Stability of offshore structures in shallow water depth

2011 ◽  
Vol 2 (2) ◽  
pp. 320-333
Author(s):  
F. Van den Abeele ◽  
J. Vande Voorde
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Fossil Fuels ◽  
Oil And Gas ◽  
Structural Response ◽  
Offshore Structures ◽  
Exploration And Production ◽  
Subsea Pipelines ◽  
Wave Induced ◽  
Shallow Water Depth

The worldwide demand for energy, and in particular fossil fuels, keeps pushing the boundaries of offshoreengineering. Oil and gas majors are conducting their exploration and production activities in remotelocations and water depths exceeding 3000 meters. Such challenging conditions call for enhancedengineering techniques to cope with the risks of collapse, fatigue and pressure containment.On the other hand, offshore structures in shallow water depth (up to 100 meter) require a different anddedicated approach. Such structures are less prone to unstable collapse, but are often subjected to higherflow velocities, induced by both tides and waves. In this paper, numerical tools and utilities to study thestability of offshore structures in shallow water depth are reviewed, and three case studies are provided.First, the Coupled Eulerian Lagrangian (CEL) approach is demonstrated to combine the effects of fluid flowon the structural response of offshore structures. This approach is used to predict fluid flow aroundsubmersible platforms and jack-up rigs.Then, a Computational Fluid Dynamics (CFD) analysis is performed to calculate the turbulent Von Karmanstreet in the wake of subsea structures. At higher Reynolds numbers, this turbulent flow can give rise tovortex shedding and hence cyclic loading. Fluid structure interaction is applied to investigate the dynamicsof submarine risers, and evaluate the susceptibility of vortex induced vibrations.As a third case study, a hydrodynamic analysis is conducted to assess the combined effects of steadycurrent and oscillatory wave-induced flow on submerged structures. At the end of this paper, such ananalysis is performed to calculate drag, lift and inertia forces on partially buried subsea pipelines.

Accelerating oil and gas investment and reserves by design

2018 ◽  
Vol 58 (2) ◽  
pp. 557
Author(s):  
Barry A. Goldstein
Keyword(s):  
Natural Gas ◽  
Fossil Fuels ◽  
Oil And Gas ◽  
South Australia ◽  
Land Access ◽  
Oil And Gas Exploration ◽  
Oil And Gas Producers ◽  
Crude Oil Prices ◽  
Exploration And Production ◽  
Oil And Gas Operations

Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passion, they cannot alter the state of facts and evidence (Adams 1770). Some people unfamiliar with upstream petroleum operations, some enterprises keen to sustain uncontested land use, and some people against the use of fossil fuels have and will voice opposition to land access for oil and gas exploration and production. Social and economic concerns have also arisen with Australian domestic gas prices tending towards parity with netbacks from liquefied natural gas (LNG) exports. No doubt, natural gas, LNG and crude-oil prices will vary with local-to-international supply-side and demand-side competition. Hence, well run Australian oil and gas producers deploy stress-tested exploration, delineation and development budgets. With these challenges in mind, successive governments in South Australia have implemented leading-practice legislation, regulation, policies and programs to simultaneously gain and sustain trust with the public and investors with regard to land access for trustworthy oil and gas operations. South Australia’s most recent initiatives to foster reserve growth through welcomed investment in responsible oil and gas operations include the following: a Roundtable for Oil and Gas; evergreen answers to frequently asked questions, grouped retention licences that accelerate investment in the best of play trends; the Plan for ACcelerating Exploration (PACE) Gas Program; and the Oil and Gas Royalty Return Program. Intended and actual outcomes from these initiatives are addressed in this extended abstract.

