关键词: 沉积盆地, 超压环境, 有机质热演化, 生烃作用, 超压抑制作用层次

Abstract: The effects of overpressure on organic matter (OM) maturation and hydrocarbon generation were studied by multiple-parameter measurements.The differential responses of different maturity parameters to overpressure were found.Four hierarchies of overpressure retardation on the thermal evolution of organic matter and hydrocarbon generation were recognized.1All aspects of OM maturation were retarded by overpressure.2The thermal evolution of hydrocarbons and thermal degradation of hydrogen-rich kerogens were retarded,but the thermal evolution of hydrogen-poor kerogen components was not affected by overpressure.As a result,vitrinite reflectance was not retarded.3The thermal cracking of hydrocarbon was retarded,while overpressure had little effect on thermal degradation of kerogens.4Overpressure had no detectable effect on All aspects of OM maturation.The hierarchy of overpressure retardation on the all aspects of OM maturation was the combined result of "early" overpressure,namely the overpressure began to develop when the source rock was still immature,and the protracted maintenances of closed fluid system.Any case that overpressure developed too late,or overpressure was too small to reach the threshold values,or overpressure fluid was frequently released,could give rise to the occurrence that overpressure had no detectable effect on All aspects of OM maturation.

Key words: sedimentary basin, overpressure environment, thermal evolution of organic matter, hydrocarbon generation, hierarchies of overpressure retardation