One of the main challenges in designing oil & gas downhole wireline logging tools for high temperature and high pressure (HTHP) environments is to put together the most efficient thermal packaging to enhance the tool’s temperature survival time. In general, not all electronic components and sensors can withstand severe downhole temperature (max 500 degrees Fahrenheit). For those heat sensitive components, their electrical response and performance either decay or in some cases they completely fail when their temperature exceeds 300° F. In oil & gas wireline logging applications, the heat sensitive components can be thermally protected inside a Dewar vacuum flask that includes one or two thermal isolators and heat sinks. Cooler electronic components results in longer logging times that lead to a much higher performance and profitability. This paper first discusses the development of a one-dimensional analytical model to determine the transient temperature of heat sensitive sensors and electronic components in wireline logging tools. Second, it introduces a new and improved thermal packaging scheme based on a newly developed and commercially available nanoporous material. This material has a very low thermal conductivity and is used as a thermal shield between the outside environment and the electronics inside the flask. The new packaging scheme also includes a new design for the heat sink which is made of several solid disks separated by this nanoporous material. Results from this new design have shown roughly a 30% improvement compared with the conventional design. Results from both analytical and laboratory tests are discussed in this paper.

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