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Low data rates, typically 1-3 bits/sec or less, are the norm in “mud pulse” Measurement-While-Drilling (MWD) systems. For example, “sirens” offering high carrier frequencies produce low-amplitude signals subject to severe attenuation; and strong signals from “positive pulsers” are slow since large forces are required to overcome mud inertia. Moreover, reflections, high pump noise, erosion and rapid power consumption affect all pulsers. This paper describes an integrated systems approach to high-data-rate telemetry. Source strength is enhanced using downhole constructive interference, and surface signal processing eliminates downward reflections and pump noise through “directional filters,” both drawing on wave-based methods. Hydraulic properties associated with torque, erosion, aerodynamic stability and turbine performance, and subtleties found in large-scale acoustic wave interactions, are studied using dynamic similarity. In particular, short and long wind tunnels are introduced with significantly reduced test times, cost and required labor. Experimental facilities, prototypes and signal processing methods are presented in detail.

Strategies in High-Data-Rate MWD Mud Pulse Telemetry