For our last post, I think it is important to show how pipelines are installed in the sea and subsea. As with all other posts, the focus area will be on the Arctic North region around Russia and Norway. Mentioned in post 2, Icebergs are just the tip of the… well… Iceberg. There are two major concerns with installing subsea pipes in this region; icebergs and diapirs. In this long blog post we will investigate current methods for installing pipelines and some proposed methods for installing pipelines in the more difficult regions of the Arctic North.
The subsea pipeline industry over the past few years has developed and grown into a multi-billion dollar industry. There has been significant development towards safety of pipelines and reduction of costs for installation and maintenance. To meet new business challenges associated with larger water depth and with the transportation of aggressive and unprocessed fluids over long distances, the industry has responded with new pipeline concepts based on corrosive resistant materials, enhanced thermal performance and heating technologies (INTSOK – Norwegian Oil and Gas Partners, 2014). These methods are currently being qualified and successfully implemented around the Earth. Subsea pipelines will be a major building block in the development of gas and oil fields in the Arctic North and are considered to be efficient for transportation of oil and gas to offshore hubs, to onshore processing/storage facilities or into existing transport networks (INTSOK – Norwegian Oil and Gas Partners, 2014). Because of the harsh environment and the low temperatures in the High North there will be a need for additional pipeline requirements upon both fabrication/installation and operation which in turn means more costs. One other consideration for the project is the need for enforced steel materials and coatings able to resist low temperatures, pipeline systems in the High North have to be designed for potential load conditions caused by direct or indirect ice interaction (INTSOK – Norwegian Oil and Gas Partners, 2014).
Current, Current, Current
Design, installation and operation of pipelines
There are a few pipeline standards and industry considerations that are currently being considered for the project. These include:
· DNV-OS-F101 Offshore Standard – Submarine Pipeline Systems
· ISO 13623 Petroleum and natural gas industries – Pipeline transportation systems
· API RP 1111 Design, Construction, Operation, and Maintenance of Offshore Hydrocarbon Pipelines (Limit State Design)
(INTSOK – Norwegian Oil and Gas Partners, 2014)
The DNV-OSF101 offshore standard has been the top pick for the project at its current state. The DNV standard is intended to comply with ISO 13623. This means that the design format is based on risk and reliability principals, which are implemented based on defined limit states and corresponding partial safety factors. This standard gives recommendations for the design, materials, construction, testing, operation, maintenance and abandonment of pipeline systems used for transportation in the petroleum and natural gas industries (ISO, 2017).
How the pipeline is built while at sea is shown in the fun video below provided by Allseas.
Video can be found here: https://allseas.com/activities/pipelines-and-subsea/pipeline-installation/
This method of pipe laying is the S-lay. This would be used in the locations of 1, 2 and possibly 3. Shallow water is required so that there is not too much tension on the pipeline as it is being laid. The pipes can be between 2” and 48” diameters. This installation is preferred as it is faster than the J-lay method. The pipe is able to be welded, inspected, coated all aboard a pipe laying vessel, such as the one above (Allseas, 2019). The first step is to transfer the pipes to the floating factory. From there the pipes are preheated at the ends, then welded together for the first time. After that they are welded further and have a welding cap installed on the joints. The next step is to test the pipe for leaks with an automatic ultrasonic tester. This will make sure there are no issues in the before it is dropped into the ocean. The final step is to install a joint cap or a special coat that will ensure that the joints do not fall apart or rust from being in the water for long periods of time. As the boat moves forward, the pipe is laid behind it and placed on the seafloor. The next step is the digging of the ground and burying it underground.
Burying the pipes underground is critical in the Arctic North, as mentioned before, icebergs are able to destroy pipelines if they are above the scouring depth. How the pipe is buried underground is shown in the figure below.
Figure 1 – Rover installing sub-sea pipelines (INTSOK – Norwegian Oil and Gas Partners, 2014)
The High North project is investigating the use of rovers to install the pipelines. This rover, would be digging underground, laying the pipe in the hole and then covering it at the same time. It will also be able to monitor possible diapirs that are around and avoid them should they be in the way. Additionally, they team will be developing a new system for monitoring iceberg drifting and sizes in the areas with the pipeline exists so that they can safely and effectively operate the oil rigs in extremely remote locations. There currently are no recognized iceberg sizes that can be used as a design load for wellheads, pipelines, process equipment and guidelines for design and handling of any incidents should they develop (INTSOK – Norwegian Oil and Gas Partners, 2014). They will be creating a new method to control the flow of icebergs as more and more will be moving due to climate change. The team considered multiple options during the installation process for the protection of pipelines in soft soils, where trenching is not possible. These areas may require additional resources such as concrete mats, which will help protect the pipelines from scouring and damage from icebergs. An image of the pipeline concrete mat is shown in figure 2 below.
Figure 2 – Concrete mattress on top of a pipeline (retrieved from OE digital)
Inspection, Maintenance and Repair (IMR)
The final step of building pipelines is the inspection, maintenance and repair.. Because the location is remote with limited access, the project needs to be carefully planned. The system must be able to adopt or evolve to changes within minutes, should there be a leak to prevent from catastrophic failures. There will be a large delay between when a problem occurs and when the teams are able to respond, so mitigating the risks in the first place is critical to pipeline planning and installation. Currently, the large extent on pipeline installation is based on corrective maintenance, meaning they will fix a problem as they arise (INTSOK – Norwegian Oil and Gas Partners, 2014). This will not work in the Arctic north, as time may be as long as weeks before it can be fixed. There has always been a philosophy of limited number of sensors on the equipment because it has always been extremely costly, but the trend now is to increase the number of sensors and then the amount of information that is possible to retrieve from equipment (INTSOK – Norwegian Oil and Gas Partners, 2014). This will allow oil well operators to best monitor the slight changes in the environment and adapt to the climate. It, in turn, could possibly decrease the total damage to equipment and the threat to the environment. One key factor that the High North group is considering is the use of autonomy and computers to run systems. With computers, the system will be able run 24/7 and will require minimal labour. This means that there will be limited liability to human safety as there will be no humans on board or nearby. This is favourable not only to the company but also the humans, as there is a less threat to their lives.
The final consideration the team is looking at for the pipeline is the life extension of it or the abandonment. If it becomes economically feasible to lay pipeline in remote and challenging places, the current system will system will need to be modular and flexible. The High North project will be looking to standardization equipment, practices, communication and connection between the oil companies and the equipment vendors (INTSOK – Norwegian Oil and Gas Partners, 2014). This will help to keep all pipelines usable and extent life of them for many years. The expected typical design life today is 25 years, but the team is looking to extend the initial design life of the project even further.
Overall, the High North project will be an intense project with a multitude of factors to consider. The installation of the pipelines can be completed easily and with the development of new technologies, hopefully they can be installed easily into new Northern regions.
Thanks for reading my blog and hope you learnt lots!
Allseas. (2019). Pipeline Installation. Retrieved 03 13, 2019, from Allseas: https://allseas.com/activities/pipelines-and-subsea/pipeline-installation/
INTSOK – Norwegian Oil and Gas Partners. (2014). Russian – Norwegian Oil & Gas industry cooperation in the High North. Skoyen: INTSOK.
ISO. (2017). Petroleum and natural gas industries — Pipeline transportation systems. ISO.