Abstract

The objective of this model is to establish a geological foundation for pore pressure prediction (PPP) rather than using algorithms alone. This will eliminate some of the common subsurface pressure analysis pitfalls and avert possible drilling hazards.

This approach divides the previously so-called normally pressured upper section into two zones: hydrostatic and compaction hydrodynamic. Consequently, data in the hydrodynamic section is used to establish the compaction trend and not the entire section above the top of geopressure. The section below the top of geopressure is divided into transition and geopressured (overpressure) zones. This method calculates the compaction trend, rather than graphically displaying it for calibration purposes. Moreover, it extrapolates the predicted effective stress values below the top of geopressure for calculations.

PPP before drilling using seismic velocity and offset wells is a crucial endeavor for wildcat testing. Calibration of the PPP model takes place during and post-drilling using petrophysical properties and drilling events to fine-tune the algorithm constants and exponents that will be utilized for any future wildcat predictions in the same basin.