[Objective]China's oil and gas exploration is advancing towards the field of shale oil and gas.Over-pressure is commonly developed in organic shale,and the lack of prediction methods for shale pore pressure re-stricts the research on shale oil and gas.[Methods]This article analyses the physical response characteristics of rock to hydrocarbon generation,pressurization and disequilibrium compaction.Based on density and sound velocity data,the differential responses of hydrocarbon generation pressurization and disequilibrium compaction pressuriza-tion were analysed.The hydrocarbon generation pressurization amount is calculated using sound velocity and densi-ty,and the disequilibrium compaction is calculated using the density data.Finally,the sound velocity rebound method was established.This article selects the Bodong Depression,which has superior hydrocarbon generation conditions,as a case study.First,comprehensive mudstone compaction curves,loading-unloading curves,and sound velocity-density diagrams are used to comprehensively identify the cause of overpressure.Then,the sound velocity rebound method is used to quantitatively calculate the pressure increase and formation pore pressure of a single well under compaction and hydrocarbon generation,and the results are compared with those of numerical simulations and conventional calculation methods.[Results]Taking the LD21-A well as an example,shale over-pressure is caused by a combination of hydrocarbon generation and disequilibrium compaction.The pressure predic-tion results show that the overpressure of nonsource rock layers is contributed by the disequilibrium compaction.The overpressure of the source rock formation is contributed by hydrocarbon generation and disequilibrium compac-tion,with hydrocarbon generation pressurization mainly distributed between 5 MPa and 15 MPa(accounting for ap-proximately 35％to 65％),and the measured pressure point hydrocarbon generation pressurization is 11.09 MPa(accounting for 45％).[Conclusion]This new method is vital of importance for the research of both shale and conventional oil and gas fields.
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