Showing papers on "Submarine pipeline published in 2010"

Submarine Mass Movements and Their Consequences

Abstract: Submarine mass movements represent major offshore geohazards due to their destructive and tsunami-generation potential. This potential poses a threat to human life as well as to coastal, near shore and offshore engineering structures. Recent examples of catastrophic submarine landslide events that affected human populations (including tsunamis) are numerous; e.g., Nice airport in 1979 (Dan et al. 2007), Finneidfjord in 1996 (e.g., L’Heureux et al., this volume, Steiner et al., this volume), Papua-New Guinea in 1998 (Tappin et al. 2001), Stromboli in 2002 (Chiocci et al. 2008), and the 2006 and 2009 failures in the submarine cable network around Taiwan (Hsu et al. 2008). The Great East Japan Earthquake of March 2011 also generated submarine landslides that may have amplified effects of the devastating tsunami as shown in Fryer et al. (2004). Given that 30% of the World’s population lives within 60 km of the coast, the hazard posed by submarine landslides is expected to grow as global sea level rises. In addition, the deposits resulting from such processes provide-various types of constraints to offshore development (Shipp et al. 2004), and have significant implications for non-renewable energy resource exploration and production (Weimer and Shipp 2004; Beaubouef and Abreu 2010).

The three scales of submarine groundwater flow and discharge across passive continental margins

Abstract: Increased study of submarine groundwater systems in recent years has provided a wealth of new data and techniques, but some ambiguity has been introduced by insufficient distinguishing of the relevant spatial scales of the phenomena studied. Submarine groundwater flow and discharge on passive continental margins can be most productively studied and discussed by distinct consideration of the following three spatial scales: (1) the nearshore scale, spanning approximately 0–10 m offshore and including the unconfined surficial aquifer; (2) the embayment scale, spanning approximately 10 m to as much as 10 km offshore and including the first confined submarine aquifer and its terminus; and (3) the shelf scale, spanning the width and thickness of the aquifers of the entire continental shelf, from the base of the first confined aquifer downward to the basement, and including influences of geothermal convection and glacio-eustatic change in sea level.

Detection of landslides and submarine slumps using broadband seismic networks

Abstract: [1] We detected 52 seismic events associated with landslides and submarine slumps on 8 August 2009 when Typhoon Morakot hit Taiwan. These events were neither felt nor reported because their seismic energy was primarily in the long period band (20-50 s). Most of these events were located in mountain areas where the accumulated rainfall was extremely high, though some were found offshore southern Taiwan. Among all events, the fatal landslide earthquake was located at Hsiaolin Village, where 474 people were buried. Inversion modelling of the seismic waveforms generated by the Hsiaolin landslide shows that the seismic source was represented by single force, consistent with downhill sliding. Some offshore seismic events indicate that submarine slumps probably occurred along submarine canyons and steep slopes. Our study shows that broadband seismic monitoring can be used to issue early warnings for mitigating disasters generated by inland and offshore landslides.

Large Deformation Finite-Element Analysis of Submarine Landslide Interaction with Embedded Pipelines

Abstract: Submarine landslides represent one of the most significant geohazards on the continental slope in respect of the risk they pose to infrastructure such as deep water pipelines. A numerical approach, based on the finite-element method but using remeshing, was established in this paper to simulate large flow deformation of debris from a landslide and to quantify the loads and displacements imposed on pipelines embedded in the seabed. A simple two-dimensional elastic perfectly plastic soil model with plane strain conditions was employed in this analysis. The pipeline was restrained by a set of springs so that the load on the pipeline built up to a stable value, representing the limiting load at which the debris flowed over the pipeline. A parametric study was undertaken by varying the pipeline embedment and the relative strengths of the debris and seabed. The analysis results show that the various combinations of soil strength and embedment depth lead to different debris-pipeline movement patterns and consequ...

