Geothermal response test

Keywords Geothermal response test, ground thermal conductivity, line source, GENOPT, TRNSYS, borehole heat exchanger... 

During the many tests we performed we found that that ground water flow will significantly affect results of the In Situ Geothermal Response Test. This is especially clear in the CUSUM graphs, that show an increasing estimate of ground thermal conductivity with time. The reason for this is that the effect... 

Figure 55. Geothermal response test with combined heat extraction/heat injection and different energy levels, shown are the borehole heat exchanger flow and return temperatures and the calculated heat flux. Borehole flow rate is not shown in the graph...

The Geothermal Response Test as developed by us and others has proven important to obtain accurate information on ground thermal properties for Borehole Heat Exchanger design. In addition to the classical line source approach used for the analysis of the response data, parameter estimation techniques employing a numerical model to calculate the temperature response of the borehole have been developed. The main use of these models has been to obtain estimates in the case of non-constant heat flux. Also, the parameter estimation approach allows the inclusion of additional parameters such as heat capacity or shank spacing, to be estimated as well. 

Tenma, N., Yamaguchi, T., Tezuka, K. Karasawa, H. 2000. A study of the pressure-flow response of the Hijiori reservoir at the Hijiori HDR test site. In Proceedings World Geothermal Congress 2000, Kyushu-Tohoku, Japan, 28 May-10 June 2000, 3917-3920. 

There were three successful Modular Formation Dynamics Tester (MDT) tests that provided two important pieces of information (1) evidence of hydrates through the reservoir response to pressure simulation and (2) geomechanical/geothermal measurements at pressure production interval. 

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