Challenge of Temperature Control for Downhole Instruments in HTHP Reservoir

With the further exploration of oil and gas, we have to search for new resources which buried in deep strata, and most of the deep and ultra-deep wells are categorized in high-pressure/high-temperature (HPHT) wells. The problem of high temperature and the challenge to the existing downhole equipments are becoming increasingly prominent, where the drilling depth is severely restricted. The conventional measurement while drilling tools with common electronics will experience very high failure rates at these conditions. One of the solutions is called the active cooling technology, which can transfer the heat from electronics system to downhole environment. By this way, the temperature control of downhole instrument circuit system is realized. The active cooling technology is expounded in this paper, expecially about the principles and development status of each system. After evaluating and analyzing the characteristics of this technology, the function of heat transfer and constituent elements for the cooling system are summarized. The study from this work demonstrates the future work for downhole cooling technology: large refrigeration capacity, small size, strong adaptability and modularization.