Showing papers on "Submarine pipeline published in 2019"
TL;DR: A fuzzy-based risk model is developed for prioritizing primary and residual risk and is applied to a case study for clearing and grading process of a natural gas pipeline project.
Abstract: A natural gas pipeline project is a broad construction system consisting of both offshore and onshore section, which aims to supply the natural gas to one country to another. In such these projects...
69 citations
TL;DR: In this paper, the authors investigated the compressive and flexural behavior of a submarine composite pipeline under internal content pressure and external hydrostatic pressure through finite element analysis (FEA), where non-linear material properties of stainless steel and composite actions between constituent parts were considered.
62 citations
TL;DR: The data provide more continuous constraints on offshore groundwater than previous models and present evidence for a connection between the modern onshore hydrologic system and offshore aquifers, and identify clinoforms as a previously unknown structural control on the lateral extent of low-salinity groundwater.
Abstract: Low-salinity submarine groundwater contained within continental shelves is a global phenomenon. Mechanisms for emplacing offshore groundwater include glacial processes that drove water into exposed continental shelves during sea-level low stands and active connections to onshore hydrologic systems. While low-salinity groundwater is thought to be abundant, its distribution and volume worldwide is poorly understood due to the limited number of observations. Here we image laterally continuous aquifers extending 90 km offshore New Jersey and Martha’s Vineyard, Massachusetts, on the U.S. Atlantic margin using new shallow water electromagnetic geophysical methods. Our data provide more continuous constraints on offshore groundwater than previous models and present evidence for a connection between the modern onshore hydrologic system and offshore aquifers. We identify clinoforms as a previously unknown structural control on the lateral extent of low-salinity groundwater and potentially a control on where low-salinity water rises into the seafloor. Our data suggest a continuous submarine aquifer system spans at least 350 km of the U.S. Atlantic coast and contains about 2800 km3 of low-salinity groundwater. Our findings can be used to improve models of past glacial, eustatic, tectonic, and geomorphic processes on continental shelves and provide insight into shelf geochemistry, biogeochemical cycles, and the deep biosphere.
50 citations
TL;DR: In this article, a series of comprehensive laboratory experiments are carried out in a wave flume to investigate the wave-induced pore pressures around a partially embedded pipeline in a trench layer.
39 citations
TL;DR: In this paper, a 3D integrated model for the wave-induced seabed residual response around a mono-pile is developed by considering the inertial terms of pore fluid and soil skeleton.
38 citations
TL;DR: This article used sediment trap samples, velocity measurements, and seafloor cores to document how sand is transported through a submarine canyon, and how the transported sediment is represented in seabed deposits.
Abstract: Submarine canyons are conduits for episodic and powerful sediment density flows (commonly called turbidity currents) that move globally significant amounts of terrestrial sediment and organic carbon into the deep sea, forming some of the largest sedimentary deposits on Earth. The only record available for most turbidity currents is the deposit they leave behind. Therefore, to understand turbidity current processes, we need to determine the degree to which these flows are represented by their deposits. However, linking flows and deposits is a major long-standing scientific challenge. There are few detailed measurements from submarine turbidity currents in action, and even fewer direct measurements that can be compared to resulting seabed deposits. Recently, an extensive array of moorings along Monterey Canyon, offshore California, took measurements and samples during sediment density flow events, providing the most comprehensive dataset to date of turbidity current flows and their deposits. Here, we use sediment trap samples, velocity measurements, and seafloor cores to document how sand is transported through a submarine canyon, and how the transported sediment is represented in seafloor deposits. Sediment trap samples from events contain primarily fine to medium-grained sand with sharp bases, normal grading, and muddy tops. Sediment captured from the water column during the flow shows normal grading, which is broadly consistent with the initial peak and waning of flow velocities measured at a single height within the flow, and may be enhanced by collapsing flows. Flow events contain coarser sand concentrated toward the seafloor and larger grain sizes on the seafloor or in the dense near-bed layer, possibly representative of stratified flows. Although flow velocity varies, sand grain sizes in sediment traps are similar over distances of 50 km down-canyon, suggesting that grain size is an unfaithful record of down-canyon changes in maximum flow speeds. Sand transported within flow events and sampled in sediment traps is similar to sand sampled from the seafloor shortly after the events, but traps do not contain pebbles and gravel common in seabed deposits. Seabed deposits thus appear to faithfully record the sand component that is transported in the water column during sub-annual turbidity currents.
