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Synchronization of data acquisition and telemetry processes

IP.com Disclosure Number: IPCOM000188459D
Publication Date: 2009-Oct-08
Document File: 1 page(s) / 12K

Publishing Venue

The IP.com Prior Art Database

Abstract

Due to their nature, all data from MWD/LWD tools are referenced to time. Using time-depth profile one can convert time of acquisition into depth where the measurement was done. To have this information in real-time MWD/LWD data are transmitted to the surface using some kind of the telemetry (mud pulse, EM, wired pipe). In many cases it is not possible to send both measured value and time to the surface when it was taken due to the limited bandwidth of the telemetry. In this case, time when measurement was done is estimated from surface time when it was received by subtracting all the propagation and processing delays in the system. It is necessary to have accurate information about the delays for accurate conversion to depth. While generally all the processing delays and propagation delays are known or can be estimated sufficiently accurately there is step in data handling which has an uncertain time delay. It is due to the fact that data acquisition and telemetry processes are not synchronized. Data acquisition nodes collect data and produce new measurement at some time. Telemetry node sends measurements in some sequence and uses last available measurement from acquisition node when it is time to send it. Since this processes are not synchronized it is possible that measurement is was created some time before telemetry node gets it. Since this time delay is not deterministic it is not possible to take it into account when determining time of measurement from time when it is received on the surface. To avoid this problem it is proposed to synchronize telemetry process with data acquisition processes in such a way that measurements are produced by acquisition nodes right in time to be sent to the surface by the telemetry node. One possible way of doing it is to notify acquisition nodes in advance when telemetry node will need a measurement. This way acquisition node can take into account its acquisition and processing delays and initiate data acquisition at the right time.

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Title of Invention:

Synchronization of data acquisition and telemetry processes

Abstract of the Invention:

Due to their nature, all data from MWD/LWD tools are referenced to time. Using time-depth profile one can convert time of acquisition into depth where the measurement was done. To have this information in real-time MWD/LWD data are transmitted to the surface using some kind of the telemetry (mud pulse, EM, wired pipe). In many cases it is not possible to send both measured value and time to the surface when it was taken due to the limited bandwidth of the telemetry. In this case, time when measurement was done is estimated from surface time when it was received by subtracting all the propagation and processing delays in the system. It is necessary to have accurate information about the delays for accurate conversion to depth. While generally all the processing delays and propagation delays are known or can be estimated sufficiently accurately there is step in data handling which has an uncertain time delay. It is due to the fact that data acquisition and telemetry processes are not synchronized. Data acquisition nodes collect data and produce new measurement at some time. Telemetry node sends measurements in some sequence and uses last available measurement from acquisition node when it is time to send it. Since this processes are not synchronized it is possible that measurement is was created some time before telemet...