Thermal conductivity of igneous rock cores estimated from shallow wells drilled within the Las Tres Vírgenes volcanic complex, BCS, Mexico

Abstract

In this study, the thermal properties of volcanic igneous rock cores were experimentally measured, considering them ceramic materials (that allows heat transfer conduction efficiently). Five shallow wells (with depths between 42 and 55 m) were drilled, from which different samples of volcanic core rocks (including pumice, tuff, rhyolites, basalts, and basaltic andesite) were recovered. To measure the thermal properties of these materials, the cores were cut using a diamond-tipped rock cutter and dried in an oven between 105 and 120 ◦C for approximately 12 h to remove excess lubrication fluids. The thermal properties of the rocks (thermal conductivity, thermal diffusivity, and volumetric heat capacity) were measured in twenty-one rock core samples (from five shallow wells) by a Hot Disk Thermal Constants Analyzer. The sample thermal conductivities experimental results were corrected as a function of the log-temperature depths, showing a variation based on the depth at which they were obtained. For example, the thermal conductivity for tuff is 0.73 W/mK at 5.81 m and 1.40 W/ mK at 10.20 m for the Refugio well; for pumice is 0.62 W/mK at 3.14 m and 0.52 W/mK at 11.40 m in La Reforma 1 well, and 0.52 W/mK at 3.53 m and 0.56 W/mK at 5.86 m in la Reforma 2 well; for basalt is 0.98 W/ mK at 43.53 m and 1.09 W/mK at 43.98 m in La Reforma 1 well, and 1.11 W/mK at 43.30 m in La Reforma 2 well; thermal conductivity of rhyolite is 1.42 W/mK at 55.05 m in La Reforma 2 well; and for the basalticandesite rocks, 1.32 W/mK at 43.46 m in El Azufre well, 1.09 W/mK at 6.29 m in La Fumarola well, and 1.674 W/mK at 27.88 m in Refugio Well.