A Well Logging Method of Thermal Conductivity Using Line Heat Source

In recent years, many people have concerned with global warming and energy conservation technique. The geoheat extraction system in soil is expected one of the important techniques and begun to use in Japan. In order to design and estimate the effectiveness of the system, the data of thermal properties of earth formation are very important. In common, the capacity and efficiency of heat exchange system is evaluated by Thermal response test (TRT) using real borehole that was drilled for the heat extraction. If we can use small aperture borehole such as drilled for Standard penetration test (SPT) to estimate thermal property, the method will be instrumental. With the proposal method, we can explain the effectiveness of geoheat extraction system and advise the system as a possible option to building constructor or customer. So far, the Cone penetration test (CPT) technique using small penetration rod applied line heat source has been conducted by present authors. However, in the case of using small borehole, we have to evaluate the effects of the filling material of borehole, the position of sensor and casing material. To confirm the applicability of the method, we have conducted both computer simulation and field experiment. As a result, we are able to demonstrate the effectiveness of the proposed method.