In 2012 FHP were approached to develop and hire out a modified LCE (Linear Cable Engine) system to lay LoFS (Life of Field Survey) cable off the east coast of Brazil in the BC-10 Field. Along with the aim of improving current LoFS lay methods, this project had the added challenge of being the deepest LoFS system ever installed at 1,800m depth.
|Aim||Improving current LoFS lay methods|
FHP had previous experience laying LoFS cable in the North Sea in 2010, and while successful FHP identified several areas for improvement. The seismic pods on the LoFS cable are sensitive to pressure and linear tension therefore in the past when using a standard LCE the wheel pairs have been manually opened around pod by the operator. This lay procedure presents the following short comings:
- Inefficiencies – This system is slow and laborious as the lay has to go at a speed the operator can safely open and close wheel pairs around the pods.
- Human Error – When relying on the operator to open and close the wheel pairs around the pods human error is always a possibility which can result in wheel pairs being opened or closed out of sequence, the pods going through the closed wheel pairs, or worse the cable grip being lost. Any of these situations could result in damage to the product or a dangerous situation for the crew.
- Depth Limitations – Greater depth lays require machines with greater tensions, due to the fact wheels are being opened around the pods more wheel pairs are required to give the same tensions, this in turn means that larger machines are required.
FHP attempted to test the LoFS cable to destruction using two 6 pair LCEs at our facility. The pinch pressure, tyre pressure, and line tension were varied in order to find the best LCE set up and to devise a modification plan which allowed for smooth continuous lay of the cable without damage.
Development & Further Testing
From the initial testing a system was designed to allow constant cable passage through the LCE with minimal operator input. FHP’s standard LCE was modified with proximity controls, counters and a PLC with a bespoke program. After further testing with our customer this new system was approved and lined up for the BC-10 project.
BC-10 LoFS Cable Lay
In early 2014 the modified LCE was used to lay the LoFS cable for the BC-10 field at a depth of 1,800m. The LCE was operated by 4 of FHP’s engineers with complete success.