Study of the variation of thermal conductivity with water saturation using nuclear magnetic resonance

Abstract

[1] In this paper, we present a method that allows one to correct thermal conductivity measurements for the effect of water loss when extrapolating laboratory data to in situ conditions. The water loss in shales and unconsolidated rocks is a serious problem that can introduce errors in the characterization of reservoirs. For this study, we measure the thermal conductivity of four sandstones with and without clay minerals according to different water saturation levels using an optical scanner. Thermal conductivity does not decrease linearly with water saturation. At high saturation and very low saturation, thermal conductivity decreases more quickly because of spontaneous liquid displacement and capillarity effects. Apart from these two effects, thermal conductivity decreases quasi-linearly. We also notice that the samples containing clay minerals are not completely drained, and thermal conductivity reaches a minimum value. In order to fit the variation of thermal conductivity with the water saturation as a whole, we used modified models commonly presented in thermal conductivity studies: harmonic and arithmetic mean and geometric models. These models take into account different types of porosity, especially those attributable to the abundance of clay, using measurements obtained from nuclear magnetic resonance (NMR). For argillaceous sandstones, a modified arithmetic-harmonic model fits the data best. For clean quartz sandstones under low water saturation, the closest fit to the data is obtained with the modified arithmetic-harmonic model, while for high water saturation, a modified geometric mean model proves to be the best.Citation: Jorand, R., A. Fehr, A. Koch, and C. Clauser (2011), Study of the variation of thermal conductivity with water saturation using nuclear magnetic resonance,

Heat flow in vapor dominated areas of the Yellowstone Plateau Volcanic Field: Implications for the thermal budget of the Yellowstone Caldera

“…There are several models used to calculate the bulk thermal conductivity ( K b ) of porous and variably saturated rocks [ Jorand et al , 2011]. The geometric mean bulk thermal conductivity is applicable only when the constituent conductivities vary by less than one order of magnitude [ Sass et al , 1971] and is applicable mainly in rocks with water saturation >60% [ Jorand et al , 2011]. Neither of these conditions is applicable to our samples.…”

“…The calculated arithmetic mean and harmonic mean bulk thermal conductivities ( K b ) are 1.30 ± 0.21 W·m −1 ·K −1 and 1.24 ± 0.20 W·m −1 ·K −1 , respectively. Following the approach of Jorand et al [2011]we calculate a arithmetic‐harmonic mean of 1.27 ± 0.21 W·m −1 ·K −1 , which is an average of the two means. The cumulative uncertainties were calculated by propagating the errors resulting from averaging matrix thermal conductivity, porosity, and volumetric water saturation.…”

Impact of diagenesis on reservoir quality in a sedimentary geothermal play: a case study in theCooperBasin,SouthAustralia

“…Where ø is the total porosity (%), and C a constant normally used to adjust NMR logs and traditionally set at 10 in sandstones (Jorand et al, 2011). Assuming that the mobility of reservoir fluids is primarily controlled by pore sizes, a fixed T 2 value can relate directly to a pore size at or below which fluids will not move.…”

Enhanced gas recovery with CO2 sequestration: The effect of medium heterogeneity on the dispersion of supercritical CO2–CH4

“…The Berea sandstone was characterized by a unimodal distribution of T 2 relaxation whereas Donnybrook showed a broader multimodal distribution. In our previous work, large proportions of the pores in these sandstones were demonstrated to be over one micron (Honari et al, 2013) and the relatively small numbers of micro pores observed was attributed to the presence of claybound water (Jorand et al, 2011;Straley et al, 1997). The distributions of T 2 relaxation for the carbonate rocks consisted of two distinct peaks, which was consistent with the pore size distributions previously reported (Bijeljic et al, 2013a;Tanino and Blunt, 2012).…”