High Data Rate MWD Mud Pulse Telemetry – From Mysteries to Discovery

Abstract

Our new approach to MWD mud pulse telemetry offers significant increases over conventional data rates. Using waveguide acoustics, we show that common drilling communications channels support carrier frequencies exceeding several hundred Hertz. Such signals are prone to attenuation over large drillpipe distances. Low power, self-spinning “turbosirens” are designed, providing high torque and rotation rate performance at all flow rates without electric or hydraulic motor drives. The sirens rotate, drawing only on the kinetic energy of the mud, like flapping flags oscillating in wind. Our turbosirens are minimally affected by LCM jamming. Turbine and siren rotor components ride freely along longitudinal trenches built into rotating shafts. Both magically float into the oncoming mud as it slows down, thus, widening all gap spaces and freeing any trapped debris even as both travel opposite to the mud flow. In addition, “turbosirens in series” signal superposition, drawing on constructive wave interference, offers strong pressure signals at high frequencies without mechanical complexity. Rapid modulations are possible, also without motor drive, relying on rapidly acting electro-magneto rheological brakes powered by turbosirens. To take advantage of hardware capabilities, “Intelligent i FSK” telemetry, or Frequency Shift Keying creates clean signals without the ambiguous wave reflections found with PSK and randomized time shifts. Frequency pairs are not selected arbitrarily, but chosen from “neighboring pressure peaks and valleys” in frequency space as determined from bottomhole assembly waveguide Fourier analysis. Finally, surface signal processing and reflection removal are facilitated with time delay and differential equation algorithms. For deep wells where multiple drill pipe reflections are unlikely, analytical solutions for both are obtained assuming single reflections which do not involve windowing challenges and complicated digital filter design. Software and hardware developments patented, published and validated over the years, are integrated, refined and readied for controlled field tests.