Publications Details
Tool development and application: pressure, temperature, spectral gamma ray logging of the SB-15 well
Sandia`s involvement with downhole instrumentation dates from the mid 1970s when work was centered on the development of a high-temperature acoustic borehole televiewer, and the establishment of a list of high- temperature component parts such as resistors, integrated circuits, and sensors. This work evolved into the development of memory logging devices for the US Continental Scientific Drilling Program. These tools were of low cost and very easy to use. Their deployment resulted in scientific advancement in understanding geothermal formations, and a thrust of the current program is to move memory tools from the scientific realm to the commercial environment. The tools developed and utilized in the SB-15 well among other field tests are completely self- contained in that power is obtained from batteries and data are stored in an electronic memory system. Three memory tools form the backbone of the initial Sandia tool suite. Pressure/temperature measurements are necessary for the evaluation of geothermal reservoirs, and they are relatively simple to make. Thus, the initial Sandia program concentrated on such a tool, and it has been successfully used in SB-15. This tool will form the basis for future tools since many engineering principles were proven in its evolution. This pressure/temperature tool combination is very useful in characterizing the geothermal reservoir. Another tool in the Sandia suite measures the natural gamma rays from the formation. This spectral gamma ray tool is useful in defining lithology, paleoflows, and certain clays. SB-15 well logging history and a preliminary interpretation of the data is presented in this report.