An R&D project funded by the Japanese Ministry of the Environment on geothermal well drilling technology is under way. The purpose of the project is to develop an environment-friendly, low-cost drilling technology for highly deviated wells (2500m horizontal offset and 70 degree inclination) in order to access high-temperature geothermal resources from outside national parks, where they are often found. In the course of the project, a high-temperature, memory-type PTS (Pressure, Temperature, and Spinner) + fluid sampler tool has been under development.

In order to apply the tool to the highly deviated well, roller centralizers were attached. The specifications of the pressure and the temperature sensors are up to 34.5MPa and 350 deg. C, respectively. The capacity of the sample chamber is 500 mL and the sampler can acquire brine, vapor, and/or two-phase fluid. The tool was applied to geothermal production wells for the first time in Japan, and PTS data and downhole fluid samples were successfully collected simultaneously. Because the roller centralizer was effective in centering the tool in the hole, the tool up-and-down behavior was very smooth and the spinner data were of excellent quality.

In this paper, development of the high-temperature PTS + fluid sampler tool and its application are presented.

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