Parametric Solutions for Slide Impact on Pipelines

Abstract: Pipelines are frequently subjected to active loading from slide events both on land and in the offshore environment. Whether the pipeline is initially buried or lying close to the surface, and whether it crosses the unstable region or lies in the path of debris originating from further away, the main principles are unchanged. The pipeline will be subjected to active loading over some defined length, related to the width of the slide, and as it deforms will be restrained by transverse and longitudinal resistance in adjacent passive zones. Ultimately the pipeline may come to a stable deformed shape where the continued active loading from the slide is equilibrated by the membrane tension in the pipeline in addition to the passive resistance. This problem has been explored by various writers and these principles are well established. However, to date no attempt has been made to develop a standard set of parametric solutions, which is the purpose of the current paper. Both analytical and numerical solutions of the problem have been developed, initially for slides acting normal to the pipeline but later extended to general conditions with the slide impacting the pipeline at some angle. It is shown that analytical solutions based on certain idealizations maintain their accuracy over a wide parameter range, and the net effect of the slide in terms of stresses induced in the pipe wall and maximum displacement of the pipeline may be captured in appropriate dimensionless groups. Design charts are presented for slide widths of up to 10,000 times the pipeline diameter for a practical range of other parameters such as the ratios of passive normal and frictional resistance to the active loading. Although the solutions are limited by some of the idealizations, they should provide a useful starting point in design, providing a framework for a more detailed numerical analysis for the particular governing conditions.

Mass failures associated with the passage of a large tropical cyclone over the Swatch of No Ground submarine canyon (Bay of Bengal)

Abstract: Acoustic surveys collected six months before and after the passing of a major tropical cyclone over the Swatch of No Ground submarine canyon (Bay of Bengal) revealed the formation of widespread mass failures 30 km offshore of the Ganges-Brahmaputra river delta. Mass sediment flows several kilometers wide with minimal run-out distances ( 1 km wide × 5–60 m thick) developed in areas with preexisting subsurface sediment deformation and evidence for active submarine fluid discharge. In contrast, narrow, steep-walled (7°–10°) gullies present before the storm did not fail, suggesting that the gully walls may be shear hardened by the preferential funneling of gravity flows from the Bengal shelf. Combined, the widespread mass failures and gullies are part of a rapidly accreting (5–50 cm/yr), net-aggradational canyon system that supports multiple mechanisms for sediment transport from the active river mouth to the canyon.

