掘屑による原位置岩石の有効熱伝導率の推算 第２報 掘屑・水充填層の伝熱解析および伏目地熱井における事例研究

Abstract

Heat conduction in the cuttings-water mixture beds has been analyzed using Kunii's formula. The analysis was conducted to estimate thermal conductivities of formation rocks in situ from the effective thermal conductivity of the cuttings beds which were measured at simulated geothermal conditions by a new rapid measurement method developed by the authors. As the results of numerical experiments by the analysis, it was made clear that controlling parameters for the thermal conductivity of rock martix of the cuttings estimated, λs, were the total porosity and the effective thermal conductivity of the mixture bed measured.All measurements of the effective thermal conductivity, λe, of the mixture beds of water and cuttings from SKG-11D well, Fushime geothermal field, Kagoshima pref., Japan were conducted at the natural cooling process from 200°C to room temperature as the results of the preliminary study by using fused quartz grains. The estimated values of thermal conductivity of dry cutting particles saturated with dry air, λea, of the samples from the well agreed well with the measured values of λea of the core samples from the corresponding strata within the experimental errors. The effective thermal conductivity of rocks in situ of the well at the depth from 1, 500 to 1, 900m was estimated at 3 to 4W/(m•K).