March 2022, Vol. 249, No. 3
Features
Geo-Hazard Challenges and Mitigations for Hydrocarbon Pipelines
By Girish Babu Nounchi, Senior Pipeline Engineer, Branko Davidovic, Lead Pipeline Engineer, and
Dimitris Nychtarikas, WOOD PLC, and Palash Sanyal, AGM Pipelines
Routing hydrocarbon pipelines through steep terrains and along high mountainous areas is a challenging task for pipeline engineers because of significant risks during the construction phase, as well as operation and maintenance time.
Applying standard principles to meet the project requirements may or may not be adequate. If requirements are not fulfilled, there could be chances of failure, which may cause huge losses to the operating companies in terms of revenue, schedule, customer demand, environmental impact and the company’s reputation.
Special engineering designs for foundations or slope stability is mandatory because pipelines cross different types of geomorphologic regions, such as hills, rivers, soft soils and colluviums deposits. Laying and operating pipelines in such inaccessible sloping areas involve significant risks in terms of geohazards. Criticality varies with respect to the nature of terrain, accessibility, presence of water flow channels, slopes, etc.
Once geotechnical studies have been performed, the availability of required construction equipment and experienced construction professionals, as well as implementation of proper quality control measures are additional benefits to the operating companies and the engineering, procurement, and construction (EPC) contractors.
Studies on slope stability, soil erosion, rock slip and water flow velocity, by considering previous year’s data, help pipeline engineers make critical decisions while selecting and designing the route, drainage patterns, slope cuts and wadi crossings.
Such studies not only minimize the risks during construction, but the studies also help to avoid problems with pipeline integrity during the operational life phase. In case of transmission pipelines (oil and gas), statistics show the main causes for pipeline ruptures are corrosion and third-party action. Pipeline damage statistics from Canada, Europe and the United States indicate that about one-eight of all pipeline damage incidents over the last 30 years have been due to geotechnical hazards.
Ruptures caused by geo-hazards are less frequent; however, the damages and consequences can be higher in comparison with other pipeline failures. The cost in terms of money incurred from geo-hazards are almost double than other hazards.[1]
Geo-hazard ruptures can cause gas to ignite, severely damaging gas transmission lines in the surrounding areas. In the case of hydrocarbon liquid lines, there also may be severe environmental impact due to the leakage.
To reduce the geological and geotechnical risks, preventive actions should be studied from the design phase and recommendations from the subject matter expert (SME) must be implemented.
Corrective actions must be taken without any delay in case there is a chance for rupture/damage after construction. This article discusses the geo-hazard challenges, special studies, design considerations and mitigation for hydrocarbon pipelines.
Pipeline Geo-Hazard Risk Management Program (PGMP)
In accordance with ISO-20074, “Geo Hazards Risks shall be identified, proper assessment and mitigations measures shall be carried out by qualified persons throughout pipeline life cycle.”
PGMP helps make sure the pipeline is environmentally responsible and operates reliably using preliminary engineering, detailed design, construction and operation practices.
Preliminary Engineering and Detailed Engineering Phases
Preliminary engineering and detailed engineering phases are the two phases recommended to avoid the geologically sensitive and vulnerable areas, while selecting the route and rerouting the pipeline.
Pipeline engineers will consider the below-minimum routing factors (based on overall routing considerations specified in ISO-13623 and Annex-A of ISO-20074). Pipeline routing selection is highly constrained by economic, environmental, geotechnical and physical factors, which severely curtail route options.
By clearing vegetation, personnel can easily identify new, undetected geo-hazards.
Also, heavy machinery potentially can create additional geohazards, such as steep cuts, unconsolidated spoil and fill areas. Once the pipeline is installed, it is recommended that the ground and pipeline corridor is monitored to avoid major damage to the pipelines.[2]
In unavoidable situations, the following design considerations and mitigation techniques are beneficial to engineering based on the following geo-hazard classifications.
Conclusion:
Geo-hazard studies must be carried out by SMEs, and their recommendations must be respected in view of pipeline integrity and environment safety.
Engineering consultancies must record and maintain the case studies on geohazards so operating companies can take necessary actions based on PGMP risk levels.
References:
Dharma Wijewickreme, “Role of Geotechnical Engineering in Assuring the Integrity of Buried Pipeline Systems” Scientia Iranica A 23, 4 (2016): p. 1658-1674.
ISO-20074, “Petroleum and natural gas industry — Pipeline transportation systems — Geological hazard risk management for onshore pipeline” (Geneva, Switzerland: International Organization for Standardization).
ISO-13623, “Petroleum and natural gas industries — Pipeline transportation systems” (Geneva, Switzerland: International Organization for Standardization).
Hudson Régis Oliveira, “A Proposed Geotechnical Risks Management Plan for Pipeline Integrity,” Proceedings of the ASME 2013 International Pipeline Geotechnical Conference IPG2013-1942.
Geosyntec Consultants Inc., Golder Associates Inc., Center for Reliable Energy Systems (CRES), “Guidelines for the Management of Landslides Hazards for Pipelines” (Washington, DC: Interstate Natural Gas Association of America, Aug. 17, 2020); https://www.ingaa.org/File.aspx?id=38070.
Doug Evans, “Pipeline Route Selection – The Route to Success,” Oil and Gas Technology, International Pipeline & Offshore Contractors Association (IPLOCA); http://www.oilandgastechnology.net/news/pipeline-route-selection-%E2%80%93-route-success.
About Authors:
Girish Babu Nounchi, C.Eng, IGEM-UK, is senior pipeline engineer in Wood and PMT of Saudi Aramco, Al-Khobar, KSA. He has more than 15 years of post-graduate experience with oil and gas pipelines. He holds master’s degree in pipeline engineering from University of Petroleum and Energy Studies and a bachelor’s degree in mechanical engineering from Andhra University, India.
Branko Davidovic, C.Eng, MIMeche, works as a lead pipeline engineer at Wood, Al-Khobar, KSA. He has more than 13 years of post-graduate experience with oil and gas pipelines. He holds MSc degree in mechanical engineering from Josip Juraj Strossmayer University of Osijek and is mechanical engineering faculty in Slavonski Brod, Croatia.
Nychtarikas Dimitrios, M.Sc. C.Eng MEI CEnergy Eng, works as lead pipelines engineer at Wood, Al Khobar, KSA. He has 25 years’ experience in the oil and gas industry, with eight of them with Wood (formerly Amec Foster Wheeler and Foster Wheeler). He holds M.Sc. in electrical engineering – energy sector.
Palash Sanyal is assistant general manager-Pipelines at L&T-OHEC, India. He has more than 15 years of experience with the oil and gas pipelines. He holds a master’s degree in pipeline engineering from University of Petroleum & Energy Studies and a bachelor’s degree in mechanical engineering from WBUT.
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