The Grane platformoperated by StatoilHydrois located in the Norwegian Sea off the coast of Bergen in Norway. It has successfully installed Emerson Process Management’s wireless self-organising mesh field network to monitor wellhead annual pressure and heat exchanger pressures – despite the crowded metal wellhead environment there (Fig.1). Emerson says that its self-organising wireless mesh technology is ideally suited to the application of wireless technologyenabling remote monitoring and control of the process in difficult to reach areas. The company believes that the network on the Grane platform is the first offshore wireless installation in Europe. "We had some concerns that this new technology would work reliably in the harsh environment of our offshore platform" said Geir Leon Vadheiminstrument leadGrane operationsStatoilHydro. "We also needed to address the issue of how we would integrate the data gathered by the wireless gateway into a third party system. As it turns outthe integration was easy and the performance of the Smart Wireless transmitters has exceeded our expectations." Challenging environment The wellhead area is crowded with metal pipe workmetal walkways above and belowtogether with other metal obstructions. Despite the challenging environmentas each transmitter was powered upthe devices found the gatewayand the mesh was established. As new devices were addedthey quickly and easily joined the mesh. Signal strength and consistency during the operational period has been described as excellent. The wireless network enables continuous monitoring of pressures and eliminates the need for daily visits to the wellhead to manually record gauge readings. Continuous monitoring enables unusual readings to be identified earlier and action taken to investigate and rectify faults before they develop into serious problems. The Smart Wireless network on the platform includes 22 wireless Rosemount pressure transmitters which replace traditional gauges (Fig.2). Ten pressure transmitters are mounted on a wellhead and used to measure annular pressure. A further 12 pressure transmitters monitor inlet pressure and pressure drop over the heat exchanger. Each transmitter relays data back to the operator consoles in the control room. Installation was quick and easy with a gauge adapter fitting used to allow a direct ‘screw in’ replacement. A wireless gateway was mounted outside the process area on one side of the platformat a height where it oversees the wellhead area. "We are delighted with the performance of the Emerson Smart Wireless network in these challenging conditions" added Vadheim. "Following a short training programmeour instrument engineers are very confident about adding more wireless devices to our installation as required. These typically take around two hours to install compared with up to two days for a conventional wired unit." Following the success of this installationStatoilHydro is planning to install Emerson Smart Wireless transmitters on other offshore platforms that it operates in the area. Making the most of mesh At the heart of Emerson’s Smart Wireless approach is the self-organising (mesh) network. The company says it is secureinfinitely configurablewith data reliability of greater than 99percent: using one ensures an adaptiveflexible approach to wireless that defies the 'canyons of metal' which define most plants. Unlike many approaches to in-plant wireless that require direct line-of-sight between the instrument and the communications gatewaythis approach ensures the greatest network integrity by allowing devices to communicate with each other. This means there is no single point of failureevery device serving as a network connector. As a resultsays the companySmart Wireless in real world customer trials delivers greater than 99percent data reliabilityconsistently. This is primarily enabled by the self-organising nature of the technology platform. In the event a temporary obstruction blocks a direct connectionthe network automatically reroutes the signal to an adjacent deviceensuring network reliability and data integrity. One of the greatest barriers to adopting new technologies or adding new points of measurement is the sheer cost. For every dollar you spend in instrumentationyou spend US$8-9 in labourmaterialsengineering and more. One of Emerson’s main selling points is that its approach can save more than 90percent over traditional installations – effectively giving ten points of measurement for the price of one wired. Then there is the line-of-sight argument. In traditional point-to-point or line-of-sight wireless approachesreal-world network and data reliability can be as low as 40percent because of dynamic and harsh process environments. Process manufacturers need greater integrity in their network. By contrastEmerson points to its 99percent reliability. This is primarily enabled by the self-organising nature of the technology platform. A final benefitsays the companyis use of the proven time synchronised mesh protocol (TSMP) that can be supported by both 900MHz and 2.4GHz (IEEE802.15.4)an approach that offers an unparalleled robustness. It is tolerant to almost all interferenceswhether permanent or temporaryand reliably coexists with other wireless networks.