Submarine Mass Movements and Their Consequences : 4th International Symposium

Abstract: 1.- Submarine Mass Movements and Their Consequences.- Submarine Mass Movements: Triggers, Mechanics, and Geotechnical Properties.- Interplay Between Gas Hydrates and Submarine Slope Failure.- Advanced Dynamic Soil Testing - Introducing the New Marum Dynamic Triaxial Testing Device.- Clustering of Geotechnical Properties of Marine Sediments Through Self-Organizing Maps: An Example from the Zakynthos Canyon-Valley System, Greece.- Identification of Shear Zones and Their Causal Mechanisms Using a Combination of Cone Penetration Tests and Seismic Data in the Eastern Niger Delta.- Mass Wasting Dynamics at the Deeper Slope of the Ligurian Margin (Southern France).- Characterization of Micaceous Sand for Investigation of a Subsea Mass Movement.- Estimating Drag Forces on Suspended and Laid-on-Seafloor Pipelines Caused by Clay-Rich Submarine Debris Flow Impact.- Experimental Investigation of Subaqueous Clay-Rich Debris Flows, Turbidity Generation and Sediment Deposition.- The Kinematics of a Debris Avalanche on the Sumatra Margin.- 3D Numerical Modelling of Submerged and Coastal Landslide Propagation.- Peculiar Morphologies of Subaqueous Landslide Deposits and Their Relationship to Flow Dynamics.- Large Landslides on Passive Continental Margins: Processes, Hypotheses and Outstanding Questions.- Origin of Overpressure and Slope Failure in the Ursa Region, Northern Gulf of Mexico.- History of Pore Pressure Build Up and Slope Instability in Mud-Dominated Sediments of Ursa Basin, Gulf of Mexico Continental Slope.- How Does Fluid Inflow Geometry Control Slope Destabilization?.- Geochemical Evidence for Groundwater-Charging of Slope Sediments: The Nice Airport 1979 Landslide and Tsunami Revisited.- Modeling Slope Instability as Shear Rupture Propagation in a Saturated Porous Medium.- Submarine Mass Movements: Case Studies and Hazard Assessment.- Submarine Mass Transport Within Monterey Canyon: Benthic Disturbance Controls on the Distribution of Chemosynthetic Biological Communities.- Multi-direction Flow in a Mass-Transport Deposit, Santos Basin, Offshore Brazil.- Small-Scale Insights into Seismic-Scale Slumps: A Comparison of Slump Features from the Waitemata Basin, New Zealand, and the More Basin, Off-Shore Norway.- The Block Composite Submarine Landslide, Southern New England Slope, U.S.A.: A Morphological Analysis.- Post-Megaslide Slope Stability North of Svalbard, Arctic Ocean.- Geomorphology of the Talisman Slide (Western slope of Hatton Bank, NE Atlantic Ocean).- Investigations on the Peach 4 Debrite, a Late Pleistocene Mass Movement on the Northwest British Continental Margin.- Redistribution of Sediments by Submarine Landslides on the Eastern Nankai Accretionary Prism.- Mass Wasting at the Easternmost Cyprus Arc, Off Syria, Eastern Mediterranean.- Risk Analysis for Hurricane-Wave Induced Submarine Mudslides.- GIS-Based Assessment of Submarine Mudflow Hazard Offshore of the Mississippi Delta, Gulf of Mexico.- Spatial Analysis of Shallow Slope Instability Incorporating an Engineering Geological Ground Model.- Estimating the Empirical Probability of Submarine Landslide Occurrence.- Constraining Geohazards to the Past: Impact Assessment of Submarine Mass Movements on Seabed Developments.- Evaluating Gas-Generated Pore Pressure with Seismic Reflection Data in a Landslide-Prone Area: An Example from Finneidfjord, Norway.- Historic and Paleo-Submarine Landslide Deposits Imaged Beneath Port Valdez, Alaska: Implications for Tsunami Generation in a Glacial Fiord.- Multibeam Bathymetry Investigations of Mass Movements in Lake Le Bourget (NW Alps, France) Using a Portable Platform.- Morphodynamic and Slope Instability Observations at Wabush Lake, Labrador.- Climate-Induced Turbidity Current Activity in NW-African Canyon Systems.- Submarine Mass Movements in Margin Construction and Economic Significance.- Investigating the Timing, Processes and Deposits of One of the World's Largest Submarine Gravity Flows: The 'Bed 5 Event' Off Northwest Africa.- MTCs of the Brazos-Trinity Slope System Thoughts on the Sequence Stratigraphy of MTCs and Their Possible Roles in Shaping Hydrocarbon Traps.- Southeast Australia: A Cenozoic Continental Margin Dominated by Mass Transport.- A Database on Submarine Landslides of the Mediterranean Sea.- Submarine Landslides Along the Algerian Margin: A Review of Their Occurrence and Potential Link with Tectonic Structures.- Mass-Transport Deposits on the Algerian Margin (Algiers Area): Morphology, Lithology and Sedimentary Processes.- Detailed Analysis of a Submarine Landslide (SAR-27) in the Deep Basin Offshore Algiers (Western Mediterranean).- 3D Seismic Interpretation of Mass Transport Deposits: Implications for Basin Analysis and Geohazard Evaluation.- Slope Instability on the French Guiana Transform Margin from Swath-Bathymetry and 3.5 kHz Echograms.- Megaslides in the Foz do Amazonas Basin, Brazilian Equatorial Margin.- Detached and Shelf-Attached Mass Transport Complexes on the Magdalena Deepwater Fan.- Character, Distribution and Timing of Latest Quaternary Mass-Transport Deposits in Texas-Louisiana Intraslope Basins Based on High-Resolution (3.5 kHz) Seismic Facies and Piston Cores.- Upper Cretaceous Mass Transport Systems Above the Wyandot Formation Chalk, Offshore Nova Scotia.- The Significance of Mass-Transport Deposits for the Evolution of a Proglacial Continental Slope.- Submarine Mass Movements and Tsunamis.- Middle to Late Miocene Slope Failure and the Generation of a Regional Unconformity Beneath the Western Scotian Slope, Eastern Canada.- Mass Transport Deposits on the Southwestern Newfoundland Slope.- Mass Transport Events and Their Tsunami Hazard.- Hydrodynamic Modeling of Tsunamis Generated by Submarine Landslides: Generation, Propagation, and Shoreline Impact.- Calculations of Tsunamis from Submarine Landslides.- Experiments on Tsunamis Generated by 3D Granular Landslides.- Distal Turbidites and Tsunamigenic Landslides of Stromboli Volcano (Aeolian Islands, Italy).- Tsunamigenic Risks Associated with Mass Transport Complexes in Offshore Trinidad and Venezuela.- Distribution and Tsunamigenic Potential of Submarine Landslides in the Gulf of Mexico.- A Study of the Tsunami Effects of Two Landslides in the St. Lawrence Estuary.- The Pliocene Shelburne Mass-Movement and Consequent Tsunami, Western Scotian Slope.

