RISK ASSESSMENT OF HYDROCARBON PIPELINES FACING NATURAL HAZARDS

Transcription

1 UN Environment / UN OCHA Joint Unit Prepare. Respond. Protect OECD Working Group on Chemical Accidents Federal Ministry for the Environment, Nature Conservation and Nuclear Safety Ministry for Rural Development, the Environment and Agriculture of Brandenburg German Environment Agency UN/ OECD Workshop on Natech Risk Management (Natural-hazard triggered technological accidents) RISK ASSESSMENT OF HYDROCARBON PIPELINES FACING NATURAL HAZARDS By José Vicente Amórtegui Gil, CE Professor of the Colombian School of Engineering 5 to 7 September 2018, Potsdam, Germany

2 Risky situation.

3 Risk calculation by geotechnical factors: R = Prupture x Consequence In Colombia There is an index of pipeline rupture/km/year, for the Andean (mountaineous) area, or ruptures/km/year, for the whole country. COSTS ASSOCIATED TO A SINGULAR EMERGENCY OF A PIPELINE (Tipical event) Loss of product (10kB), USD $ 60/barrel...USD$ Repairs Decontamination Lost profit, 4 days, 100 KBD (USD$10/barrel) Fines (by environmental institutions) Claims (by affected people) TOTAL.. USD$ Risk = USD$ 4725 /km/year IN GAS PIPELINES THE COST CAN BE: USD$ Risk = USD$ 1875 /km/year

4 Consequences

5 (RAM) The RAM matrix in situations of high consequence yields an unacceptable risk result, even in a threat-free condition. This inhibits the performance of actions to mitigate the risk.

6 DEFINITION OF RISK (Traditional and Proposal). Risk = f(rupture probability, Consequence) Probability of pipeline rupture = f (Exposition, Mitigation, Resistance). Exposition: Probability that the threatening process affects the pipeline. Mitigation: Actions to control the threat. Resistance: Ability of system to resist threats. Where R = Pa x V x C R is the risk to which the system is exposed, which can be represented with value units ($), Pa is the probability of occurrence of a hazard during the time of exposure of the system to that hazard, V is the vulnerability of the system to the hazard; it can be expressed as the fraction of damage expected and, Consequence: Cost of damages and repair. C is the consequence that can be expressed in the value of damage or its repair ($). Hazard: Probability of occurrence of a process with determined intensity or severity level, within a given period of time and in an specific area. p = 1 ( 1 1/T) t T = 1/P (a) Vulnerability of a pipeline = f (Resistance, Deformability, State of stress, Geometry, Age, Conditions of installation and operation, Mechanical condition).

7 Geological and metheorological processes that can be considered hazards Landslides and earth flows. Sinking and subsidence. Erosion and scour. Ground expansivity and collapsibility. Weathering of soils and rocks. External geodynamics Earthquakes and tsunamis. Vulcanism. Diapirism. Internal geodynamics Torrential rains and high precipitations. Floods and Flooding. Hurricanes. Tornados Meteorological

8 The tectonic cycle generates the plate formation and destruction, the formation of mountains, vulcanism, induces earthquakes and tsunamis, changes the position of polar glaciers; stimulates the rock and hydrological cycles, this, with the help of the atmosphere s currents and the shape of the mountains, participates in the rock and biogeochemical cycles.

9 Colombian tectonic model There are strong faults that divide the regions of the country: Eastern plains, mountain ranges and valleys subjected to flooding. Due to the closeness of the subduction zone there are volcanic ranges and high tendency to earthquakes. The mountain ranges suffer the uplifting process.

10 RISK ASSESSMENT: Vulnerability. Forces on a pipeline under ground movement. Flexion Traction Traction Torsion Traction Compression Compression

11 RISK EVALUATION: Procedure to evaluate the Threat by climate and external forces. Natural hazards. For the threat coming from climate and external forces, including terrain movements, the incidence of natural processes on a potential rupture, the mitigation or reinforcement of the terrain, ground that has been put into practice, the probability of occurrence of such natural processes and the capacity of the pipeline to withstand the effects of natural processes, must be assessed. Many of the natural processes, in themselves, do not affect the integrity of the pipelines, however, they can trigger other processes that involve ground movements, which eventually impose thrusts on the pipelines. From the geotechnical viewpoint, there is a culture of evaluation of the threat, especially of landslides, where the analyses involve the resistance and variability of the parameters, the detonating factors or processes (rains, earthquakes) with their probability of occurrence, the effect of the reinforcement works and the conditional probability that the threatening process is generated during a period of time.. Instability terrain = f (Resistance, disposition, stress state, triggers, reinforcement). Ground resistance = f (lithology, moisture, weathering).. Weathering = f (lithology, weather, land use).. Stress state = f (density, tectonics, hydrostatic pressure, seismic stresses).. Triggers = (rains, action of water currents, earthquakes, human activities). With analysis it is possible to determine the probability of occurrence of an instability process.