34 citations
TL;DR: In this article, the authors applied the CryoGRID2 heat diffusion model and coupled it to a salt diffusion model to better quantify nearshore subsea permafrost thawing.
Abstract: Thawing of subsea permafrost can impact offshore infrastructure, affect coastal erosion, and release permafrost organic matter. Thawing is usually modeled as the result of heat transfer, although salt diffusion may play an important role in marine settings. To better quantify nearshore subsea permafrost thawing, we applied the CryoGRID2 heat diffusion model and coupled it to a salt diffusion model. We simulated coastline retreat and subsea permafrost evolution as it develops through successive stages of a thawing sequence at the Bykovsky Peninsula, Siberia. Sensitivity analyses for seawater salinity were performed to compare the results for the Bykovsky Peninsula with those of typical Arctic seawater. For the Bykovsky Peninsula, the modeled ice-bearing permafrost table (IBPT) for ice-rich sand and an erosion rate of 0.25 m/year was 16.7 m below the seabed 350 m offshore. The model outputs were compared to the IBPT depth estimated from coastline retreat and electrical resistivity surveys perpendicular to and crossing the shoreline of the Bykovsky Peninsula. The interpreted geoelectric data suggest that the IBPT dipped to 15-20 m below the seabed at 350 m offshore. Both results suggest that cold saline water forms beneath grounded ice and floating sea ice in shallow water, causing cryotic benthic temperatures. The freezing point depression produced by salt diffusion can delay or prevent ice formation in the sediment and enhance the IBPT degradation rate. Therefore, salt diffusion may facilitate the release of greenhouse gasses to the atmosphere and considerably affect the design of offshore and coastal infrastructure in subsea permafrost areas.
32 citations
TL;DR: In this article, the authors proposed a pipeline with honeycomb holes to reduce the impact of landslides, sand waves and bottom currents on the pipeline to protect the operational safety, and demonstrated that the higher is the Reynolds number, the larger the resistance reduction effect.
31 citations
TL;DR: In this article, the impact forces exerted by a submarine landslide on laid-on or suspended pipelines at various impact angles were simulated using the computational fluid dynamics (CFD) approach, and an equation for calculating the acting forces on a pipeline along the flow direction of a submarine landslides that comprehensively accounts for the effects of θ and H was proposed.
28 citations
TL;DR: A multi-sensor surveying system was used, which integrates a sub-bottom profiler (SBP) and the Shipborne Over- and Under-Water Integrated Mobile Mapping System (SiOUMMS) on the same ship, and a position deviation correction method is designed to improve the accuracy of the pipeline detection positioning.
Abstract: Submarine pipelines are important resource delivery devices between land and ocean. For safety reasons, pipelines are often embedded beneath the seabed at a certain depth, to reduce the risk of direct damage to the pipeline. In the past, various kinds of detection equipment have been used for pipeline inspection, to ensure the normal operation of pipelines in practical applications. Acoustic detection technology is the dominant method to monitor buried submarine pipelines. Extracting and integrating the information in acoustic images, such as the route and burial depth, can help to monitor the status of a pipeline. However, most of the existing methods are based on limited parameters, and they cannot be used to precisely detect and locate a submarine pipeline under complex conditions. In this study, a multi-sensor surveying system was used, which integrates a sub-bottom profiler (SBP) and the Shipborne Over- and Under-Water Integrated Mobile Mapping System (SiOUMMS) on the same ship. The data acquired in this system include acoustic profile images and the over- and under-water topography of the pipeline route area. We also designed a position deviation correction method to improve the accuracy of the pipeline detection positioning, i.e., pipeline positioning correction in the real-time kinematic (RTK) positioning data and pipeline horizontal route correction in the integrated data. Compared with the uncorrected pipeline detection positioning result, the reliability of the pipeline inspection result is greatly improved, and the effectiveness and merit of the proposed method are clearly demonstrated. Finally, we conducted a buried pipeline safety assessment for the installation of newly designed wharf piles at Mawan Port of Shenzhen, China, where the results showed that one of the first rows of wharf piles would collide with the sewage pipeline.
