scholarly journals A comparison of two remotely operated vehicle (ROV) survey methods used to estimate fish assemblages and densities around a California oil platform

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242017
Author(s):  
Milton S. Love ◽  
Mary M. Nishimoto ◽  
Scott Clark ◽  
Li Kui ◽  
Azivy Aziz ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Oil And Gas ◽  
Fish Assemblages ◽  
Survey Methods ◽  
Fish Habitat ◽  
Species Assemblages ◽  
Fish Diversity ◽  
Structural Method ◽  
Remotely Operated Vehicle ◽  
Integrity Assessment

Offshore oil and gas platforms have a finite life of production operations. Once production ceases, decommissioning options for the platform are assessed. The role that a platform’s jacket plays as fish habitat can inform the decommissioning decision. In this study, conducted along the crossbeams of a California platform jacket and using an ROV, we compared estimates of fish diversity and densities determined from a targeted “biological” survey with those from a replicated “structural” survey. We found that the water column fish species assemblages characterized by the two methods were similar. By contrast, the two survey methods yielded different species assemblages inhabiting the crossbeam at the platform jacket base. This difference occurred because, at least off California, the platform jacket base species diversity tends to be highest where the bottom crossbeam is undercut, creating sheltering sites for many species. Because the structural method inadequately imaged the seafloor-crossbeam interface, particularly where a gap occurred between crossbeam and seafloor, substantial numbers of fishes were not visible. While we cannot extrapolate from this study to all platforms’ worldwide, it is clear that routine platform structural integrity surveys may be a valuable source for opportunistic marine community surveys. Intentional planning of the structural survey to incorporate relatively minor variations (e.g., maintaining fixed ROV distance from the infrastructure and consistent 90° camera angle) coupled with a deliberate consideration of the platform ecology (e.g., positioning the ROV to capture the seafloor-crossbeam interface) can substantially improve the effects on fish assemblage assessments from routine structural surveys without compromising the integrity assessment. We suggest that these biases should be both acknowledged and, understood when using routine structural surveys to inform platform ecology assessment. Additional consideration may be given to structural surveys that incorporate incremental adjustments to provide better data applicability to biological assessments.

FISH DIVERSITY IN THE DOWNSTREAM REGION OF CIPANAS RIVER INDRAMAYU, WEST JAVA INDONESIA

Zoo Indonesia ◽  
2020 ◽  
Vol 29 (1) ◽  
Author(s):  
Titin Herawati ◽  
Gema Wahyudewantoro ◽  
Yuli Andriani ◽  
Heti Herawati ◽  
Naomi Masnida Yunisia Siregar
Keyword(s):  
Water Quality ◽  
Census Data ◽  
Fish Assemblages ◽  
Survey Methods ◽  
Upstream Region ◽  
Fish Diversity ◽  
West Java ◽  
Fish Collection ◽  
Java Sea ◽  
Downstream Area

Cipanas River is one river in West Java where its upstream region in Tampomas Mountain, Sumedang and it is emptied into the Java Sea, Indramayu. The study was aimed to investigate fish diversity in the downstream area of Cipanas River. The study was conducted by survey methods with census data collection techniques, taken place at 3 stations of Santing, Tempalong, and Cemara of Indramayu Regency. The parameters measured consisted water quality and fish assemblages. Water quality was measured referring to standard laboratory protocol, and fish collection was made by case net with different mesh sizes. The results showed that water quality conditions of the Cipanas River downstream was suitable for inhabiting fishes. There were as many as 548 individual fishes caught belonging to 21 species, 16 genera, and 14 families. Fish diversity was categorized as medium with 1.6 ≤ H ’≤ 2.2 indicating fairly good community structure, and the Evenness index was 0.81 ≤ E ≤ 0.86 to show highly evenly distributed.

scholarly journals Fish densities associated with structural elements of oil and gas platforms in southern California

2019 ◽  
Vol 95 (4) ◽  
pp. 639-656 ◽  
Author(s):  
Erin L Meyer-Gutbrod ◽  
Li Kui ◽  
Mary M Nishimoto ◽  
Milton S Love ◽  
Donna M Schroeder ◽  
...  
Keyword(s):  
Habitat Use ◽  
Southern California ◽  
Oil And Gas ◽  
Fish Assemblages ◽  
Fish Habitat ◽  
Artificial Reef ◽  
Offshore Structures ◽  
Structural Elements ◽  
Structural Element ◽  
Young Of The Year

