Temperature effects on the joint elastic-electrical properties of Berea sandstones

Joint interpretation of seismic and electrical survey data can help to better characterize the subsurface. However, the key to the successful joint interpretation is to understand the correlations between the elastic and electrical properties (i.e., the joint elastic-electrical properties) of the underground rocks. This work aims to investigate the effects of temperature on the joint elastic-electrical properties of porous rocks by simultaneously measuring the P-wave velocity, electrical conductivity and porosity of five brine saturated Berea sandstones as a function of varying temperature from 25 °C to 140 °C. We find that velocity first increases and then decreases with increasing electrical conductivity with implicitly increasing temperature. We further find that the variation of the temperature dependent joint elastic-electrical properties is determined by the dependence of velocity on temperature with a local maximum, because electrical conductivity shows strong linear increase with increasing temperature. Analyses of the experimental results illustrate that the observed variation of velocity with temperature is the combined and competitive result of the temperature-induced variations in the pore aspect ratio that quantitatively characterizes the pore structure, the properties of brine that fully saturates the samples, and the porosity of the samples, with their importance in descending order. The results reveal how the elastic velocity in Berea sandstones is affected by temperature, which in-turn provides insights into the effects of temperature on the joint elastic-electrical properties of Berea sandstones that will help to improve the joint interpretation of seismic and electrical survey data to better characterize the petroleum and geothermal reservoirs.