Read the full EPRS article in August 2020 issue of World Pipelines.
Authored by James Rowley, Market & Business Development Director, Connector Subsea Solutions.
For an Emergency Pipeline Repair System (EPRS) to be effective it must be “fit for purpose”, but what does this actually mean? What is “fit for purpose” for one operator or one pipeline, may not be for suitable for another.
The simple answer to this question is “a system that is able to deliver what is required, to the specification required, in the right timeframe and in the right location.”
It sounds straightforward, but in reality, the process of selecting the right EPRS is incredibly complex, with multiple environmental, technical and operational factors to be considered, not to mention quality, reliability, delivery and cost. One of the major factor multipliers is pipeline diameter as not only does this impact size, weight and cost, but it has a direct knock on impact on material forging specification, subcontract supply route and ease of inspection, maintenance, mobilization and installation.
EPRS is a significant investment, so how do operators make sure they get a system that is right for their pipeline?
Assessing the Risks – Probability, Cause & Impact of Failure
Whether onshore, topside, subsea or in deepwater, every pipeline in the world is at risk of failure. Pipeline operators face vastly different challenges and are willing to accept vastly different levels of risk. An acceptable level of risk for one, may not be acceptable for another, which makes commercializing a system or process that will enable the repair of a pipeline in an emergency a significant challenge.
An EPRS exists to mitigate the risk identified to pipeline failure by offering a method of repair that significantly reduces the potential cost. The simple formula of Probability x Cost = Risk underpins the decisions made by most pipeline operators about the level of risk that exists and informs their decisions about their level of investment in EPRS.
To successfully develop a fit for purpose EPRS the pipeline operator must first identify which assets they consider to be at suitable risk to warrant investment. At this stage, dialogue between pipeline operators and equipment manufacturers can get underway. Given the vast array of EPRS options available, early discussions are essential and can lead to front end engineering studies to provide a mobilization schedule vs price options. Material specifications, testing requirements, storage locations and maintenance schedules all need to be explored before a comprehensive EPRS can be initiated.
Corrosion and erosion are often cited as major contributing factors to pipeline failure, but the risk to pipelines caused by geography or operating environment also need to be considered. Dropped objects and dragged anchors are a particular risk near ports and harbours; when hot fluid first traverses a flowline that is initially at ambient temperature the resulting expansion can cause the pipeline to walk and fatigue; in some geographical locations sabotage may be a real threat.
However, it can be too easy to dismiss this risk based on probability of occurrence. The likelihood of a specific pipeline failing due to a single incident is incredibly low and therefore mitigates the need to have a planned response – until that particular asset is bundled with many other assets, and the consideration expands to include the pipeline length and duration of field service, many lasting a minimum of 25 years but with field upgrades, potentially up to 35 or 40 years.
As the margin of extremely low probability reduces, a second consideration arises: the cost of pipeline failure. There are many costs that are easily quantified for example the cost of repair equipment, mobilisation time, service costs, downtime and lost production. Not only are they relatively easy to estimate but cost multipliers can be applied for increased pipeline diameter or pressures, however there are other costs that are much harder to quantify. Injury to personnel or loss of life, environmental damage, impact on the commercial value of a business, litigation, all of which are incalculable as an allowable projection.
Key Considerations for Investment Decisions
The main consideration is where the repair is likely to be required and in what timescale does it need to be mobilised. Before a repair can be conducted the damaged area needs to be inspected, the root cause identified and addressed, and a suitable repair planned. Even in an emergency this can take time, more so if the repair is required in an isolated location or subsea. A repair that is required onsite within 24 hours is only possible with a fully built system that is tested, maintained and located within a local radius. A repair that is less urgent and is required in 6-8 weeks not only frees up the location of storage but limits the amount of hardware required to be on standby readiness. In these situations, stocked raw materials and a pre-approved supply chain may suffice.
Another consideration with any EPRS is the amount of capital expenditure an operator is willing to invest, to what in essence is an insurance policy. Having fully built, maintained and locally stored equipment is not only expensive to implement but has a high running cost to ensure the equipment and service engineers remain primed and ready to mobilise at any time.
