Improving the Performance of Geothermal Pressure, Temperature, and Spinner Tools used in Down-Hole Measurements

Abstract

Pressure, Temperature and Spinner (PTS) probes/tools are commonly used in the characterization of geothermal wells during drilling, completion testing, and monitoring throughout the life of the well. These well tests include static formation temperature testing, water loss surveys, injection fall-off tests, warm-up surveys, flowing surveys, and other tests. The main challenge when using these tools is to ensure that the electronic components of the different sensors, signal processing, and memory are not affected by the heat generated from the tool’s energy supply (battery) and from the high temperatures in the well. This buildup of heat limits the working time available for the tool down the geothermal well and can affect/limit the quality and use of the data. A survey was conducted on the current state of electronics and electronic packaging for the use in geothermal, oil and gas probes/tools. Techniques for high temperature performance were reviewed including the use of Dewar flasks for the thermal insulation of electronic components of the PTS tool and the use of electronics for operation at higher temperatures. An in-depth analysis of the performance of the widely used commercial PTS tool developed by MBCentury Ltd. was completed using SolidWorks™ thermal simulation software. The model was optimized and compared to the PTS probe test data taken from five different test cases. The calibrated model was used to test several different heat sink materials. The results showed that the current tool design cannot be easily optimized further. However, predictions based on the model showed an alternative operating procedure that can provide an increase in the operating down-hole time of the tool.