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Simplified Green-Ampt model, imbibition-based estimates of permeability, and implications for leak-off in shale reservoirs

Citation

Tokunaga, Tetsu (2020), Simplified Green-Ampt model, imbibition-based estimates of permeability, and implications for leak-off in shale reservoirs, Dryad, Dataset, https://doi.org/10.7941/D1V63M

Abstract

Predicting water imbibition into porous materials is important in a wide variety of fields, yet is often challenging because of uncertainties in both the permeability and capillary pressure driving force. Here, this uncertainty is reduced through evaluating correlations between the permeability and the effective capillary pressure associated with the wetting front, Pc,f. These correlations allow elimination of Pc,f from the Green and Ampt equation, and concentrates all uncertainties in fluxes on the effective permeability k. Over a wide range of k and n, imbibition scales approximately with k1/3. Although Leverett k1/4 scaling for predicting Pc,f is shown to be inferior when tested with data spanning a wide range of porosities n, it nevertheless predicted imbibition fairly well. From simple imbibition measurements, both the empirical and Leverett scaling approaches allow estimates of k that have root mean-square deviations of about 1 order of magnitude relative to measurements that ranged over 10 orders of magnitude in k.

Methods

These data were largely compiled from literature sources listed in the reference section of the Supporting Information. A few data are from the author's previously unpublished laboratory measurements. Data processing is decribed in detail in the manuscript.

Funding

Office of Fossil Energy, Award: DE-AC02-05CH11231