These costs can be mitigated through extending the lead time of mobilisation and reducing the EPRS equipment to stored material only, or by sharing a pool of EPRS assets with other operators. Connector Subsea Solutions established an EPRS Club in 1995, and currently has 10 operators as members, who have access to quality equipment with options for all pipeline repair products, all of which is stored and maintained in a secure facility.
With every decision there is a risk vs reward consideration. Sharing assets will reduce your capex and opex but should another operator in the group need the equipment to be mobilised, your assets will remain unprotected until a replacement system is built and reinstalled.
In most cases critical infrastructure – major export pipelines or trunklines – are considered of suitable risk to require an EPRS. Typically of large bore, the risks are higher should something go wrong, both in terms of the volume and value of the oil or gas being transported. There is the potential for a catastrophic safety event, significant environmental damage, financial implications for the pipeline operator, and the impact any interruption would have on a country’s energy supply.
An example is the Brent pipeline in the North Sea. A 36” pipeline transporting 100,000 barrels of oil per day, the pipeline transports oil from 20 different fields and has 21 different owners. Since 2004, a pair of 36” MORGRIP® Repair Connectors have been on standby in a fully built condition ready for mobilization within seven days in case damage occurs.
In 2011 an unexploded World War II mine was discovered dangerously close to the pipeline and in 2015 a valve replacement was scheduled where a contingency repair was required to be available on the vessel in case issues occurred. In both scenarios, mobilization of the EPRS was not required, but for critical infrastructure like Brent, this standby option is essential. Like an insurance policy for your home or your car, you hope you never need it, but you would not risk being without it in the event that something goes wrong.
Challenging Environments Drive Innovative Solutions
As field developments venture into increasingly challenging environments, increased depths, pipeline pressure, diameters and complex well fluid drives the innovation of new repair techniques.
Western Australia, Brazil, West Africa, East of India and Gulf of Mexico, to name a few, operate in deepwater. Most diver repairs can be achieved safely in water depths up to 150m, but when operating in depths from 150m to 2000m, full ROV-operated remote systems are required. These systems were first developed in the Norwegian Continental Shelf deploying remote connectors for pipelines up to 30” and remote welding from 30” upwards. It was believed that 30” diameter pipes required such large connectors that the means to mobilize and deploy them would be commercially and operationally challenging. However, in 2015 a Western Australian operator invested in their own deepwater pipeline repair system, implementing MORGRIP® remote connectors for 36”, 42” and 44” pipelines.
The remote systems require tight constraints on the many different interfacing components – not just the interface between the connectors and installation frames, but the interface between the pipe and connectors, and the frames and seabed. A much more holistic approach is required to address each challenge in turn. For this reason these remote systems are always fully build, assembled and tested prior to being implemented as an EPRS.
Well fluids create an additional challenge for EPRS. If an oil or gas contains high concentrations of CO2 or H2S (Sour) the media can be highly corrosive to carbon steel. In order to transport it safely different materials must be used, typically stainless steel, duplex or a carbon steel pipeline with a corrosion resistant alloy cladding or liner. To ensure a permanent repair with no damage to the parent pipe, the repair solution, whether clamp or connector, needs to be fabricated from the same material as the pipeline. A carbon steel connector cannot be used on a duplex pipe without a significant risk of galvanic corrosion occurring, so the EPRS must be adapted to accommodate a change in component specification, which brings an increased challenge in how it is stored. Duplex material should not be in contact with carbon steel material as the risk of carbon migration exists, so isolated storage and maintenance is essential.
As the industry continues to push boundaries, there will be new challenges ahead that none of us have even encountered yet, and the supply chain will have to work hard to come up with new solutions. Technical, commercial and contractual innovation will be critical in ensuring EPRS continue to keep people, the environment, and operations safe across the world.
As an EPRS provider and the owner of MORGRIP, Connector Subsea Solutions champions solutions that are based on our core design philosophy of promoting lightweight, reliable and innovative solutions.