Coupled impact of high pressure and high temperature on the elastic and electrical properties of Berea sandstones

ABSTRACT Seismic and electrical methods are frequently used to understand the earth’s interior that is usually associated with high pressure and high temperature. Therefore, knowledge of the effects of high pressure and high temperature on the elastic and electrical properties of subsurface rocks will aid the interpretation of the seismic and electrical survey data. However, the coupled impact of high pressure and high temperature on the elastic and electrical properties of sandstones remains poorly understood. To address this knowledge gap, the P-wave velocity and electrical resistivity of three brine-saturated Berea sandstone samples were measured under varying confining pressure and temperature. Confining pressure increased P-wave velocity and electrical resistivity in an exponential manner. By contrast, increasing temperature reduced P-wave velocity approximately linearly and decreased electrical resistivity more dramatically at lower temperatures, followed by a gentler reduction. The increase in velocity per unit confining pressure (in MPa) was about one order of magnitude larger than the reduction in velocity per unit temperature (in °C). Conversely, the temperature-induced reduction in resistivity was greater than the improvement in resistivity from confining pressure, although they were of the same order of magnitude. The relationships between the elastic and electrical rock properties were also established and studied in terms of their dependence on the varying pressure and temperature. These findings elucidate the coupled effects of high pressure and high temperature on the elastic and electrical properties of Berea sandstones, paving the way for improved interpretation of geophysical survey data for a better understanding of the earth’s interior.