INSPECTION/MAINTENANCE Vibration monitor reveals well collision potential on Gullfaks

An on-line vibration monitoring system combining virtual real-time performance with substantial cost savings has been launched by Icon Nordic. Known as Iconet, the system is already in operation on Statoil's Gullfaks C platform.

Icon Nordic has made full use of state-of-the-art electronics and computer technology to provide a practical system suitable for both retrofit and new installations, according to director John Slight. In terms of basic architecture, Iconet is a distributed networked system, in which each node contains a microcomputer and network controller that carries out data acquisition tasks as dictated by the host computer.

In contrast to the heavy cabinets required by rival systems, the node boxes to which the signals from the sensors are directly relayed are both small and relatively light. These are advantages in themselves in an offshore context, but bring the added benefit that each box can be placed as close to the machinery to be monitored as possible. This greatly reduces the length of co-axial cable needed to link the main sensor to the box, which is one of the major cost elements in such systems. Once it arrives at the box, the signal is changed from analogue to digital, allowing the use of much cheaper four-core telephone cable for onward transmission.

The cost of rival vibration monitoring systems is around $500 a vibration point, excluding software, while Iconet works out at around $300 a point, including software, Slight says. When the company tendered its system to a UK refinery, its bid was 90% less than its nearest rival on cabling, he says.

Flexible maintenance potential

The data is collected and processed in a PC which is operated by means of a user-friendly Windows system. Icon Nordic provides software for analysing the data, including a diagnostics program to pinpoint areas of sub-optimal functioning. Armed with effectively real-time monitoring, the user is kept constantly updated on the state of the machinery and given early warning of trends to wear or defect. Thus he can implement a flexible maintenance programme, avoiding the unnecessary expenses entailed in preventative maintenance systems, according to Slight.

Gullfaks

Iconet is now installed on the Gullfaks C platform following an order from the drilling contractor Transocean. This is a two-point system installed at the wellhead to monitor vibration in the drill-string. The primary function in this case is to detect whether a currently drilling well collides with an existing well - the large number of wells drilled from the platform has created congestion in the area immediately beneath it.

A 500-point system has also been supplied to a leading offshore pump manufacturer for installation on its test-bed. Here, in addition to vibration, it will be used to monitor a wide range of functions, including static pressure and flow, valve position control, and RTD inputs.

A 300-point system is also being supplied to Cable & Wireless for the vibration monitoring of the engines and much of the machinery on its newbuild cable-layer Cable Innovator. The vessel uses diesel-electric engines, as do most supply boats, tugs and other vessels active in the offshore sector.

With Iconet well on the way to achieving market accceptance, Icon Nordic is now at an advanced stage in its next project, the development of a portable pressure recording system to monitor the condition of the cylinders on BOP stacks.

For more information contact John Slight, Icon Nordic: telephone +46 431 544 00 or fax +46 431 544 01.