Seismic pore-pressure prediction using prestack seismic inversion

A system for predicting pore pressure based on seismic data, comprising:

• a processor to execute computer-readable instructions that, in response to execution of the computer-readable instructions, cause the processor to perform operations comprising:
• obtaining seismic inversion data based in part on seismic data collected from a formation, wherein the seismic inversion data comprises seismic impedance data, and wherein the seismic impedance data comprises a P-velocity value divided by an S-velocity value;
• calculating a pore-pressure transform, wherein the pore-pressure transform comprises one or more parameters derived using measured pore pressure data, at least one upscaled sonic log, and at least one density log, wherein the pore-pressure transform comprises an objective function to reduce unphysical variations in predicted pore pressure corresponding to depth, and wherein the objective function comprises a first term and a second term;
• adjusting the pore-pressure transform for sampling bias caused by pore pressure measurements being restricted to a plurality of lithologies by accounting for a difference between upscaled seismic velocities and average sonic velocities within each of the lithologies;
• generating one or more pore pressure prediction values based on the pore-pressure transform for the lithologies and the seismic inversion data;
• and
• generating an image that shows the pore pressure versus the depth, wherein the image is based at least partially upon the one or more pore pressure prediction values.

A non-transitory computer-readable medium for predicting pore pressure based on seismic data, comprising a plurality of computer-readable instructions that, in response to execution of the computer-readable instructions by a processor, cause the processor to perform operations comprising:

• obtaining seismic inversion data based in part on seismic data collected from a formation, wherein the seismic inversion data comprises seismic impedance data, and wherein the seismic impedance data comprises a P-velocity value divided by an S-velocity value;
• calculating a pore-pressure transform, wherein the pore-pressure transform comprises one or more parameters derived using measured pore pressure data, at least one upscaled sonic log, and at least one density log, wherein the pore-pressure transform comprises an objective function to reduce unphysical variations in predicted pore pressure corresponding to depth, and wherein the objective function comprises a first term and a second term;
• adjusting the pore-pressure transform for sampling bias caused by pore pressure measurements being restricted to a plurality of lithologies by accounting for a difference between upscaled seismic velocities and average sonic velocities within each of the lithologies;
• generating one or more pore pressure prediction values based on the pore-pressure transform for the lithologies and the seismic inversion data;
• and
• generating an image that shows the pore pressure versus the depth, wherein the image is based at least partially upon the one or more pore pressure prediction values.