Polarization lidar for shallow water depth measurement

2010 ◽  
Vol 49 (36) ◽  
pp. 6995 ◽  
Author(s):  
Steven Mitchell ◽  
Jeffrey P. Thayer ◽  
Matthew Hayman
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Depth Measurement ◽  
Shallow Water Depth

scholarly journals Generalized Lyzenga's Predictor of Shallow Water Depth for Multispectral Satellite Imagery

2013 ◽  
Vol 36 (4) ◽  
pp. 365-376 ◽  
Author(s):  
Ariyo Kanno ◽  
Yoji Tanaka ◽  
Akira Kurosawa ◽  
Masahiko Sekine
Keyword(s):  
Shallow Water ◽  
Satellite Imagery ◽  
Water Depth ◽  
Multispectral Satellite Imagery ◽  
Shallow Water Depth

A Modified Matlock–Duffing Model for Two-Dimensional Ice-Induced Vibrations of Offshore Structures With Geometric Nonlinearities

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Hugh McQueen ◽  
Narakorn Srinil
Keyword(s):  
Oil And Gas ◽  
Numerical Models ◽  
Wedge Angle ◽  
Offshore Structures ◽  
Two Dimensional ◽  
Geometric Nonlinearities ◽  
Oil And Gas Exploration ◽  
Nonlinear Stress ◽  
Exploration And Production ◽  
Duffing Model

Oil and gas exploration and production have been expanding in Arctic waters. However, numerical models for predicting the ice-induced vibrations (IIV) of offshore structures are still lacking in the literature. This study aims to develop a mathematical reduced-order model for predicting the two-dimensional IIV of offshore structures with geometric coupling and nonlinearities. A cylindrical structure subject to a moving uniform ice sheet is analyzed using the well-known Matlock model, which, in the present study, is extended and modified to account for a new empirical nonlinear stress–strain rate relationship determining the maximum compressive stress (MCS) of the ice. The model is further developed through the incorporation of ice temperature, brine content, air volume, grain size, ice thickness, and ice wedge angle effects on the ice compressive strength. These allow the effect of multiple ice properties on the ice–structure interaction to be investigated. A further advancement is the inclusion of an equation allowing the length of failed ice at a point of failure to vary with time. A mixture of existing equations and newly proposed empirical relationships is used. Structural geometric nonlinearities are incorporated into the numerical model through the use of Duffing oscillators, a technique previously proposed in vortex-induced vibration studies. The model is validated against results from the literature and provides new insights into IIV responses including the quasi-static, randomlike chaotic, and locked-in motions, depending on the ice velocity and system nonlinearities. This numerical Matlock–Duffing model shows a potential to be used in future IIV analysis of Arctic cylindrical structures, particularly fixed offshore structures, such as lighthouses, gravity bases, and wind turbine monopiles.

The Effect of Sunglint Correction for Estimating Water Depth Using Rationing, Thresholding, and Mean Value Algorithms

Rekayasa ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 39-48
Author(s):  
Luhur Moekti Prayogo ◽  
Abdul Basith
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Mean Value ◽  
Point Of View ◽  
Water Object ◽  
Depth Data ◽  
Central Java ◽  
Depth Extraction ◽  
The Mean ◽  
Shallow Water Depth

Satellite-Derived Bathymetry (SDB) is an alternative for obtaining shallow water depth data. The existence of images with various resolutions, the availability of a complete image band can develop the extraction results. This method is based on the principle of the satellite's visible band to estimate water depth. The mapping of shallow water depth is dependent on water conditions, both its brightness and surface. When the sensor senses a water object, the reflected reflection comes from the surface, and some sensors cannot penetrate the water object. The sun's position and the sensor's point of view when sensing it results in interference from the water surface (Sunglint). The sunglint effect on the image can be reduced by performing RGB band correction with NIR Infrared. This study aims to demonstrate the effect of Sunglint's correction on three SDB approaches, namely Thresholding, Rationing, and Mean Value on Worldview 3 imagery in Karimunjawa Islands, Central Java. This study's results indicate that the Sunglint correction on Worldview 3 imagery affects the depth extraction results. The best results are shown by Sunglint's correction using the Thresholding approach (B2-B7), which produces the best correlation with R2 of 0.7364 and (B7-B2) with R2 = 0.7351. Contrastingly, the lowest correlation was generated using the Mean Value ((B2 + B7) / 2) approach without Sunglint's correction with R2 = 0.4015. So this research proves that the Worldview 3 image with Sunglint correction can provide bathymetry data, especially in shallow waters.

Sign in / Sign up

Export Citation Format

Share Document