An Introduction to the Technical Aspects of Installing Submarine Cable Networks

The period most critical to the success of laying cables underwater is the beginning. If you install a fiber-optic deep water monitoring system with haste, the effort of acquiring the equipment will be for naught. The most critical period during the polarization process is the first 6 - 12 months. If the structure achieves full polarization during this period, and maintenance current density levels are as projected, then it is unlikely that any long term problems will develop.

Most deep water production facilities have a dedicated ROV to support ongoing drilling and production operations. By utilizing this facility when formulating a monitoring program, you will also be able to maximize the utility of the cables. You can also find a range of ROV interfaced systems available for pipeline and structural surveys. With optionally intelligent fixed monitoring systems deployed to store data, these systems  periodically transmit this data to the surface via an ROV umbilical cable.

Tips for Installing a Deep Water Monitoring System Successfully

You can find several portable measurement systems available for ROV interface. It is important when employing such systems, make sure that signals are not corrupted in the ROV umbilical cable (the device which transmits data to the surface). A high-percentage method for eliminating this problem is digitizing the data on the ROV before it goes into the umbilical cable. Via the digitizing method, you can handle data with a computer topside. Deep water research and production facilities use these widely in the offshore area.

When considering an ROV mounted system, make sure to procure a subsea ground facility. Usually in the form of a tip or spike contact, this subsea equipment  serves several functions. A subsea ground facility can compare a subsea ground with a topside ground, immediately correcting any signal corruption in the ROV umbilical. The subsea ground facility provides a reference ground on systems such as subsea completions where in cases where there is no topside structure. This deep water monitoring system can also verify electrical continuity or isolation of subsea structures such as riser clamps, retrofitted anodes, piles within pile guides, etc. Finally, one system uses the tip as one of two electrodes in an on-line resistivity measurement system.

Where To Monitor When Installing a Submarine Cable Network

You will have to choose specific locations to monitor a Submarine Cable Network depending on the design of the structure you are working with. However here are some typical guidelines regarding monitoring the installation of your deep water monitoring systems. When operational monitoring (as opposed to research testing) you must assess the critical areas on the particular structure.

Consider this criticality both in terms of risk and consequences. Whether in fear of under-protection and failure or the expensive cost of securing adequate protection, you may want to get hold of load bearing nodes.  Load bearing nodes are both structurally critical items as well as difficult areas to protect. You should also consider monitoring heavily congested areas such as conductor bundles, tubing runs and skirt pile areas.

Other critical locations are risers, pilings near the mud line, subsea well heads and mooring or tethering systems. Most offshore structures, regardless of their design, are symmetrical about two axes. Most designs of cathodic protection systems follow this symmetry, so you will normally select typical quadrants for monitoring, thus covering all critical areas with the minimum of instrumentation.

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Created on Aug 28th 2020 01:45. Viewed 269 times.

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