27 citations
TL;DR: In this paper, the authors proposed that strike-slip movement along the Red River Fault and ridge jump of the South China Sea caused the coeval Baiyun-Liwan submarine slide, which extends for over 250 km and the total affected area of the slide is up to ~35,000-40,000 km2.
Abstract: Submarine landslides can be tremendous in scale. They are one of the most important processes for global sediment fluxes and tsunami generation. However, studies of prodigious submarine landslides remain insufficient. In this review paper, we compile, summarize, and reanalyze the results of previous studies. Based on this reanalysis, we discover the giant Baiyun–Liwan submarine slide in the Pearl River Mouth Basin, South China Sea. We describe three concurrent pieces of evidence from ~23 Ma to 24 Ma, the Oligocene–Miocene boundary, for this landslide: the shoreward shift of the shelf break in the Baiyun Sag, the slump deposition to the southeast, and the abrupt decrease in the accumulation rate on the lower continental slope. This landslide extends for over 250 km, and the total affected area of the slide is up to ~35,000–40,000 km2. The scale of the landslide is similar to that of the Storegga slide, which has long been considered to be the largest landslide on earth. We suggest that strike–slip movement along the Red River Fault and ridge jump of the South China Sea caused the coeval Baiyun–Liwan submarine slide. The identification of the giant landslide will promote the understanding of not only its associated geohazards but also the steep rise of the Himalayan orogeny and marine engineering. More attention needs to be paid to areas with repeated submarine landslides and offshore installations.
TL;DR: In this paper, a numerical model that integrates optimization of well paths and surface facilities in shallow-water offshore oil and gas field developments is presented, which determines the locations, size and number of offshore platforms, tie-in and separation facilities, as well as optimizing the well path and pipeline routes.
TL;DR: In this article, the authors present a numerical investigation of the scour phenomenon around a submarine pipeline using SedFoam, a two-phase flow model for sediment transport implemented in the open source Computational Fluid Dynamics (CFD) toolbox OpenFOAM.
Abstract: This paper presents a numerical investigation of the scour phenomenon around a submarine pipeline. The numerical simulations are performed using SedFoam, a two-phase flow model for sediment transport implemented in the open source Computational Fluid Dynamics (CFD) toolbox OpenFOAM. The paper focuses on the sensitivity of the granular stress model and the turbulence model with respect to the predictive capability of the two-phase flow model. The quality of the simulation results is estimated using a statistical estimator: the Brier Skill Score. The numerical results show no sensitivity to the granular stress model. However, the results strongly depend on the choice of the turbulence model, especially through the different implementations of the cross-diffusion term in the dissipation equation between the k − e and the k − ω 2006 models. The influence of the cross-diffusion term tends to indicate that the sediment transport layer behaves more as a shear layer than as a boundary layer, for which the k − e model is more suitable.
TL;DR: In this article, the authors used inspection footage from eight pipelines to quantify the presence and abundance of species and features listed under a number of EU and UK conservation designations; 12 such features and species were observed on the pipelines or neighboring sediments.
Abstract: Oil and gas pipelines that lie exposed on the seabed can function as “artificial reefs”, providing habitat for fish and benthic species, including some that are listed under conservation designations. As the offshore hydrocarbon industry matures, operators and national governments must decide whether decommissioned pipelines should be left in situ or removed for onshore disposal. In most jurisdictions, there is a requirement to evaluate the environmental consequences of different pipeline decommissioning options in a comparative assessment. To do this effectively requires an understanding of the associations between pipelines and fauna. Pipeline operators routinely collect video footage for inspection and maintenance purposes using remotely operated vehicles (ROV). This footage has the potential to provide insight into interactions between the marine environment and offshore pipelines. This study uses inspection footage from eight pipelines to quantify the presence and abundance of species and features listed under a number of EU and UK conservation designations; 12 such features and species were observed on the pipelines or neighboring sediments. The soft coral Alcyonium digtatum was present in the highest densities on pipelines located on mud, while Sabellaria sp. and Echinus esculentus were more common on pipelines in sand. Gadoids, anemones and hermit crabs were also frequently observed around pipelines. The study also suggests that faunal identification from ROV footage depended on image resolution, ROV speed and altitude, and lighting, and taxa <50 mm in size could not be reliably classified. The results suggest that removal of pipelines will remove established colonies of epibenthic species, some of which have conservation value. The ecological significance of this loss, however, must be weighed against the broader considerations during pipeline decommissioning including cost, technical feasibility and impacts to other marine users.
