Pore characterization and clay bound water assessment in shale with a combination of NMR and low-pressure nitrogen gas adsorption
MetadataShow full item record
© 2018 Elsevier B.V. Pore size distribution (PSD) and the volume of clay bound water (CBW) are crucial parameters for gas shale reservoirs formation evaluation. Low-field nuclear magnetic resonance (LF-NMR) has been extensively applied to characterize petrophysical properties of reservoirs. However, limited understanding remains for unconventional shales. Defining NMR T 2 cutoff to differentiate CBW from free water is a challenge in shales since conventional approach, such as using centrifuge, is not feasible to completely remove free water in tight shales. Thermal treatment is therefore suggested for further extraction of movable pore water, however, the influence of temperature on nanoscale pore structure and clay mineralogical composition has been underestimated in previous studies and thus requires further investigation. This paper re-defines the critical dehydration temperature for accurate PSD interpretation in Permian Carynginia shale, Western Australia to determine T 2 cutoff for CBW. By using low-pressure N 2 gas adsorption (LP-N 2 -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.
Showing items related by title, author, creator and subject.
Al Hinai, Adnan Saif Hamed; Rezaee, M. Reza (2015)Assessing shale formations is a major challenge in the oil and gas industry. The complexities are mainly due to the ultra-low permeability, the presence of a high percentage of clay, and the heterogeneity of the formation. ...
Determination of NMR T2 cut-off for clay bound water in shales: A case study of Carynginia Formation, Perth Basin, Western AustraliaTestamanti, M.; Rezaee, M. Reza (2016)Low-field Nuclear Magnetic Resonance (NMR) has proved to be a valuable tool for the petrophysical characterization of conventional reservoirs, but its effective application to unconventional reservoirs is still under ...
Prediction of sonic velocities in shale from porosity and clay fraction obtained from logs - A North Sea well case studyPervukhina, Marina; Golodoniuc, P.; Gurevich, Boris; Clennell, M.; Dewhurst, D.; Nordgård-Bolås, H. (2014)Prediction of sonic velocities in shales from well logs is important for seismic to log ties if the sonic log is absent for a shaly section, for pore pressure anomaly detection, and for data quality control. An anisotropic ...