Pore characterization and clay bound water assessment in shale with a combination of NMR and low-pressure nitrogen gas adsorption

This paper re-defines the critical dehydration temperature for accurate PSD interpretation in Permian Carynginia shale, Western Australia to determine T2 cutoff for CBW. By using low-pressure N2 gas adsorption (LP-N2-GA) in parallel with LF-NMR, we identified a striking anomalous PSD consistency for critical temperature detection and verification. Our results shows that movable pore water can be maximally removed around 80 °C (75 °C), while the sensitive clay, CBW and microstructure are well-preserved for accurate petrophysical evaluation. Clay mineral conversion would occur when temperatures are higher than 80 °C, while temperatures lower than 75 °C would induce large misinterpretations for nanopore structure. Our recommended scheme could provide a potential adaptability for the formation evaluation of Permian Carynginia shale in the downhole practices.