Thermal conductivity measurement of the synthetic samples of bottom sediments containing methane hydrates

Abstract  The experimental setup is described, which makes it possible to simulate the quartz sand samples, containing methane hydrates, and to measure their thermal conductivity, using a needle probe of constant power. The method and results of measurements at different temperatures and pressures are considered. It is established that under the P-T-conditions close to the equilibrium for methane hydrate, the measurements result in the essential overestimation of the thermal conductivity the samples, i.e., to an anomalous increase in its calculated values. This is because of the dissociation (with the heat consumption) of the part of hydrates near the needle probe under the action of its heater. It is possible to conclude that this feature (the anomalous increase in the calculated values of thermal conductivity) is certain evidence for the presence of a noticeable quantity of hydrates in the sediments. This observation offers a new possibility of utilization of the geothermal method for prospecting the subsea gas hydrate accumulations. Our conclusions are confirmed by the results of measurements in situ of the thermal conductivity of the bottom sediment of the Black Sea [Kutas et al., 2005].