters can significantly improve the prediction accuracy of the oil generation threshold and the reliability of the assessment of the free hydrocarbons (
S1) content. 5) Different combinations of kinetics parameters of the same organic phase source rocks can predict the same reaction rate (i.e., false compensation effect) under the heating rate in the laboratory, but there will be significant deviations when extrapolated to geological conditions or in-situ conversion conditions of shale oil. It is necessary to strengthen the comparison and calibration with geological data and attempt to calibrate multiple sets of kinetics parameters with unfixed or fixed pre-exponential factors. From the perspective of oil and gas exploration applications, future efforts should focus on the research and exploration of the measurement of primary cracking components/crude oil cracking components (mass conversion rate) and the characterization of related kinetics parameters in the gold-tube system.