Thermal management systems for electronics using in deep downhole environment: A review

During the exploration of underground energy such as oil and gas and the application of geothermal energy, more deep drilling wells are developed. To meet the increasingly multifunctional demand of downhole equipment, many high-temperature sensitive electronics should be integrated and operate under deep downhole environment at the temperature over 200 °C. In this regard, the application of cost-effective thermal management strategies for the electronics is critical to ensuring the stable and reliable operation of downhole tools. This paper presents a review on applicable thermal management systems (TMSs) of electronics operating under deep downhole environment. Firstly, the structural characteristics, thermal performance and applicable restrictions of active and passive thermal management strategies used for downhole devices are detailly discussed. The merits and demerits of various TMS are also summarized. Meanwhile, due to the high heat flux transferred from the external environment, reviews on the thermal insulation shielding are also emphasized. As a result, the thermal management methods are divided into two categories based on the heat sources and heat dissipation terminals. Meanwhile, future developments of various thermal management approaches are discussed, aiming to serve as a reference guide for engineers and promote the progress of the next-generation equipment TMS in downhole environment.