Development of an autonomous in‐pipe robot for offshore pipeline maintenance

Abstract: – The purpose of this paper is to develop a novel autonomous in‐pipe robot to perform the preventive point reparation for long‐distance offshore oil pipelines., – The autonomous in‐pipe robot performs online ultrasonic inspection for pipe wall thickness, and the original inspection data are stored in large capacity hard disk. Through the offline data analysis by the data analysts and the software tool, the pipeline health status is known. If server defects lie there, the in‐pipe robot is introduced into the pipeline once more to indicate the defect's location to the maintenance ship., – The laboratory tests and the field tests prove the feasibility and validity of the developed autonomous in‐pipe robot. Furthermore, the application of intelligent control techniques ensures the mission completion by the autonomous in‐pipe robot, which worked in the awful pipeline environment., – The developed autonomous in‐pipe robot helps eliminate lost production costs and pipeline downtime caused by leakages and guarantees the safe run of offshore oil pipelines., – For the application of the autonomous in‐pipe robot, there are no special requirements for maintained pipelines themselves, so it is applicable to the point reparation for most long‐distance welded offshore pipelines.

Erosion and accretion processes in a muddy dissipative coast, the Chao Phraya River delta, Thailand.

Abstract: Seasonal variation in seabed elevation in the muddy intertidal zone of the Chao Phraya River delta, an area of serious coastal erosion for 40 years, was assessed using information on waves and tides predicted by numerical simulations. The study area is under the influence of the Southeast Asian monsoon climate and lies in the innermost part of a sheltered gulf, across which a low-gradient slope has developed. Observations, aimed at evaluating the effectiveness of a prototype breakwater on mitigating coastal erosion, indicated that the seasonal variation in the seabed elevation, typically about 30 cm, was caused primarily by seasonal changes in wave direction and height. The breakwater seems to have contributed to a net rise in the seabed level at sites behind the structure. Seabed erosion was most apparent during the northeast monsoon, when waves are weak. Erosion under this low wave energy state was attributed to the combined effect of wave breaking and the low tidal level. A difference in the observed seabed accretion rate between the transitional intermonsoon period and the succeeding southwest monsoon period was attributed to the direction of the wave energy flux; offshore sediments seem to have been supplied efficiently to the study area by waves during the transitional period. Another potential cause of seabed erosion and accretion during the wet southwest monsoon season was the discharge of water and sediments from local canals associated with intense tropical rainfall; this discharge seems to be linked to land use in the coastal area. The results of this study show the importance of monitoring across-shore sediment transport for better understanding of coastal erosion processes. Copyright © 2010 John Wiley & Sons, Ltd.

Three‐dimensional structure of the submarine flanks of La Réunion inferred from geophysical data

