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Based on a conceptual model of hydrocarbon microseepage,a macro-sized experimental equipment used the matched mixtures of cement and quartz sand as simulated caprock and its overlying strata is first set up to simulate the processes of hydrocarbon microseepage and its near-surface expressions.The results of the simulation experiments suggest that simulated caprock and its overlying strata have a certain sealed capability;hydrocarbon microseepage is dominated by the pressure of point gas source,and temperature plays only a subordinate role;on the path of hydrocarbon microseepage,the distribution of hydrocarbon concentration is fan-shaped;differential adsorption of alkanes by the simulated caprock and its overlying strata results in the occurrence of a chromatographic effect.Different migrating patterns within simulated caprock are shown by the ratio of i-butane to n-butane.The concentration of hydrocarbon in the surface soil has good correspondence with the pressure of point gas source.These simulation results are significant to further study of the mechanism of anomalies recovered in surface geochemistry exploration.
Based on a conceptual model of hydrocarbon microseepage, a macro-sized experimental equipment used the matched mixtures of cement and quartz sand as simulated caprock and its overlying strata is first set up to simulate the processes of hydrocarbon microseepage and its near-surface expressions. results of the simulation experiments suggest that simulated caprock and its overlying strata have a certain sealed capability; hydrocarbon microseepage is dominated by the pressure of point gas source, and temperature plays only only a subordinate role; on the path of hydrocarbon microseepage, the distribution of hydrocarbon differential adsorption of alkanes by the simulated caprock and its overlying strata results in the occurrence of a chromatographic effect. Different migrating patterns within simulated caprock are shown by the ratio of i-butane to n-butane. The concentration of hydrocarbon in the surface soil has good correspondence with the pressure of point gas source. These simulation results are significant to further study of the mechanism of anomalies recovered in surface geochemistry exploration.