Relationships among low frequency (2Hz) electrical resistivity, porosity, clay content and permeability in reservoir sandstones

Han, Tongcheng; Best, Angus I. ORCID: https://orcid.org/0000-0001-9558-4261; Sothcott, Jeremy; North, Laurence J.; MacGregor, Lucy M.. 2015 Relationships among low frequency (2Hz) electrical resistivity, porosity, clay content and permeability in reservoir sandstones. Journal of Applied Geophysics, 112. 279-289. 10.1016/j.jappgeo.2014.12.006

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Official URL: http://dx.doi.org/10.1016/j.jappgeo.2014.12.006

Abstract/Summary

The improved interpretation of marine controlled source electromagnetic (CSEM) data requires knowledge of the inter-relationships between reservoir parameters and low frequency electrical resistivity. Hence, the electrical resistivities of 67 brine (35 g/l) saturated sandstone samples with a range of petrophysical properties (porosity from 2% to 29%, permeability from 0.0001 mD to 997.49 mD and volumetric clay content from 0 to 28%) were measured in the laboratory at a frequency of 2 Hz using a four-electrode circumferential resistivity method with an accuracy of ± 2%. The results show that sandstones with porosity higher than 9% and volumetric clay content up to 22% behave like clean sandstones and follow Archie's law for a brine concentration of 35 g/l. By contrast, at this brine salinity, sandstones with porosity less than 9% and volumetric clay content above 10% behave like shaly sandstones with non-negligible grain surface conductivity. A negative, linear correlation was found between electrical resistivity and hydraulic permeability on a logarithmic scale. We also found good agreement between our experimental results and a clay pore blocking model based on pore-filling and load-bearing clay in a sand/clay mixture, variable (non-clay) cement fraction and a shaly sandstone resistivity model. The model results indicate a general transition in shaly sandstones from clay-controlled resistivity to sand-controlled resistivity at about 9% porosity. At such high brine concentrations, no discernible clay conduction effect was observed above 9% porosity.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.jappgeo.2014.12.006
ISSN:	09269851
Additional Keywords:	Low frequency; Electrical resistivity; Reservoir sandstones; Porosity; Permeability; Clay content
Date made live:	06 Mar 2015 13:08 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/510008

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1016/j.jappgeo.2014.12.006

ISSN:

09269851

Additional Keywords:

Low frequency; Electrical resistivity; Reservoir sandstones; Porosity; Permeability; Clay content

Date made live:

06 Mar 2015 13:08 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/510008