TL;DR: In this article, the authors analyzed a multifaceted dataset of offshore seismic sub-bottom profiles, multibeam and side-scan sonar images of the seafloor, radon measurements of seawater and groundwater, and onshore ground-penetrating radar and refraction seismic profiles in order to establish the detailed stratigraphical architecture of a high-latitude submarine groundwater discharge (SGD) site, which is connected to the Late-Pleistocene First Salpausselka icemarginal formation on the Hanko Peninsula in Finland.
Abstract: . Submarine groundwater discharge (SGD) has been implicated as a significant source of nutrients and potentially harmful substances to the coastal sea. Although the number of reported SGD sites has increased recently, their stratigraphical architecture and aquifer geometry are rarely investigated in detail. This study analyses a multifaceted dataset of offshore seismic sub-bottom profiles, multibeam and side-scan sonar images of the seafloor, radon measurements of seawater and groundwater, and onshore ground-penetrating radar and refraction seismic profiles in order to establish the detailed stratigraphical architecture of a high-latitude SGD site, which is connected to the Late-Pleistocene First Salpausselka ice-marginal formation on the Hanko Peninsula in Finland. The studied location is characterized by a sandy beach, a sandy shore platform that extends 100–250 m seaward sloping gently to ca. 4 m water depth, and a steep slope to ca. 17 m water depth within ca. 50 m distance. The onshore radar and offshore seismic profiles are correlated based on unconformities, following the allostratigraphical approach. The aquifer is hosted in the distal sand-dominated part of a subaqueous ice-contact fan. It is interpreted that coarse sand interbeds and lenses in the distal fan deposits, and, potentially, sandy couplet layers in the overlying glaciolacustrine rhythmite, provide conduits for localized groundwater flow. The SGD takes place predominantly through pockmarks on the seafloor, which are documented on the shore platform slope by multibeam and side-scan sonar images. Elevated radon-222 activity concentrations measured 1 m above seafloor confirm SGD from two pockmarks in fine sand sediments, whereas there was no discharge from a third pockmark that was covered with a thin organic-rich mud layer. The thorough understanding of the local stratigraphy and the geometry and composition of the aquifer that have been acquired in this study are crucial for successful hydrogeological modelling and flux studies at the SGD site.
TL;DR: The risk posed by seabed instability is of increasing significance as offshore activities including oil and gas developments continue to expand in this century as mentioned in this paper, and many studies have considered runout...
Abstract: The risk posed by seabed instability is of increasing significance as offshore activities including oil and gas developments continue to expand in this century. Many studies have considered runout ...
TL;DR: In this article, a tsunami-like wave generated based on a real-world tsunami wave profile recorded during a 2011 tsunami in Japan has been applied to study the impacts of tsunami waves on submarine pipelines, although the hydrodynamic characteristics and wave properties drastically differ from those of real world tsunami waves.
