A time‐domain induced‐polarization method for estimating permeability in a shaly sand reservoir

Abstract

A B S T R A C TIt is known that the time-domain induced-polarization decay curve for a shaly sand reservoir depends on the pore structure of the reservoir, and this curve can be used to estimate permeability, which is a determining factor in making production decisions in the petroleum industry. Compared with NMR logging tools, induced polarization has several advantages, such as a deep depth of investigation and a high signal-to-noise ratio. The purpose of this paper is to establish an appropriate model using induced polarization to estimate the permeability. The curve can be modelled as a weighted superposition of exponential relaxations. The plot of weight versus the relaxation time constant is defined as the relaxation time spectrum.Induced-polarization decay-curve measurements were performed on 123 samples from the Daqing oilfield using a four-electrode technique. A singular-value decomposition method was used to transform the induced-polarization decay data into a spectrum. Different models to estimate the permeability were discussed. The results of the research indicate that the induced-polarization measurements greatly improve the statistical significance of permeability correlations. Compared with the traditional forms, Aφ C and AF C , the forms, AT B φ C and AT B F C , have lower error factors, where T, and F are the geometric mean time constant of the induced-polarization relaxation time spectrum, the porosity and the resistivity formation factor, respectively, and A, B and C are constants. The mean time constant is the decisive parameter in the permeability estimation and it is not completely independent of the resistivity formation factor. The additional use of the porosity and the resistivity formation factor leads to an appreciable improvement. It is concluded that this new model will make it possible to estimate the permeability of a shaly sand reservoir downhole.

Complex resistivity decomposition of the Dias's model in partition fractions applied to electrolyte salinity, clay content and hydraulic permeability determination

“…These authors produced results with an error coefficient R=3.91, while the results obtained with the modified formula had R=3.16. For permeabilities above 10 mDarcy the modified formula reached a value R=1.96, very close of the R=1.76 obtained by Tong et al (2006a).…”

Review: Some low-frequency electrical methods for subsurface characterization and monitoring in hydrogeology

“…17 Prediction of permeability k from induced polarization data. Comparison between the simplified model developed by Revil and Florsch (2010) and the data (relaxation time C 0 from timedomain induced polarization and measured gas permeability) from Tong et al (2006b, their Table 1). The predictions are accurate inside one order of magnitude over four decades without the need for free parameters.…”

Impact of changes in grain size and pore space on the hydraulic conductivity and spectral induced polarization response of sand

“…With regard to the observed electrical relaxation, a number of workers have found consistently good correlations between hydraulic conductivity and the Cole-Cole time constant for a range of geological materials (e.g., Binley et al, 2005;Kemna et al, 2005;Tong et al, 2006;Zisser et al, 2010). Pelton et al (1978) were arguably the first to illustrate the adequacy of Cole-Cole-type models (Cole and Cole, 1941) for phenomenological description of the monitored SIP responses (e.g., Vanhala, 1997;Dias, 2000).…”