Leak detection in the face of challenging pipelines
While a pipeline might seem linear on the surface, monitoring for leaks on some pipeline networks is not always a straightforward process.
Pipeline networks in African, Canadian, Latin American and Middle Eastern countries can run through remote areas and have a weak infrastructure, creating challenges for the deployment of leak detection instrumentation.
Pipelines in the vicinity of high consequence areas (HCAs) and moderate consequence areas (MCAs) run the risk of causing extensive damage to surrounding areas during a leak event, as well as resulting in fines for the offending pipeline company, making fast and accurate leak detection a necessity.
The increased use of multiphase flow in pipelines creates a challenge for leak detection due to the complex and variable hydraulic conditions and difficulty in retrofitting leak detection hardware or equipment on operational pipelines.
Increasing pressure to reduce carbon emissions and protect the environment, particularly in light of world leaders at COP28 committing to accelerate the energy transition,1 means leak detection on all pipelines has never been more critical, but high consequence areas, multiphase and remote locations can present challenges for the installation of leak detection solutions.
Pipelines operating in HCAs, multiphase or in remote locations will be discussed in this blog, with Sales and Senior Research Engineer Harry Smith presenting improvements to leak detection hardware and software that can overcome these challenging pipeline monitoring scenarios.
Pipelines in high consequence areas (HCAs)
HCAs in the US pipeline industry are understood as locations where a leak or rupture would have a significant impact on the health and safety of the surrounding area2 and typically achieve this classification based on the number of buildings, facilities, outside or open structures in the vicinity of a pipeline section.3
A leak or rupture in an MCA can cause lots of damage too even though they represent locations with lower risk than a HCA. MCAs typically contain some buildings, but less than in a HCA, or contain a portion of an arterial roadway with four or more lanes.
Leak detection that optimizes sensitivity is vital in reducing the impact of a pipeline leak, rupture or explosion on a HCA or MCA.
The emergence of the combined approach to leak detection means it’s possible for operators of pipelines in HCAs and MCAs to have access to a solution that’s highly sensitive and with accurate leak location.
For example, Atmos Wave Flow utilizes statistical corrected volume balance and negative pressure wave methods to reduce uncertainty in a leak detection system and improve performance. This combined approach was used to support Rotterdam Rijn Pijpleiding’s longest pipeline.
Read the case study Discover Atmos Wave Flow
Upgraded algorithms
Upgraded algorithms can also improve leak detection in areas of high risk like HCAs and MCAs where sensitivity is critical.
Atmos has been working on a new algorithm for its leak detection solutions. This leak onset detection method can be used as an additional leak detection alarm, providing an added level of protection.
A deterministic meter correction paired with finite impulse response filter ensures it is always searching for the smallest change (increase) in the difference between the current average flow difference and the historical flow difference in each pipeline fluid.
The high sensitivity is achieved without increased false alarms as it identifies transients and density changes automatically and deactivates during these transient periods. The below algorithm has demonstrated a significant reduction in the leak size detectable from 14m3/h to 2.2m3/h.
Figure 1: The new algorithm alarmed for three separate incidents of product theft on a UK pipeline company’s network (red bar in the top chart indicating leak/theft alarm)
Multiphase
With variable fluid composition and flow rate in a multiphase pipeline, a challenge facing multiphase leak detection is the complex and variable hydraulic conditions. There’s also a feasibility issue of retrofitting leak detection hardware and software on operational multiphase pipelines, paired with high cost and poor performance of flow meter instrumentation. However, recent developments demonstrate possible improvements to the process of implementing leak detection on complex multiphase pipelines.
Example pipeline: onshore multiphase
A customer faced two challenges on its multiphase NPS 6 pipeline: the variable composition of oil and gas being transported in the pipeline and the pipeline’s route passing under a river. River-crossing pipelines present a challenge for effective leak detection due to the sharp elevation change involved.
This particular pipeline was only 3.7 km long but the elevation change of the pipeline was 70 m as it passed under the river, causing changes in the flow regime along the pipeline. This made the development of a leak detection system without individual component metering a challenge and a mass flow balance method impossible.
Figure 2: The elevation profile of the onshore pipeline with 70 meter drop at the river crossing
This pipeline transported a mix of gas and liquid at different flow-rates so the flow regime varied between churn flow, elongated bubble and slug which is one of the most challenging regimes for effective leak detection.
Installing additional pressure sensors enabled the leak detection algorithm to determine whether negative pressure waves were leak events or caused by operations. Leak trials with different sizes confirmed that a negative pressure wave system would be able to detect the majority of leakage while maintaining a low false alarm rate.
To improve the sensitivity further the leak detection system was optimized to reduce the minimum detectable leak size. This was achieved by the additional field instrumentation, optimized pipeline operations and the inclusion of an inline inspection tool.
Figure 3: Cleaning pig with the inspection tool attached
The findings were that a real-time negative pressure wave system can provide effective leak detection coverage on river crossing sections of multiphase pipelines without false alarms, the inline inspection tools such as the ones offered by Atmos can detect small leaks offline that an online system may miss.4
Read the full case study Learn how Atmos supports multiphase pipelines
Remote locations
Pipelines commonly run through remote locations because the planning for pipeline routing typically requires pipelines to avoid contact with surrounding communities and areas of cultural or environmental significance.5,6 However, this not only means that large sections of pipeline networks in the world are in areas where visibility for pipeline operators is limited, but these pipeline sections are at more risk of weakening and leaks occurring.
Latin America
Latin America’s physical geography comprises of coastal plains, highlands and mountains and river basins,7 so pipelines are vulnerable to the geohazards associated with the region. For example, riverbed scour and the erosion that follows has resulted in three rupture oil pipelines in Ecuador, resulting in approximately 57,000 liters of lost oil.8
Middle East
Desert land makes up over 80% of the Middle East, so it’s nearly impossible for a pipeline to avoid remote locations in the region. The Habshan-Fujairah Pipeline is 380km long and transports crude oil across deserts and mountains. This presents challenges such as a lack of power for instrumentation and the mountains can weaken pipeline integrity in the event of landslides, causing more leak events.
Updates to leak detection technology in remote locations include non-intrusive hardware instrumentation like Atmos Eclipse that can be retrofitted to pipeline sections and measure flow, pressure and temperature for leak detection.
In areas where access to power and communication is limited, Atmos Eclipse can be powered by wind and solar energy for zero downtime, collecting leak detection data continuously for analysis. For remote locations with significant elevation changes, such as pipelines with slack flow in mountainous areas or river crossing, this hardware instrumentation can be configured to detect leaks.
Figure 4: Atmos Eclipse can collect data on pipelines in remote areas where there is high elevation (left), long distances with limited instrumentation (middle) and short pipelines crossing rivers (right)
Only effective leak detection can overcome challenging pipeline scenarios
Pipelines involving HCAs, MCAs, multiphase and remote locations present a range of obstacles for effective leak detection, however the consequences of leakage in any of these pipelines can be more devastating than in other pipelines.
Recent improvements to leak detection in these contexts prove that effective pipeline monitoring is possible for such pipelines. An effective leak detection system comprising of hardware and software is vital in challenging pipeline scenarios.
For more updates on leak detection improvements in challenging pipeline monitoring scenarios, download our paper in full, which was first presented at the Pipeline Technology Conference 2024.
References
1 https://unfccc.int/sites/default/files/resource/Summary_GCA_COP28.pdf
2 https://primis.phmsa.dot.gov/Comm/glossary/index.htm#HighConsequenceArea
7 https://education.nationalgeographic.org/resource/south-america-physical-geography/