Abstract: [1] La Reunion (Indian Ocean) constitutes a huge volcanic oceanic system of which most of the volume is submerged. We present a study of its submarine part based on the interpretation of magnetic and gravity data compiled from old and recent surveys. A model of the submarine internal structure is derived from 3-D and 2-D models using constraints from previous geological and geophysical studies. Two large-scale, previously unknown, buried volcanic construction zones are discovered in continuation of the island's construction. To the east, the Alizes submarine zone is interpreted as the remnants of Les Alizes volcano eastward flank whose center is marked by a large hypovolcanic intrusion complex. To the southwest, the Etang Sale submarine zone is interpreted as an extension of Piton des Neiges, probably fed by a volcanic rift zone over a large extent. They were predominantly built during the Matuyama period and thus probably belong to early volcanism. A correlation exists between their top and seismic horizons recognized in previous studies and interpreted as the base of the volcanic edifice. Their morphology suggested a lithospheric bulging beneath La Reunion, not required to explain our data, since the seismic interfaces match the top of our volcanic constructions. The coastal shelf coincides with a negative Bouguer anomaly belt, often associated with magnetic anomalies, suggesting a shelf built by hyaloclastites. A detailed analysis of the offshore continuation of La Montagne Massif to the north confirms this hypothesis. The gravity analysis confirms that the bathymetric bulges, forming the northern, eastern, southern, and western submarine flanks, are predominantly built by debris avalanche deposits at the surface.

Flow-Pipe-Seepage Coupling Analysis oF Spanning Initiation of a Partially-Embedded Pipeline

Abstract: The initiation of pipeline spanning involves the coupling between the flow over the pipeline and the seepage-flow in the soil underneath the pipeline. The pipeline spanning initiation is experimentally observed and discussed in this article. It is qualitatively indicated that the pressure-drop induced soil seepage failure is the predominant cause for pipeline spanning initiation. A flow-pipe-seepage sequential coupling Finite Element Method (FEM) model is proposed to simulate the coupling between the water flow-field and the soil seepage-field. A critical hydraulic gradient is obtained for oblique seepage failure of the sand in the direction tangent to the pipe. Parametric study is performed to investigate the effects of inflow velocity, pipe embedment on the pressure-drop, and the effects of soil internal friction angle and pipe embedment-to-diameter ratio on the critical flow velocity for pipeline spanning initiation. It is indicated that the dimensionless critical flow velocity changes approximately linearly with the soil internal friction angle for the submarine pipeline partially-embedded in a sandy seabed.

Groundwater conditions along the seawater/freshwater interface on a volcanic island and a depositional area in Japan

Abstract: Fresh groundwater comes in contact with seawater at the downstream end of its flow system. Most previous work has discussed the shape of the seawater/freshwater interface on the basis of Ghyben-Herzberg's law. The groundwater, however, pushes the seawater farther offshore side than predicted by the law, giving rise to freshwater flows even below the bottom of the sea. A previous study found that the distribution of submarine groundwater discharge and the point of the seawater/freshwater interface on the marine floor are closely related. The cross-sectional shape of the interface onshore is clarified by using electrical tomography and observation of groundwater and soil samples taken from observation wells located in the coastal area (by a volcanic island and associated deposits). In both fields, diving was carried out to find the submarine groundwater discharge on the sea-floor and to take water samples. From the analysis of the water discharged on the marine floor and/or electric conductivity measurements in the marine sands, it is shown the freshwater flows (discharges) along the interface, even in the submarine deposits. The understanding of groundwater flows at the downstream end of the groundwater flow system (from mountainous to marine) will facilitate the development of water resources and the evaluation of environments.

Investigating the Timing, Processes and Deposits of One of the World's Largest Submarine Gravity Flows: The ‘Bed 5 Event’ Off Northwest Africa

Abstract: An extensive dataset of shallow sediment cores is used here to describe one of the World's most voluminous and extensive submarine gravity flows The Bed 5 event, dated at ~60 ka, originated on the upper slope offshore Atlantic Morocco, in the vicinity of Agadir Canyon The volume of initial failure was ~130 km3 of sediment, and the failure appeared to rapidly disintegrate into a highly mobile turbidity current Widespread substrate erosion beneath the flow occurred up to 550 km from the interpreted source, and is estimated to have added a further 30 km3 of sediment The flow spread upon exiting Agadir Canyon, with deposition occurring across both the Agadir Basin and Seine Abyssal Plain Evidence for flow transformations and linked turbidite-debrite development can be found in both basins, and there are also indications for sediment bypass and fluid mud behaviour A portion of the flow subsequently spilled out of the western Agadir Basin, and passed through the Madeira Channels prior to deposition on the enclosed Madeira Abyssal Plain at 5,400 m water depth The total run-out distance along the flow pathway is about 2,000 km, with only about half of the pathway confined to canyon or channel environments Our results show that large-volume submarine landslides can rapidly disintegrate into far-traveling fluid turbidity currents, and that deposi-tional processes within such flows may be complex and spatially variable

