Indeed, this is about what MIP can do. At 400 MPa pore throat radii of about 1.8 nm get filled. This is a good value but does not resolve a large fraction of the pore space that is accessed through throats smaller 3.6 nm. And keep in mind that it is the pore throats that matter. Large pores can be connected through small throats. the lower limit of 0.2 MPa is a theoretical one. There is a certain pressure needed to fill the outer roughness of mudrocks which can be higher than 0.2 MPa, so an overestimation of the mercury accessible porosity is likely.

Regards, Andreas

Dear,

I assume mudrock a medium hard strata, then 0.2MPa is less pressure. so you can some higher pressure may be >50Mpa. As already suggested by Andreas Busch throat diameter is an important factor.

Dear Sir

I think the links below will benefit you in your search

http://downloads.hindawi.com/journals/geofluids/2018/2905141.pdf

https://researchportal.hw.ac.uk/en/publications/predicting-capillarity-of-mudrocks

http://downloads.hindawi.com/journals/geofluids/aip/2905141.pdf

Article Quantitative characterization of pore-fracture system of org...

Best Regards