12 RISK ASSESSMENT: Susceptibility to landslides. RISK ASSESSMENT PROCEDURE In order to facilitate the analyses, it is recommended to carry them out on the sections of high and very high susceptibility (for the Colombian pipeline network it is <20%): 1.Determine the existence and location of the threatening processes, as well as their causes and triggers, and calculate the probability that they occur within the area of influence of the pipelines (Pa). 2. Evaluate the characteristics of the pipeline and its relationship to the threatening process, to determine the potential for damage that may occur (V). Susceptibility (%) Very Low or Low 51.2 Moderate 29.2 High Determine the cost of the consequences of the loss of pipeline containment, on the environment, the neighbors, the regional infrastructure, the Authorities and the transportation system (C). R = Pa x V x C Very high 1.3 Fuente: IDEAM- Ecopetrol S.A

13 HAZARD CONTROL: RISK CONTROL Acknowledge the hazards to which the duct and it s evolution can be exposed to. Avoid the more hazardous sites, by means of the an appropiate route selection. Minimize the affectation of the ground during construction. Reinforce the ground. Evaluate the evolution of the processes considered as threat VULNERABILITY CONTROL: Evaluate the pipe features, regarding the hazards to which it might be exposed to. Monitor the pipe behavior. Upkeep of the system to adequate it to the hazard changes. Temporarily isolate the duct. CONSEQUENCE CONTROL: Reduce the exposed elements in the pipeline influence area: Conduction trace, government regulations and real estate administration. Pipeline sectioning with valves; and contingency plan reinforcement.

14 Pipeline Route: Through the top of the hills to diminish the land volume in the right-of-way conformation. On the most stable grounds. Water bodies crossing through the most stable place and at safe depth and distance from the stream course.

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16 Above-ground Pipeline Variability during life period

17 Buried Pipeline Variability during life period

18 TERRAIN REINFORCEMENT: Drainage elements: current breakers, channels, filters and horizontal drains. Erosion resistant cover, preferably with vegetation. Retaining structures.

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20 MONITORING PROPOSAL Specialized geotechnical diagnosis (every 5 years). Field trips through the pipeline paths (every 6 months). Inspection from inside the pipeline (every 5 years). Environmental information gathering: weather, meteorology, river floods, earthquakes, hurricanes, volcanoes (permanently). Air reconnaisance trips (each 6 months). Critical sites inspection (monthly). Determine the thresholds that trigger hazards. Define decision algorithms to take actions to prevent rupture of the pipeline.

21 UPKEEP: Repairing of damaged frames. Increasing of vegetation cover. Release the pipeline to correct distortions. Drainage improvement.

22 REFERENCES [1] Amórtegui, José V Natural Hazard in Hydrocarbon Transportation Lines, Geotechnical Special Publication No ASCE GeoInstitute, Hunan, China. [2] Amórtegui, José V Pipeline Vulnerability to Natural Hazards, Proceedings of the ASME 2015 International Pipeline Geotechnical Conference IPG2015, Bogotá, Colombia. [3] Amórtegui, José V Risk Assessment of Hidrocarbon Pipelines Facing Natural Hazards, Proceedings of the ASME 2017 International Pipeline Geotechnical Conference IPG2017, Lima, Perú. [4] Aristizábal C. Jaime H. and Chaves, Julian, Panorama of the Strategy for Managing the Risk Created by the Weather-Related and Outside Force Threat in VIT- ECOPETROL, Proceedings of the ASME 2015 International Pipeline Geotechnical Conference IPG2015, Bogotá, Colombia. [5] ASME B31.8S Managing System Integrity of Gas Pipelines. [6] Mora, R. G., Hopkins, P., Cote, E. I., Shie, T., 2016, Pipeline Integrity Management Systems: A Practical Approach, ASME Press, New York, USA. [7] Mora, R. G., 2018, Cost-Effective Risk Reduction Approach (CERRA): Pipeline Geohazard Case Study, ASME Geohazard Book, Text in edition.

23 Thank you very much!