The Forecasting Residual Life of Corroding Pipeline based on Semi-Probabilistic Method

Abstract: In general, the prediction of pipeline residual life can effectively assist pipeline operators to evaluate future safe operating strategies including re-inspection and appropriate maintenance schedule. As a result it can minimize the possibility of pipeline failures until it reaches its designed lifetime. A semi-probabilistic methodology for predicting the remaining strength of submarine pipelines subjected to internal corrosion based on Recommended Practice RP-F101 by Det Norske Veritas (DNV) is described in this paper. It is used to estimate the maximum allowable operating pressure of the corroding pipelines based on series of pigging data, which represents corrosion pit location and dimension. The introduction of partial safety factors in the DNV code to minimise the effect of uncertainties due to the defect sizing has improved the reliability of pipeline assessment methodology. Nevertheless, the code is still regarded as a fully deterministic approach due to its incapability of predicting the remaining life of corroded pipeline. Thus, we have added prediction capabilities to the capacity equation by introducing a standard deviation model of future defect depth. By doing so, the variation of safety factors of the capacity equation can be fully manipulated in which prediction of future pipeline residual life becomes feasible. The paper demonstrates calculation and prediction of pipeline residual life subjects to internal corrosion. The results shows the standard deviation of corrosion parameter affected the value of partial safety factor as corrosion progressing, hence amplify the conservatism of time to failure.

Towards a Computational Tool For the Synthesis And Optimization of Submarine Pipeline Routes

Abstract: This work describes the steps that are currently being taken for the development of a computational tool for the synthesis and optimization of submarine pipeline routes. Such tool, based on Evolutionary Algorithms, will incorporate criteria related to several aspects of the design of pipelines, including total pipeline length; geophysical and geotechnical data from bathymetry and sonography, including definition of obstacles and regions to be avoided; number, length and location of free spans; analysis and verification of on-bottom stability under hydrostatic and hydrodynamic loadings; and other aspects related to the structural behavior of the pipe. Here, special attention is dedicated to the geometrical representation of a route, and to the terms of the objective (fitness) function associated to a preliminary, global step of the optimization process.

An inventory and evaluation of unmanned aerial systems for offshore surveys of marine mammals

Abstract: A literature review, internet searches and communications with personnel working with unmanned aerial systems (UAS) were used to identify the capabilities of UAS throughout the world. We assessed their ability to replace manned aerial surveys for marine mammals, sea turtles and seabirds and to monitor, in real time, sea ice and other physical features that might influence marine mammal distribution. The vast majority of the systems identified were either too expensive or their capabilities did not meet minimum standards necessary to perform the tasks required of them in real time. Eight systems were identified that might be able to perform some of the desired tasks. Several other systems had similar capabilities but had not been tested or would require upgrades. Installation of high-definition (HD) video and better stabilisation systems would improve UAS performance. It is recommended that development of HD video with real-time data transmission and improved stabilisation systems for UAS be pursued and that side-by-side comparisons of a few of the best systems be conducted.

A parallel three-dimensional scour model to predict flow and scour below a submarine pipeline

Abstract: A three-dimensional Lattice Boltzmann flow and scour model is developed to simulate time-dependent scour below a submarine pipeline. The proposed model presented in this paper is able to predict streamwise and spanwise propagations of scour with respect to lattice unit of time. It is evident from this study that the existence of a spiral vortex in the proximity of the span shoulder is quite noteworthy. It is revealed that the critical regime of the 2-D scour process is found to be up to one pipe diameter away in both directions from the middle of the unsupported length of pipelines. The equilibrium maximum scour depth and the shape of streamwise equilibrium scour hole compare well with the available experimental data. The speed of propagation of scour along the pipeline length maintains an almost constant rate, which is consistent with the experimental observations found in literature. In addition, it is seen that the scour slope at the shoulder region remains fairly constant throughout the whole scour process.

