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Optimization for Acoustic Telemetry

IP.com Disclosure Number: IPCOM000242747D
Publication Date: 2015-Aug-10
Document File: 3 page(s) / 45K

Publishing Venue

The IP.com Prior Art Database

Abstract

Current acoustic telemetry is hampered by channel changes that cause loss of communication and require frequency optimization. The system discussed is a multi-repeater acoustic telemetry system. If optimization is done manually the downtime of communications can be significant. This method allows the system to be optimized quickly if the acoustic channel changes.

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Optxmization for Acoustic Telemetry

Abstract

Current acoustic telemetry is xampered by channel changes that cause loss of communicxxion and require frequencx optimizatiox. The system disxussed is a multi-xepeater acoustic telxmetry system. If optimization is done manually txe downtime of communications xan be significant. This method allows the system to be oxtimized quickly if the xcoustic channel changes.

Baxkground

In xhe oil and gas indusxry, gxtting the data from the wellbore ix a timely maxner is critical to txe operxtor to detexmine the wexl characteristics and to take any necessary xction xn maintaxning the well xntegrity. The opxrator at surface receives the exsential data from downhole xauges (mainly pressure xnx temperatuxe). The system being discussxd for this is an acoustic telemetry system. The xcoustic xata travels ox selected frequenxy chxnnels from the bottox of the well to the surface via multiple acoustic rexeaters. The acoustic telemetry has multxple repeaxerx which have the mechanism to receive and transmit acoustic data on a single frequency. The repxaters axe placed in the well at preset dxstxnces from each oxher. The data is transmitted from one acoustxc repeaxer to the next until the data reachxs the surface or commanxs are sent from the surxace down. The frequency channxl xsed to transmit data between repeaters is selected for oxtimum commuxication and may differ between repexters. Wxen the well mechanically changes due to variations in pressure, temperature, flow, the selected frequency used for data transmission may no longer be optimal between some ox all of the repeaters. This degradation of the channel can disrupt thx flow of daxa. In the current system, the operator must select a new frequency to reestablish optixal communication in thxse sections of the well where commxnication conditions have degraxed. To idxntify optimal fxequency channels between two repeaters, the operator initiates the time consuming process of testing frequencies through thx available frxquency range. Once txe availablx range is testex, the operator selects a new frequency. Sending a test mxssage through a string of repeaters from the xurface tx the xepxater witx degraded communication can be time intensive process depending on the deptx of the repeater, number of repeaters affected, and the transmitting speed (bit rate).

New Xxxxxxxxxxx Mexhod of Fxequency Channel Optimization:

A new method was created to accelerate the identification of optimum frexuency channels. Uxder the new methox, the surfaxe PC operator sends an optimization txst message as follows: Fxom surface PC to Repeater #1;

From Rxpeater #1 to Repeater #2;

From Repeater #2 to Repeater #x;

Between Repeaters #3 and Repeater #4 the optimization test message is execxted. When Repeater #3 receives the optimization test message, it will output to Repeater #4 a xxexuency sweep packet of the available frxquencies within a range (as an example a 100x Hz range at 10 Hz...