Abstract: Submarine pipelines have been extensively used for marine oil and gas extraction due to their high efficiency, safety, and low price. However, submarine pipelines are vulnerable to extreme waves (i.e., tsunami waves). Previous research has often used solitary waves as a basis for studying the impacts of tsunami waves on submarine pipelines, although the hydrodynamic characteristics and wave properties drastically differ from those of real-world tsunami waves. This paper numerically investigates the hydrodynamic characteristics of tsunami waves interacting with submarine pipelines, but instead uses an improved wave model to generate a tsunami-like wave that more closely resembles those encountered in the real-world. The tsunami-like wave generated based on a real-world tsunami wave profile recorded during a 2011 tsunami in Japan has been applied. Given the same wave height, simulation results show that peak hydrodynamic forces of the tsunami-like wave are greater than those of the solitary wave. Meanwhile, the duration of the acting force under the tsunami-like wave is much longer than that of the solitary wave. These findings underline the basic reasons for the destructive power of tsunamis. It is also noted that the hydrodynamic forces of the pipeline under the tsunami-like wave increase with wave height, but will decrease as water depth increases. In addition to the single pipeline, the complicated hydrodynamic characteristics of pipelines in tandem arrangement have been also numerically studied. It is believed that the findings drawn from this paper can enhance our understanding of the induced forces on submarine pipelines under extreme tsunami waves.
TL;DR: Optimisation of technology and understanding the underlying biology of S. latissima is needed for cultivation in exposed conditions at the southern distribution limit of the species, with growth rates of 3.3%–4.5% day−1 between January and May, while withstanding high wave heights.
Abstract: Implementation of open sea seaweed aquaculture has been pursued in Europe for high biomass production to be used for different purposes, including the biorefinery pipeline. Offshore cultiva...
TL;DR: In this article, the response of pipelines to transverse impact loads by dropped objects is investigated experimentally and numerically, and a finite element numerical model is established to determine the dynamic response and it is validated against the experimental results, showing good consistency.
TL;DR: In this paper, an artificial neural network (AN) was used to predict the liquefaction of sandy porous soil under earthquake waves, which is the most important feature governing the serviceability of underground pipelines.
Abstract: Liquefaction of sandy porous soil under earthquake waves is the most important feature governing the serviceability of underground pipelines. In this study, an artificial neural network (AN...
TL;DR: In this article, the relationship between the temperature and the buckling height during the thermal vertical buckling of the third-order mode of pipeline was analyzed and the finite element method was utilized to model and simulate the pipeline.
01 Oct 2019
TL;DR: In this paper, the authors outline and illustrate a new partial-differential-equation methodology for characterizing and modeling plastic transports in time and space (4D), showcasing results for Massachusetts Bay.
Abstract: To cleanup marine plastics, accurate modeling is needed. We outline and illustrate a new partial-differential-equation methodology for characterizing and modeling plastic transports in time and space (4D), showcasing results for Massachusetts Bay. We couple our primitive equation model for ocean dynamics with our composition based advection for Lagrangian transport. We show that the ocean physics predictions have skill by comparison with synoptic data. We predict the fate of plastics originating from four sources: rivers, beach and nearshore, local Bay, and remote offshore. We analyze the transport patterns and the regions where plastics accumulate, comparing results with and without plastic settling. Simulations agree with existing debris and plastics data. They also show new results: (i) Currents set-up by wind events strongly affect floating plastics. Winds can for example prevent Merrimack outflows reaching the Bay; (ii) There is significant chaotic stirring between nearshore and offshore floating plastics as explained by ridges of Lagrangian Coherent Structures (LCSs); (iii) With 4D plastic motions and settling, plastics from the Merrimack and nearshore regions can settle to the seabed before offshore advection; (iv) Internal waves and tides can bring plastics downward and out of main currents, leading to settling to the deep bottom. (v) Attractive LCSs ridges are frequent in the northern Cape Cod Bay, west of the South Shore, and southern Stellwagen Bank. They lead to plastic accumulation and sinking along thin subduction zones.
TL;DR: In this paper, the authors used swath-bathymetric data from the inner shelf and fjords of northwest and southeast Greenland to analyze the controls on the formation of submarine channels offshore of numerous marine-terminating glaciers.
TL;DR: In this paper, a mesh-free model was developed to investigate the wave-induced soil response in the vicinity of a submarine pipeline, where Reynolds-Averaged Navier-Stokes (RANS) equations were employed to simulate the wave loading, while Biot's consolidation equations were adopted to investigate wave-driven soil response.
