As it underscored the global tiers of safety mechanisms taken in the pipeline installation and delivery of gas for this country’s Gas to Energy (GTE) project, ExxonMobil says that the laying will be completed by the end of this year and the pipes will be filled with nitrogen until government’s completion of the integrated plant.
“We will not start-up bringing gas onshore until the plant is ready. The plant has a safety system that allows you to start up properly. We have to wait until the plant is ready. In the meantime, we will do what is called inerting the pipe, which is preserving the pipeline. You preserve a pipe by putting a gas that is inert that doesn’t combine with anything, doesn’t corrode with anything, etcetera,” GTE Project Manager Friedrich Krispin told Stabroek News during an interview last week.
“So nitrogen will be inside the pipe. We fill it up with nitrogen and then we wait and whenever the plant is ready, we will release all of the nitrogen, which doesn’t cost anything to the atmosphere, then we start bringing in gas,” he added.
The GTE project is divided into three components – Pipeline, Power/ NGL (Natural Gas Liquids) Plant, and Transmission Line/Substations. The Pipeline component includes a 250-kilometre 12-inch pipeline from two Floating Production, Storage and Offloading platforms (FPSOs) to deliver some 50 MCF/D (1 MCF = 1,000 cubic feet/D= per day) of gas to shore, although the pipeline has the capacity for 120-plus MCF/D.
The Power/NGL Plant component is the 300 MW Combined Cycle and NGL Facility while Component 3 will have Transmission Line/Substations of 85 km of 230 & 69 KV Transmis-sion Lines, three new substations, and upgrades to two other sub-stations.
The pipeline aspect for which ExxonMobil is responsible in the three-pronged project could be completed as early as October of this year but the company’s project schedule has it being done by the end of this year.
The GTE Project Manager gave a technical breakdown of what it entails to lay the 12-inch pipeline from offshore in the Stabroek Block to onshore at Wales in Region Three, the location of the project site.
With carbon steel pipelines procured from neighbouring Brazil, ExxonMobil’s lead project engineer explained that they must ensure the specifications are rigidly adhered to because the project cannot afford any errors.
The pipe supply company is Vallourec SA, a multinational manufacturing company headquartered in Meudon, France which specialises in hot rolled seamless steel tubes, expandable tubular technology, automotive parts, and stainless steel, which it provides to energy, construction, automotive, and mechanical industries.
“They were milled in Brazil, coated in Brazil, and were brought over here. They have to meet certain international standards. They are also seamless. Imagine a complete solid cylinder and they extrude it with a tool inside of it and on the back of it comes out all these steel and that is how they make pipe. The pipeline is made of carbon steel and you normally have a coating system, an external coating system, that protects it from the environment… the coating system is what allows it to have a long lifespan. If you allow it to just be in carbon steel it would just corrode, but with a coating system it wouldn’t,” Krispin explained.
“We concern ourselves more about internal corrosion than external corrosion because the coating protects it from external corrosion, and being under water, because there is no oxygen, there is no corrosion. Corrosion has to have oxygen, even with salt. You put a piping on the sea bed and it wouldn’t corrode with the exterior. It will corrode internally if you let water go through it or liquids go through it and that is why we have a liquid maintenance system that cleans the pipeline so often and we maintain gas, in the gaseous form to make sure we don’t get liquids inside the line,” he added.
Underwater
And with fears by many that the pipeline will be underwater at great depths and thus a leak would not be identified until a possibly serious incident occurs, Krispin assured that internal corrosion is also monitored given technological advancements where monitoring is done remotely.
“How do we know if the insides are corroded? There is something we call a PIG (pipeline integrity gauge). It is a tool that you run inside of the pipe. Normally you have a maintenance pig that you run to clean up the liquids and that pushes the liquids out, whatever the liquids may be. The second one is an intelligent PIG; a PIG that has like little fingers on the perimeter of it. It uses this as a technology to read the pipe. We push this from onshore to offshore and for every millimeter, it reads the thickness,” he explained.
“All that data goes into a computer and it tells you if you have some degradation of thickness. Those are the ones we use… to know how much more pipe do we have, so we need to go in there and repair it or do we have time to let it go and check it again in six months, et cetera,” he added.
It is this pipeline integrity management system that will be relied upon to keep the pipes clean and monitor the entire perimeter or thickness of the pipe.
Depending on the phase of the pipeline installation process, the company uses different technologies, but most of the time we will bring the pipe in joints and put it on the vessel and then have a pipe-laying vessel with an automated system where you weld it together and do non-destructive testing to determine if the weld is good. And if it has any fissures or microscopic tears in it, it isn’t accepted and it is cut off and welded again “to get to that perfect weld.”
