Dear Nuwara: as you can see in the pore pressure prediction workflow image that I send to you from the excellent paper "Velocity based pore pressur eprediction—A case study at one of the Iranian southwest oilfields" by Hamidreza Soleymani and Mohamad-AliRiahi, the answer is Yes!, you can estimate the pore pressure from an acoustic (poststack) inversion instead elastic (prestack) ones.

This is because the main properties that influence in the estimation is the velocity field model that you use as input. If you have a good velocity estimation, really even you do not need any kind of inversion, nor acoustic, nor elastic. Perhaps you use just the RMS velocity from the PSTM migration. The real problem is the resolution, the vertical resolution, and the calibration of your model with well-logs.

Of course, if you have a velocity model from any kind of inversion, it means that you use the key-wells in the process, and, of course, there are a good matching between the wells and the seismic output. Acoustic inversion. Elastic inversion. No problem.

On the other hand: if you observe the workflow from the colleagues, inmediately you can put your focus not only in the left side (velocity model), but also in the right-side: density model. And, just only by elastic inversion you can recovery or estimate the density as a volume. This is the great value of the elastic inversion: you get the velocity and the density model. But remember it is so hard to get a density volume if you do not have an excelent range of angle-gathers, and also, an excelent design and acquisition seismic. It is the key problem in the projects that I have experience: I try to use the seismic for a whole range of objectives: illuminate the reservoir main fault structure at all the depths, try to do seismic sequence stratigraphy for a whole interval, and try to use the gathers for a whole sedimentary column. Think about it: a multiplicity of factors influence the seismic responses and seismic velocities.

It seems like yesterday, but it was long ago when Gardner GHF, Gardner LW and AR Gregory describe the velocity and density as a diagnostic for seismic.

Anyway: There were so many roads, searching for pore pressure estimation, again and again, but I think you can run/estimate the pore pressure estimation by elastic or by acoustic seismic inversion.

Best regards, Mario E. Sigismondi

I know this sounds simplistic, but basically you can convert velocity to pore pressure with an empirically derived function. The more data you have the better and it probably needs to be sorted by lithology, geologic age etc.

I have seen it work in young (Tertiary) sedimentary rocks, primarily sand and shale. The trend (slope) of increasing velocity with depth changes with increasing pore pressure. You can use stacking or migration velocities, but it needs to be calibrated with pressure data from wells.

Regards

Dear Mario Emilio Sigismondi, very comprehensive explanation, Mario. I have reviewed the workflow and paper that you shared with me. However, I don't have interval velocity data from stack/semblance. I only have inversed impedance section. I have made velocity and density model, both using multiatribute and neural network. Will this work out by only using these models without v interval?