Abstract: The evaluation of the wave-induced seabed instability around a submarine pipeline is particularly important for coastal engineers involved in the design of pipelines protection. Unlike previous studies, a meshfree model is developed to investigate the wave-induced soil response in the vicinity of a submarine pipeline. In the present model, Reynolds-Averaged Navier-Stokes (RANS) equations are employed to simulate the wave loading, while Biot’s consolidation equations are adopted to investigate the wave-induced soil response. Momentary liquefaction around an offshore pipeline in a trench is examined. Validation of the present seabed model was conducted by comparing with the analytical solution, experimental data, and numerical models available in the literature, which demonstrates the capacity of the present model. Based on the newly proposed model, a parametric study is carried out to investigate the influence of soil properties and wave characteristics for the soil response around the pipeline. The numerical results conclude that the liquefaction depth at the bottom of the pipeline increases with increasing water period (T) and wave height (H), but decreases as backfilled depth ( H b ), degree of saturation ( S r ) and soil permeability (K) increase.
TL;DR: In this article, a plane-strain numerical analysis of pipe-soil interaction under cyclic wave actions is presented for the stability analysis of submarine pipelines in sandy seabed.
TL;DR: In this paper, the authors used a high-speed camera to obtain an improved understanding of the mechanics of scour around a forced vibrating pipeline in quiescent water and found that the magnitudes of flow velocity, vorticities, and turbulence fluctuations are strongly dependent on the frequency of the vibrating pipelines.
TL;DR: A feasible numerical method for a structural analysis of a pipeline configuration during the installation process and the comparison with Abaqus shows that for the selected parameters the assumption that the pipeline is inextensible and unshearable is very reasonable.
TL;DR: In this paper, the impact of pipe-soil interaction on the pipe response was examined analytically by a seabed-laid offshore pipeline subjected to a lateral kinematic distress due to a submarine landslide or a debris flow.
TL;DR: In this paper, the mechanisms and time scales of fresh groundwater preservation are examined using numerical simulations based on a geologically representative model of the New Jersey shelf, USA, using two-dimensional depth-migrated seismic and well data.
Abstract: The existence of submarine fresh groundwater has been recorded at continental shelves worldwide. The dynamic preservation and lifetime of fresh groundwater in the offshore environment remains an open hydrogeological problem. The mechanisms and time scales of fresh groundwater preservation are examined using numerical simulations based on a geologically representative model of the New Jersey shelf, USA. Utilizing two-dimensional depth-migrated seismic and well data, a detailed hydrogeological model is built, with a vertical resolution of 10 m. The model captures the highly heterogeneous shelf environment and accounts for porosity compaction trends derived from core data. The results show transient coupled simulations of groundwater flow and heat and salt transport from the late Pleistocene until present day and projected 18,000 years into the future. They reveal freshwater preservation patterns and yield simulated borehole salinity profiles broadly consistent with field observations. The simulations show that freshwater intervals of a thickness of 200–300 m and lateral extent of tens of kilometers may have been preserved from the Last Glacial Maximum until today. It was found that approximately 30–45% of the initial freshwater volume remains preserved after 12,000 years, depending on the recharge boundary condition. The preserved volume ranges between 15 and 30% after 30,000 years. These results improve the understanding of submarine preservation of fresh groundwater through an interdisciplinary approach which integrates seismic imaging, hydrogeological modeling and high-performance numerical simulation.
TL;DR: In this article, the probability of damage to a submarine pipeline due to a box-shaped dropped object has been calculated in terms of dropped object impact frequency and energy transfer according to the DNV-RP-F107.
Abstract: One of the safest and the most economical methods to transfer oil and gas is pipeline system. Prediction and prevention of pipeline failures during its assessed lifecycle has considerable importance. The dropped object is one of the accidental scenarios in the failure of the submarine pipelines. In this paper, using Monte Carlo Sampling, the probability of damage to a submarine pipeline due to a box-shaped dropped object has been calculated in terms of dropped object impact frequency and energy transfer according to the DNV-RP-F107. Finally, Reliability sensitivity analysis considering random variables is carried out to determine the effect intensity of each parameter on damage probability. It is concluded that impact area and drag coefficient have the highest sensitivity and mass and add mass coefficient have the lowest sensitivity on probability of failure.