And even after welding on the vessel, an ultrasound testing is done. “You coat that again and have the same as the rest of the pipe and you push it… and so on and so forth” as the vessel moves during the process.
The big vessels that are laying the pipes can do a couple of kilometers per day of pipe.
“It is a very automated system… where they back out as they are laying pipe in the sea. The vessel works on GPS system. The route has already been determined. The vessel stays on the GPS route. They run 24 hours, a crew that works during the day and one which works during the night. They stay and sleep on the vessel,” he explained.
For the first 75 kilometres, the pipe is buried to protect it from the users of the sea so they wouldn’t run an anchor on it… so it is anchor proof. For that area, major tankers cannot anchor in as it is too shallow.
There are several phases of the laying process and as there is simultaneous laying offshore and onshore. At one point “they will pick up both sides and lay them back down in an “above water tie in” process.
Seawall integrity
ExxonMobil wanted to allay concerns of the seawall integrity being compromised so much that the company said it chose to lay the pipe under the seawall instead of cutting it and running the pipe through. “You like your seawall and want to be protected from the sea. We did not want to do anything that could undermine the integrity of the seawall. If you put the pipe on top of the seawall, you expose the pipe to people driving on top of the seawall or vessels getting too close to it or whatever. The best way to run that would be to actually cut the seawall or you go under. We looked at cutting the seawall and decided against it because of that whole issue of undermining the integrity of the seawall, even though you will close it back up. There is also the concern of the communities – you know, you are cutting my seawall,” Krispin explained.
“What this system does is you actually put a drilling rig that sits here on land and they drill under the seawall. The point that they cross the seawall is about 30m deep and it goes way under and comes back out 80 metres later, way, way offshore. In that way, you will never see that pipe in there. It is deep, deep in there. It costs more but in that way the seawall maintains its integrity. When it gets out, it grabs the pipe and brings it back. There wouldn’t be any water coming back in or water going back out and it wouldn’t move,” he added.
The pipeline will be preserved for the lifespan of the field and Krispin noted that “pipes have been there for 50 years if you treat them properly and keep them clean.”
Meanwhile, on land, safety features are just as rigid. “We have a ROW [Right of Way] on the land that has been given to the project to put the pipeline in. The ROW is 25 metres wide, the pipe is in the middle of it and is buried so you don’t see it. Landowners that used to own land where that ROW is don’t own that land anymore. They cannot farm that land anymore, burn that land anymore. They cannot till or bring a tractor or backhoe or anything like that.”
On Tuesday March 19th, the company told residents that among pipe-line safety plans, after the pipeline becomes operational, ExxonMobil Guyana Ltd (EMGL) will utilise various methods to proactively respond to possible integrity issues in its systems before safety and environmental performance is compromised.
There is also a fibre optic cable that runs alongside the pipe and it “senses if there is any kind of disturbance on top of the pipe or digging any driving of major equipment, anything like that and it notifies the operator. It sends a signal that there is a problem there. So if somebody happens to be digging in there, the operator will be notified,” Krispin explained.
At the March 19th event, the company stated that “Aerial and ground based inspectors will regularly monitor the pipeline route for potential integrity issues including, but not limited to, visible changes to the soil and vegetation that may indicate a leak, unauthorised access or activities, or obstructions that could affect maintenance, inspection or repair operations, and depth of cover.
ExxonMobil says that the natural gas pipeline project is the first of its kind here, “but is unlikely to be the last, as Guyana continues to expand its economy.”
It was highlighted that the community was important to EMGL and as such, it is pleading with persons to get engaged.
“At EMGL, we believe in continuous engagement with the community to answer questions and address concerns. We welcome you to utilize our Community Grievance Mechanism (CGM) to raise concerns directly to EMGL and have them addressed in a prompt and respectful manner,” the pamphlet states. It lists a 623-1176 telephone number and an email address, guyanancommunity@exxonmobil.com to contact for complaints and concerns.
The company lists a number of Do’s and Don’ts. Among the Do’s are for persons to respect the Right of Way (ROW), the narrow stretch of line which the pipeline follows. It also asks that they look out for signs and pipeline markers, call the emergency numbers if there is an emergency, warn others of the presence of a gas line in the area and to report any strange activity near or on the ROW to EMGL.
The Don’ts are that persons not remove signs or pipeline markers, prank call emergency numbers, plough, dig or flood the ROW, build or erect structures, bridges, pathways, or stockpile materials on the ROW. They should also not run cables or drainage pipes over the ROW or burn within the ROW or allow their cattle or other animals to graze on the ROW.
Overall, ExxonMobil believes that the project is a great one and with the safety systems in place, citizens could be assured that all will be well, and if in the unlikely event there is any leak indicated, the company has the capacity to correct it in the swiftest time possible.