Modelling of submarine slides in the geotechnical centrifgue

Abstract: The depletion of near shore hydrocarbon resources has led to a move to exploration and production in deep and ultra-deep waters. This shift into deeper waters requires increased reliance on sub-sea installations and pipelines that can extend to more than 500 km from shore, often across areas of changing seabed morphology and continental shelves. The viability of these developments is increasingly dependent on the security of the installations and tie-backs to shore, which are susceptible to geohazards such as submarine slides. The Centre for Offshore Foundation Systems (COFS) has initiated research to investigate the impact of submarine slides on offshore pipelines. As part of this project, a facility has been developed to model submarine slides in the geotechnical drum centrifuge at the University of Western Australia. This facility uses the long narrow channel of the drum centrifuge to model the run-out of submarine slides that are triggered from an intact block of clay, along a model seabed. This paper describes the development of the apparatus to trigger the slides in the drum centrifuge and presents some results from the first tests conducted in the facility.

Capturing carbon dioxide: the feasibility of re-using existing pipeline infrastructure to transport anthropogenic CO2

Abstract: Climate change has been attributed to green house gases, with carbon dioxide (CO2) being the main contributor. Sixty to seventy percent of carbon dioxide emissions originate from fossil fuel power plants. Power companies in the UK, along with oil and gas field operators, are proposing to capture this anthropogenic CO2 and either store it in depleted reservoirs or saline aquifers (carbon capture and storage, CCS), or use it for 'Enhanced Oil Recovery' (EOR) in depleting oil and gas fields. This would involve extensive onshore and offshore pipeline systems. The decline of oil and gas production of reservoirs beyond economic feasibility will require the decommissioning onshore and offshore facilities post-production. This creates a possible opportunity for using existing pipeline infrastructure. Conversions of pipelines from natural gas service to CO2 service for EOR have been done in the United States. However, the differing sources of CO2 and the differing requirements for EOR and CCS play a significant part in allowing the re-use of existing infrastructure. The effect of compositions, the phase of transportation, the original pipeline specifications, and also the pipeline route require major studies prior to allowing re-use. This paper will first review the requirements for specifying the purity of the CO2 for CCS and to highlight the implications that the presence of impurities and the current water specifications for pipelines has on the phase diagram and the associated physical properties of the CO2 stream. A 'best' and 'worst' case impurity specification will be identified. Then an analysis on the impact and subsequent validation, of equations of state based on available experimental data on the phase modelling of anthropogenic CO2 is presented. A case study involving an existing 300km gas pipeline in the National Transmission System (NTS) in the UK is then modelled, to demonstrate the feasibility of using this pipeline to transport anthropogenic CO2. The various issues involved for the selected 'best' and 'worst' case specification are also covered. This is then followed by an investigation of the options for transport in the 'gas' phase and 'supercritical' phases, and also identifying the limitations on re-using pipeline infrastructure for CCS.

A Model to Estimate the Failure Rates of Offshore Pipelines

Abstract: Pipelines are subjected to several threats which can cause failure of the line, such as external impact, mechanical defects, corrosion and natural hazards. In particular, offshore operations present a unique set of environmental conditions and adverse exposure not observed in a land environment. For example, offshore pipelines located near harbor areas and in major shipping lanes are likely to be exposed to the risk of damage from anchor and dropped object impact. Such damage may result in potential risk to people and the environment, and significant repair costs. Quantitative Risk Assessment (QRA) is a method which is often used in the oil and gas industry to predict the level of risk. In QRA calculations the frequency of an incident is often assessed by a generic failure frequency approach. Generic failure frequencies derived from local incident databases are largely used in pipeline risk assessments. As a result, risk assessments for offshore pipelines may not reflect accurately operational experience for a specific pipeline or region of operation. In addition, a better understanding of the causes and characteristics of pipeline failure should provide important information to improve inspection and maintenance activity for existing pipelines and to aid in selection of design criteria for new pipelines. This paper presents an analysis of the failure data from various pipelines databases to see if there is a common trend regarding failure rates, and failure-rate dependence on pipeline parameters. A breakdown of the causes of failure has been carried out. The effect on failure frequency of factors such as pipeline age, location, diameter, wall thickness, steel grade, burial depth, and fluid transported have been investigated and are discussed. The objective of this paper is to provide a guideline for the determination of failure frequency for offshore pipelines and to describe a new model developed for use within BP for this purpose. This model uses historical databases and predictive methods to develop failure frequencies as a function of a range of influencing parameters.Copyright © 2010 by ASME

