New Method for Studying Rock Thermal Properties by Measurements on Core Cuttings and Particles of Non-consolidated Rocks

A new technology for determination of the thermal properties (thermal conductivity, thermal diffusivity and volumetric heat capacity) of rocks using drilling rock cuttings from conventional and unconventional oil fields was developed. The technology is based on (1) fabrication of solid synthetic samples as mixture of rock cuttings with a material-filler (wax, water, air), (2) measurement of the effective thermal properties of the synthetic samples with the optical scanning technique, and (3) determination of the rock thermal properties from theoretical models of heterogeneous medium using the measurement results. Fabrication and investigations of more than 160 synthetic samples, when particles of industrial and natural materials with well-known thermal properties were used as models of rock cuttings, allowed to determine optimal parameters of the synthetic sample fabricating that include rock cutting grinding procedure, selection of a material-filler, duration and pressure of synthetic sample compression, volumetric fractions of rock cuttings and material-filler, temperature of components at pressing. Regime of non-contact optical scanning measurements of the effective thermal conductivity and volumetric heat capacity of the synthetic samples were optimized to provide a high-precision level of the thermal property measurements. Peculiarities of application of the theoretical models of the thermal properties of heterogeneous medium were established to solve the inverse problems with transformation of the measurement results for the synthetic samples into the thermal conductivity and volumetric heat capacity of rock cuttings with acceptable accuracy and precision.