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TRANSMISSION CABLE FOR MONITORING SUBSEA PIPE

IP.com Disclosure Number: IPCOM000245520D
Publication Date: 2016-Mar-14
Document File: 3 page(s) / 67K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention is a means of transmitting monitoring signals over long distances along subsea pipe such as flexible risers or flowlines without unduly attenuating the signal strength. An insulated electrical waveguide cable is used, that is incorporated into the flexible pipe structure, for monitoring damage to the flexible pipe and consequent seawater ingress. The cable may use coaxial configuration for low signal attenuation over long transmission distances. Wherever the flexible pipe meets the flowline, continuity of signal is ensured by connecting the signal cables through custom-made connectors. The insulated connectors are provided along with the end-fittings of the flexible pipe and are configured to mate with corresponding connectors on the subsea flowline. The invention increases the distance over which the seawater ingress monitoring systems can operate so that they can be used to sense annulus flooding in flexible pipes that are located in deep water or are not connected to the topside, e.g. flowlines.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

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TRANSMISSION CABLE FOR MONITORING SUBSEA PIPE

BACKGROUND

    The invention relates to system for condition monitoring of marine pipelines and in particular to system for condition monitoring of flexible pipe used to transport production fluids, such as oil and/or gas and/or water. Flexible pipelines are particularly useful in connecting a sub- sea location to sea level location such as floating production, storage and offloading platform. The pipe body is typically formed as a combination of layered materials that form a pressure-containing conduit and may include metallic armor layers and polymer sealing layers. While the pipe can be designed for particular loading conditions, there remains a risk of defects arising within a flexible pipe. A defect may comprise damage to an outer wall of a flexible pipe body resulting in the ingress of seawater into an annulus within the pipe body such that seawater fills voids between the armor layer wires and other structural elements of the pipe. One type of monitoring system is used to detect such seawater ingress into the annulus of flexible pipe.

    An important feature that is required in the transmission cable to work with the monitoring system is that it must be in contact with the environment around it so as to ensure that water can contact the conductor and so trigger the seawater ingress alarm system. The transmission cable, on the other hand, must be electrically isolated. The overall purpose of the invention is to provide a system of isolation to increase the distance over which the seawater ingress monitoring systems can operate so that they can be used to sense annulus flooding in flexible pipes that are located in deep water (> 1000 m depth) or are not connected to the topside, e.g. flowlines.

BRIEF DESCRIPTION OF DRAWINGS

The invention discloses a system for monitoring oil/gas flowlines subsea, wherein:

FIG. 1 shows a system of insulated signal cable and end fittings for extending the range over which flexible pipelines can be monitored.

DETAILED DESCRIPTION

    The invention is a means of transmitting monitoring signals over long distances along subsea pipe such as flexible risers or flowlines without unduly attenuating the signal strength, as shown in FIG. 1. As shown in the figure, insulated electrical waveguide cable is used, that is incorporated into the flexible pipe structure, for monitoring damage to the flexible pipe and consequent seawater ingress. The cable is such that low signal attenuation over long transmission


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distances can be ensured, such as by using a coaxial configuration. Wherever the flexible pipe m...