Measurement While Drilling, 2nd Edition

Chapter 16MWD Turbosiren – Principles, Design and Development

In conventional Measurement While Drilling technology, several preferred approaches are available, namely, “mud pulse telemetry,” acoustic “banging the drillpipe” telemetry, wired pipe and electromagnetic. Recently, various “unified telemetry” implementations have been developed, which combine mud pulse and electromagnetic methods within a single tool, providing increased service reliability and redundancy, plus operational coverage for foam muds that attenuate sound waves rapidly. These attest to the robustness and continuing popularity of mud pulse technology which, unfortunately, is described in the popular press in three over-simplifying flavors: “positive pulse,” “negative pulse” and “continuous wave,” referring to mud siren embodiments.

16.1 Background and Motivation.

There are no good reasons why the former two approaches cannot be operated in continuous mode if mechanical oscillations are rendered sufficiently rapid. For example, the excuses commonly offered for (high signal strength) positive pulse tools, because their pistons work literally against high velocity and high density drilling muds, are excessive force and power requirements. Mud sirens improve data rate because they do not completely stop the oncoming flow – because they move perpendicularly, as opposed to inline with the flow, higher data rates are possible. Unfortunately, the same through-flow that allows faster oscillations are also responsible ...