Flow assurance: Vital to a successful supply chain
While pipeline operators and engineering companies continue to look for ways to not only remain safe and compliant, but also optimize operations, flow assurance continues to be a vital topic. Coined by Petrobras in the 1990s, flow assurance simply means ‘guarantee of flow’1. It encompasses the entire supply chain of the hydrocarbon industry, from source to end-user.
Here we look at the key challenges of flow assurance and how technology like pipeline simulation helps us understand the impact on operations by modeling outcomes.
We will look at:
- Overcoming flow assurance challenges and optimizing operations
- How technology like pipeline simulation helps
- Modeling the risks and optimization
- What is surge analysis?
Overcoming flow assurance challenges and optimizing operations
Interruptions to fluid and gas flow are not only costly to pipeline operators, but also safety concerns. There are a few key challenges associated with flow assurance that a pipeline simulator can help with, as well as areas it can help to optimize your operations.
- Predicting future trends to optimize operating schedule
- Looking at unplanned events (such as compressor outages) and how they can be managed
- Training new and existing control room staff
- Developing start-up and shutdown procedures
- Optimizing the transition to green energy
The consideration of the energy transition is an important area for most. Pipeline operators need to understand how the transition to hydrogen for example will affect the pipeline capacity. It’s expected that many natural gas pipelines will be repurposed for hydrogen blends, so it’s crucial to understand how this infrastructure will cope. Pipeline simulation that is capable of accurately modeling different blends of hydrogen can be used as a powerful decision support tool, removing areas of guesswork and uncertainty.
How pipeline simulation technology can help
The role of a flow assurance engineer in a project is to provide predictions, prevention strategies and remediation methods to factors that might jeopardize security of supply7. These types of engineers are involved across the project lifecycle, from concept to front-end engineering and design (FEED), to commissioning and operations support.
Flow assurance engineers often use a pipeline simulator to carry out detailed analysis of the pipeline at all project stages. This can be completed for both transient and steady-state conditions offline. Since hydraulic simulators mimic the pipeline systems it presents a virtual view of the pipeline during normal and abnormal operating conditions.
During the design phase, a pipeline simulation can be used by flow assurance engineers to explore various approaches to meet the intent of the design. Studies like this can cover a wide range of scenarios including5:
- Flowsheeting - Laying out the network and finding operating conditions
- Design specification - Selecting appropriate pipe material or equipment from vendors
- Control philosophy - Defining a narrative for how best to operate
When the pipeline is in operation, a simulator can be used to assist with factors that are a key concern of flow assurance engineers like interpreting flow hydraulics, flow characteristics and thermal behaviors, also assisting pipeline control room staff with routine and ad-hoc tasks. This means pipeline simulation helps with flow assurance by offering5:
- Troubleshooting - Identifying issues and overcoming them
- Predictive analysis - Anticipating disruption and avoiding it
- Operations planning - Especially modifications to fluids and flows
- Expansion studies - Assess the retrofits involved in a proposal
- Operator training - Demonstrating their competency to regulators
- Optimization - Finding the best strategy or debottlenecking capacity
Modeling the risks
There are several scenarios where pipeline simulation can be used to model flow assurance risks. Where energy transition is concerned for instance, a simulator can be used to model how the pipeline infrastructure will cope with hydrogen blends in the system.
A tool like Atmos Simulation (SIM) Suite can be used to answer important questions around capacity constraints, how to cope with unplanned events like compressor outages or supply failure.
Using the look-ahead function of Atmos SIM, the model runs faster than real-time to tell you what will happen in the future and warn pipeline operators of any operational or contractual violations that would occur in the future unless the current operational plan is modified.
Optimizing operations
As well as managing the associated risks, pipeline simulation can also be used for optimization. Many Atmos clients are currently using the look-ahead function to optimize operations as follows:
Predicting the future pressures of gas pipelines based on demand, production and compressor operation up to 48 hours into the future. This allows pre-validation of capacity to deliver nominations and gives the controller details about when and where there could be operational issues so preventative action can be taken well in advance. In addition it could identify the most economic option while meeting all nominations.
What is surge analysis?
Rapid transients are a specialist area of liquid pipeline management, they involve changes happening in very short timescales5. Surge analysis works to simulate rapid transients such as surges in pressure. Analysis like this can be very demanding and time consuming due to the thousands of miles of pipeline that needs to be analyzed. Some authorities require pipeline operators to have up to date surge analysis studies, the US Department of Transport (DOT) for example.
The benefits of carrying out surge analysis using Atmos SIM include:
- Leak prevention with locations where operation is likely to cause a rupture identified
- Saving time through the automated process
- Precise data collected and presented in a graphical view
Tools like Atmos Surge Analysis, a module that is included in Atmos SIM works to make the process of performing a surge analysis faster, and easier, simplifying and automating the process of submitting a detailed report to the relevant authorities. It schedules the running of a series of scenarios such as valve closures and pump trips, with the data for each analyzed for pass and failure criteria. This data is then entered into a report, where it is displayed graphically in trends. The report locates maximum pressure points and pump trip times.
Performing surge analysis regularly can help prevent pipeline incidents thus assure the pipeline is safe to deliver the flow required.
Flow assurance with pipeline simulation
As a wide-ranging term, flow assurance spans the entire supply chain of the hydrocarbon industry, from source to end-user. Pipeline simulation is becoming an integral part to handling some of the key flow assurance challenges.
Although there are some areas outside of its control, pipeline simulation can be used to answer key questions around the infrastructure, what if scenarios and deeper insights like surge analysis. It can be used for the entire lifecycle of the pipeline, from FEED, to commissioning and while in operation. Being able to carry out these simulations is of vital importance to pipeline operators to understand the health of the infrastructure, answer questions and optimize their operations.
References
1https://www.oilandgasiq.com/oil-and-gas-production-and-operations/news/what-is-flow-assurance
2https://www.usgs.gov/faqs/what-are-gas-hydrates
3https://www.witpress.com/Secure/elibrary/papers/MPF11/MPF11022FU1.pdf
4https://www.eu-midas.net/science/gas-hydrates
5”The Atmos book of pipeline simulation”
6http://impact.nace.org/economic-impact.aspx
7https://www.crondall-energy.com/post/blog-what-does-a-flow-assurance-engineer-do