Communication system for down-hole measurement tools based on real-time SNR characterization in coaxial cable used as communication channel

Down-hole oil and gas industries are important users of high temperature electronics. In these applications the operating temperature is function of the underground depth of the wells. Oil reservoirs in Mexico are located at mean depths of 6,000 m and the typical geothermal gradient is 25°C/km, however in some areas it is greater. Consequently, the requirements for measuring thermodynamic and geophysical parameters, for instance pressure, temperature, vibration and multiphase flow, are a challenging task. Accomplishing these necessities requires a complete signal communications chain of high-performance components and effective communication techniques to provide system reliability. Nevertheless, noise interference, cable attenuation and thermal drift of the front-end passive electronic elements can lead to poor signal-to-noise ratio (SNR) and possibly loss of the communication link. This paper describes a bidirectional communication system that exchanges data from a down-hole high pressure and high tempe...