Telemetry systems with compensation for signal degradation and related methods

摘要

This invention comprises systems, methods and apparatus for mud pulse telemetry involving sending benchmark pulses with known characteristics (such as amplitude or duration) from the surface to the BHA, measuring those characteristics at the BHA, using those measurements to predict the likely attenuation of downhole-to-surface mud pulse transmissions, and adjusting those transmissions to compensate for high attenuation or to obtain energy savings (or transmission rate increases) during low-attenuation conditions. Further refinements on these systems and methods, particularly concerning the use of signal-to-noise ratio measurements at the surface to more efficiently predict attenuation, are also disclosed.

主权项

1. A mud pulse telemetry system comprising:
a first pulse sensor in fluid communication with a first pulse generator by way of a drillstring; and a second pulse generator in fluid communication with a second pulse sensor by way of the drillstring; wherein: the first pulse generator is configured to transmit a benchmark pulse with a known characteristic to the first pulse sensor, the benchmark pulse propagating in a first direction along the drillstring; the first pulse sensor is configured to measure the known characteristic of the received benchmark pulse; a first processor is configured to generate one or more telemetry parameters based at least in part on the known characteristic of the received benchmark pulse; and the first processor is configured to control and/or cause a second processor to control the second pulse generator to transmit to the second pulse sensor a set of one or more mud pulses according to the one or more telemetry parameters, the set of one or more mud pulsed propagating along the drillstring in a second direction opposite to the first direction wherein the first processor is configured to determine an attenuation prediction factor according to:attenuation⁢⁢prediction⁢⁢factor=CS-CDCS where: CS is the value of the known characteristic of the benchmark pulse at the time the benchmark pulse was transmitted by the first pulse generator and CD is the value of the known characteristic of the benchmark pulse as measured by the first pulse sensor.