Pumping the blackgold

Umuroa, the floating platform storage and offload (FPSO) facility for the Tui oilfield off the Taranaki coast, is up and running courtesy of, amongst others, New Plymouth-based industrial electrical contractor JLE Electrical Ltd (part of the nationwide JLE Group of companies). JLE, in partnership with New Plymouth contracting engineer Robt Stone & Co Ltd, assisted ProSafe Production, a Singapore-based Norwegian operating company, with the offshore hook-up and commissioning of the facility – a converted Suezmax oil tanker. JLE performed significant electrical instrumentation and automation duties in completing carryover work, as well as the pre-commissioning of field instrumentation and shutdown systems controlling the process, utility and gas treatment systems. Umuroa, translated from Maori, means “long on energy”. However, says JLE Electrical’s Taranaki manager Mark Thompson, the three-month project was long on other things too. “It was a task of mammoth proportions, and we worked long hours, but it was also a lot of fun. “It’s been a real challenge to manage the logistics of an offshore project such as this. There have certainly been a lot of variables on the project given the nature of the work, including rigorous safety requirements, and we had to be flexible enough to change plans if, for example, a good gust of wind hit the vessel,” he says. The 22 staff members, working two shifts, were ferried to work by helicopter on a fortnightly roster. Prior to commencing work, they had to undergo a one-day helicopter underwater evacuation training course to comply with international aviation safety rules. This, according to automation engineer Ravi Kadiyala, made for some “Fear Factor” moments! “We spent the morning learning procedures such as inflating life-rafts and life-jackets and using personal locating beacons. “In the afternoon we had to show what we’d learnt – they put us in a helicopter capsule above a swimming pool, dumped us into the water and told us to escape, first through one window and then the other. Then we were dumped upside down – nerve-wracking stuff, but good preparation for a possible emergency,” he says. Kadiyala says that when the JLE team arrived on the Umuroa, about five percent of the automation, electric, and instrumentation work on the infrastructure remained to be done in-situ. He explains the three-month automation project: “We had to do support and commissioning work for the three Allen-Bradley SLC5/04 PLCs (programmable logic controllers) and the Allen Bradley Panel View Plus 1000 HMI (human machine interface) unit for the gas compressor systems on board the vessel. “Our first job was to get the two Gas Lift Compressors (GLC), one for active duty and one backup, and the Vapour Recovery Unit (VRU) attached to them up and running. It’s a fairly unique set-up – not a lot of offshore projects use VRUs, and it was very interesting to work on.” However, Kadiyala says using the GLCs and VRU is a very cost-efficient and effective option to run the four Tui oil wells, which have a concurrent life expectancy of around a decade. The oil sucked up from the well in the seabed contains a variable percentage of natural gas. Before the oil is pumped into Umuroa’s storage tanks, a separator separates the natural gas from the oil. The gas lift compressor on duty then compresses the gas and scrubs the residual fluids from it. The fluids are reduced to water by another process, purified, and then disposed off. The VRU, in its turn, scrubs all remaining fluid traces from the gas with added compression. The compressed gas is used to heat water to run steam turbines to produce electricity for the Umuroa, with some pumped back into the well. The purpose of pumping gas into the well is to keep pressure inside the well at a certain level to ensure the desired outflow of oil, a very important consideration especially towards the end of the well’s life. The burned off-gas produces the spectacular 120-metre plus high flare header so characteristic of oil rigs. Kadiyala and the team had to check the programming on the PLCs and modify code as and where necessary to commission the compressor package, using RS Logix software. Each PLC controls its designated GLC package by monitoring inputs controlling outputs. Safety first Kadiyala says the whole process is designed in a very safe manner. The field pressure sensors ensure the pressure of the highly volatile gas mixture coming from the well stays within the set parameters determined by the ProSafe engineers. The level sensors ensure a set level of water. These parameters take into account many variables, including safety, so if certain variables are outside the set parameters, the entire oil pumping system shuts down. “That’s why it’s important that the monitoring system works perfectly, so the duty operator can do the required adjustments and the system can operate uninterrupted,” says Kadiyala. The team’s second job was to programme the Allen Bradley Panel View Plus 1000 HMI unit using RS View Studio software and get it ready for commissioning. The screen enables the duty operator to monitor, change, stop and start any process. “It was really long hours, but very interesting…I even got to do some good old-fashioned work with a screwdriver and pliers,” Kadiyala jokes. He says ship life is good – the “brilliant menu” would satisfy any connoisseur’s palate and he enjoyed the fresh sea air. “Of which I got a lot – the compressor packages are each around 12 metres long, and the VRU about three-quarters the size – not something you install inside!” The GLCs and the VRU were built by Technics Offshore Engineering in Singapore and are equipped with Ariel compressors. Ariel is a United States-based company. The instrumentation work on Umuroa continues, and apart from this and the automation project, JLE also provided support to the Umuroa’s Subsea7 Rockwater dive support vessel at Port Taranaki. The vessel laid down the undersea pipeline connecting the centrally anchored Umuroa to the four wells, an average distance of around 20 kilometres per pipeline. A Siemens S7-400 system utilising Profibus communications controls the vessel’s on-board crane, and JLE engineer Bronwyn Theobald and her team provided urgent spare parts for this equipment as well as engineering support to help resolve problematic Profibus issues. Team effort “We’ve enjoyed working for Robt Stone on this major project and ProSafe reports they’re extremely happy with the work we’ve done. This has certainly been a real team effort and a great experience for everyone concerned,” says Thompson. The Umuroa is JLE’s second offshore support project. Eighteen months ago the company carried out extensive work on the electrical and instrumentation component of Shell Todd Oil Services’ new on-shore gas production station, Pohokura, located in North Taranaki. However, says Thompson, the company, which was established in 1999 and now employs 140 staff, can support customers with a wide range of solutions, from electrical services, compliance and inspections and maintenance shutdowns, right through to automation. “All these services make the JLE Group a one-stop shop,” he says. Jenny Baker is an Auckland-based freelance writer.

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