Centrifuge modelling of submarine landslide flows

Abstract: Landslides occur both onshore and offshore, however little attention has been given to offshore landslides (submarine landslides). The unique characteristics of submarine landslides include large mass movements and long travel distances at very gentle slopes. Submarine landslides have significant impacts and consequences on offshore and coastal facilities. This paper presents data from a series of centrifuge tests simulating submarine landslide flows on a very gentle slope. Experiments were conducted at different gravity levels to understand the scaling laws involved in simulating submarine landslide flows through centrifuge modelling. The slope was instrumented with miniature sensors for measurements of pore pressure beneath the flow. A series of digital cameras were used to capture the flow in flight. The results provide a better understanding of the scaling laws that needs to be adopted for centrifuge experiments involving submarine landslide flows and gives an insight into the flow mechanisms. © 2010 Taylor & Francis Group, London.

Strain Demand Estimation for Pipelines in Challenging Arctic and Seismically Active Regions

Abstract: The need to use strain-based design is growing due to potential pipeline projects in environments that include permafrost, offshore ice hazards, active seismic areas and high temperature/high pressure operations. Proper design and construction of such pipelines poses numerous special challenges and requires consideration of some important processes that govern the behavior of soils. ExxonMobil has been conducting research to improve understanding of geotechnical mechanisms that result in large plastic strains in the pipelines, and to develop pipeline strain demand prediction methodologies in harsh arctic and seismically active regions. This paper discusses key challenges in strain demand estimates for Arctic onshore and offshore pipelines and is aimed at promoting industry discussion of strain demand prediction methodologies. The paper highlights ExxonMobil’s efforts in developing predictive technologies for strain demand estimation that forms the basis for the design, testing, and model development in strain-based pipeline applications.Copyright © 2010 by ASME

Calculation of maximum allowable free span length and safety assessment of the DF1-1 submarine pipeline

Abstract: The DF1-1 submarine pipeline was investigated using a dual-frequency side-scan sonar and a swath sounder system. More than a hundred scour pits under the pipeline were found, most of which have caused the span of the pipeline to increase and threatened its safety. The maximum allowable free span length (MAFSL) of the pipeline was determined through the limitations regarding maximum allowable stress under static or quasi-static loads and the onset of Vortex Induced Vibrations (VIV) under different hydrodynamic actions. The results show that the MAFSL under static conditions is 56 m. However, the MAFSLs are 30 m and 20 m under ordinary weather conditions and hurricane-induced currents for the 100-year return period, respectively, to avoid VIV as calculated by using the highest safety class factor. It is suggested that spanning pipelines longer than 20 m should be supported. Additionally, eight successive spans which may also threaten the pipeline were proposed. The most hazardous scour pits are along the pipeline section from KP42 to KP51.

Study of submarine pipeline corrosion based on ultrasonic detection and wavelet analysis

Abstract: Pipeline inspection is an important means of Oil and Gas Pipeline defect detection; it plays an important role in the protection of the safe operation of pipelines. Ultrasonic detection technology becomes the main pipe online detection method, because of the advantages of its fast speed, reliability, economy and doesn't require strip layer penstock. In ultrasonic flaw detection process ultrasonic signal usually is a center frequency modulation of broadband pulse signal, this is a time-frequency limited amount of non-stationary signal, wavelet analysis is a new mathematical method and data processing tool to analyze non-stable signals. This article on seabed pipeline corrosion conditions detection and the first part of the difficulty of collecting data, using the combination of hardware and software to solute the online ultrasonic thickness data and location data synchronization acquisition problems in this paper, Secondly, in LABVIEW software by fully utilizing Wavelet analysis method for multiple reflection on ultrasonic pulse-echo power spectrum for extraction, and through experiment illustrates that this method is accurate and reliable in the extraction of ultrasound on the peak information, it also laid the foundation of pipeline defect identification and location.