Downhole electromagnetic and mud pulse telemetry apparatus

摘要

A measurement-while-drilling (MWD) telemetry system comprises a downhole MWD telemetry tool comprising a mud pulse (MP) telemetry unit and an electromagnetic (EM) telemetry unit. The MWD telemetry tool can be configured to transmit data in an EM-only telemetry mode using only the EM telemetry unit, in an MP-only mode using only the MP telemetry unit, or in a concurrent telemetry mode using both the EM and MP telemetry units concurrently. When transmitting data in the concurrent telemetry mode, the telemetry tool can be configured to transmit in a concurrent confirmation mode wherein the same telemetry data is transmitted by each of the EM and MP telemetry units, or in a concurrent shared mode wherein some of the telemetry data is transmitted by the EM telemetry unit, and the rest of the telemetry data is transmitted by the MP telemetry unit. The telemetry tool can be programmed to change its operating telemetry mode in response to a downlink command sent by an operator at surface.

主权项

1. A method of transmitting downhole measurement data to surface comprising:
(a) reading downhole measurement data; (b) selecting an available telemetry transmission mode from a group consisting of: mud pulse (MP)-only telemetry mode, electromagnetic (EM)-only telemetry mode, MP and EM concurrent shared telemetry mode, and MP and EM concurrent confirmation telemetry mode; (c) when the MP-only telemetry mode is selected, encoding the measurement data into a first MP telemetry signal and transmitting the first MP telemetry signal to surface, (d) when the EM-only mode is selected, encoding the measurement data into a first EM telemetry signal and transmitting the first EM telemetry signal to surface; (e) when the concurrent shared telemetry mode is selected, encoding a first selection of the measurement data into a second MP telemetry signal and a second selection of the measurement data into a second EM telemetry signal, and transmitting the second MP and EM telemetry signals to surface; and (f) when the concurrent confirmation telemetry mode is selected, encoding the same measurement data into a third MP telemetry signal and into a third EM telemetry signal; and transmitting the third MP and EM telemetry signals to surface ; and wherein the measurement data comprises gamma, shock, vibration and toolface data and when the concurrent shared telemetry mode is selected, the method further comprises encoding the gamma, shock and vibration data into the second EM telemetry signal and encoding the toolface data into the second MP telemetry signal; or, encoding the gamma and toolface data on the second EM telemetry signal and encoding the shock and vibration data on the second MP teletry signal; or, encoding the gamma data on the second EM telemetry signal, and encoding the shock, vibration and toolface data on the second MP telemetry signal.