Methods and system for determining formation pore pressures

A system for determining formation pore pressure in a subsurface formation of a survey region, the system comprising:

• a plurality of seismic data recording sensors positioned in the survey region at different locations and/or a well logging tool including seismic data recording sensors positioned in a well bore in the survey region;
• a blasting device positioned at each point of incidence in the survey region to generate seismic waves, which travel through subsurface earth formations;
• wherein the data recording sensors transmit seismic data and well log data to a computer system including one or more memories and at least one processor, the one or memories store the transmitted seismic data, the transmitted well log data, and instructions, and the one or more processors execute the instructions stored in the one or more memories to implement:
• S1, processing the seismic data and/or well log data to determine formation parameters selected from a formation type, a formation bulk density, a formation porosity, a formation water density, a depth, a transit time, and a gravity;
• S2, calculating a vertical stress by integrating the formation bulk density in a vertical direction of the formation;
• S3, calculating a hydrostatic pore pressure based on the formation water density, the depth, and the gravity;
• S4, calculating a normal porosity based on an initial porosity or a normal transit time based on an initial transit time, a formation compact constant, and the depth;
• S5, calculating a pore pressure;
• and
• S6, obtaining a difference between the calculated pore pressure with a measured pore pressure, when the difference is larger than a threshold value, inputting the formation compaction constant of a different value into S4 and repeating S4, S5, and S6, and when the difference is not larger than the threshold value, outputting the calculated pore pressure as the formation pore pressure.