贵州主要岩石地层热物性参数特征及影响因素分析

Thermal property parameters and influencing factor analysis of main rock strata in Guizhou province

岩石热物性是地表、地球内部温度分布及热传递研究不可缺少的参数,贵州乃至西南地区均尚未开展过系统性、区域性的岩石热物性参数研究工作。为给贵州及相邻区域开展地热、油气成藏以及岩土工程等研究工作提供依据和参考,本次采集了贵州主要地层的14种岩类,共计433件岩石样品,并进行热导率、比热容及热扩散率的测试,分析了不同岩石的热物性参数特征及影响因素。研究表明:贵州地区岩石热导率的实测平均值在1. 516±0. 264~5. 066±0. 521W/(m·K)之间,比热容的实测平均值在0. 272±0. 042~0. 603±0. 096kJ/(kg·℃)之间,热扩散系数的实测平均值在0. 752±0. 331~2. 854±0. 368mm2/s之间。区内岩石热物性与其矿物成分、结构、含水量等因素有关,其中,岩石年龄越老,热导率和热扩散系数越高;岩石的热导率和热扩散系数与高热导率矿物含量存在正相关关系,而比热容则相反;随着岩石中矿物颗粒粒度的增大,岩石热导率和热扩散系数也随之增加,而比热容与矿物颗粒粒度的关系则不明显;含水量对岩石的热物性影响较大,饱水条件下岩石的热导率比干燥条件下的热导率增加幅度在2%~17%,热扩散系数增加的幅度集中在1%~16%,而比热容则减少,减少幅度在3. 08%~21. 79%。

The thermal properties of rocks are indispensable parameters in studying surface temperature, temperature distribution and heat transfer of the Earth. However, there has been no systematic and regional research performed on thermal properties of rocks in Guizhou and even in Southwest China. In order to provide scientific support for research of geothermal, hydrocarbon accumulation and geotechnical engineering in Guizhou and its adjacent areas, this study collected a total of 433 rock samples in this area which are classified into 14 kinds of rocks to test thermal conductivity, specific heat capacity and thermal diffusivity, as well as analyze the thermal properties and influencing factors. The research shows that the measured average value of rock thermal conductivity in the Guizhou area is between 1. 516±0. 264~5. 066±0. 521W/(m·K), and the measured average value of specific heat capacity is 0. 272±0. 042~0. 603±0. 096kJ/(kg·℃). The measured average value of the thermal diffusivity is between 0. 752±0. 331~2. 854±0. 368 MJ/(m3·K). The thermal properties of rocks in the area are related to mineral composition, structure, water content and other factors. The older the rock age, the higher the thermal conductivity and thermal diffusivity. The thermal conductivity and thermal diffusivity of rock are positively related to high thermal conductivity mineral content, but negatively to heat capacity. With increasing of the particle sizes of the mineral particles in the rocks, the thermal conductivity and thermal diffusivity of the rock increase, while the relationship between the specific heat capacity and the particle size of the mineral is not obvious. Water content imposes highly impact on thermal properties. The thermal conductivity of rock under saturated conditions is 2%~17% higher than that under dry conditions, and the thermal diffusion coefficient is increased by 1%~16%, while the specific heat capacity is reduced, with a reduction range from 3. 08% to 21. 79%.