There are thousands of offshore oil and gas platforms worldwide that will eventually become obsolete, and one popular decommissioning alternative is the "rigs to reefs" conversion that designates all or a portion of the underwater infrastructure as an artificial reef, thereby reducing the burden of infrastructure removal. The unique architecture of each platform may influence the size and structure of the associated fish assemblage if different structural elements form distinct habitats for fishes. Using scuba survey data from 11 southern California platforms from 1995 to 2000, we examined fish assemblages associated with structural elements of the structure, including the major horizontal crossbeams outside of the jacket, vertical jacket legs, and horizontal crossbeams that span the jacket interior. Patterns of habitat association were examined among three depth zones: shallow (<16.8 m), midwater (16.8–26 m), and deep (>26 m); and between two life stages: young- of-the-year and non-young-of-the-year. Fish densities tended to be greatest along horizontal beams spanning the jacket interior, relative to either horizontal or vertical beams along the jacket exterior, indicating that the position of the habitat within the overall structure is an important characteristic affecting fish habitat use. Fish densities were also higher in transects centered directly over a vertical or horizontal beam relative to transects that did not contain a structural element. These results contribute to the understanding of fish habitat use on existing artificial reefs, and can inform platform decommissioning decisions as well as the design of new offshore structures intended to increase fish production.

Investigation of Strain-Based Failure Assessment Based on Reference Strain Method for Welded Pipes

2019 ◽  
Author(s):  
Jae Sung Lee ◽  
Myung Hyun Kim
Keyword(s):  
Reference Strain ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Effective Means ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Evaluation Procedure ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Strain Method

Abstract Pipelines are effective means to transport oil and gas. It is essential to maintain the safety of pipelines with the increasing demand for oil and gas resource. Welded pipelines may suffer damage such as cracks during installation and operation, and the consequence evaluation for such damage is very important. Engineering critical assessment (ECA) is the evaluation procedure for structures with flaws and has been widely applied for assessing the pipeline integrity. Although main standards of structural integrity assessment including BS 7910 are stress-based ECA, it is known to produce overly conservative results. In this regard, strain-based ECA has been recently developed. One of the methods for improving the accuracy of strain-based ECA is the reference strain method. However, only few researches with reference strain method applied to welded pipes are available. Therefore, in this study, a numerical analysis based on the strain-based ECA is performed for strength mismatched girth welded joints with a circumferentially oriented internal surface crack. Equivalent stress-strain curve in BS7910 is employed to reflect the strength mismatch effects in the reference strain. This paper compares the results from the reference strain method and finite element analysis: J-integral and reference strain. Strain capacity of the reference strain method with strength mismatch is also discussed against stress-based ECA.

scholarly journals Enhanced ROV Survey of Tropical Fish and Benthic Communities Associated With Shallow Oil and Gas Platforms

2021 ◽  
Author(s):  
Dianne L. McLean ◽  
Matthew Birt
Keyword(s):  
Oil And Gas ◽  
Fish Assemblages ◽  
Tropical Fish ◽  
Relative Mass ◽  
High Definition ◽  
Remotely Operated Vehicle ◽  
Natural Habitats ◽  
North West ◽  
Stereo Video ◽  
Encrusting Sponges

Abstract Understanding the ecology of oil and gas infrastructure in our oceans is required to inform decommissioning such that environmental impacts are minimised, and benefits maximised. This study equipped an industrial remotely operated vehicle (ROV) with a stereo-video system and collected seven hours of high-definition imagery of two platform jackets, for assessments of benthic (type, density, complexity) and fish assemblages (richness, abundance, length) present. Harriet Alpha (25 m depth) and Gibson/South Plato (8 m depth) are located ca. 120 km offshore of north-west Australia, adjacent to Varanus Island. Twenty-one ‘classes’ of benthic biota were observed in high density, with little bare structure on either platform. Encrusting sponges (average 19% cover per virtual quadrat), barnacles (17%) and sponges (16%) were common on Gibson/South Plato while encrusting sponges (16%) and macroalgae (18%) were ubiquitous on quadrats on Harriet Alpha. The sun coral Tubastraea faulkneri was common on Harriet Alpha (38% of quadrats), though coverage was low (<6%). A total of 102 fish species from 27 families were observed. This included 33 fishery target species with an estimated relative mass of 116 kg on Gibson/South Plato and 299 kg on Harriet Alpha, with these species typically concentrated near the seafloor-structure interface. Differences in benthic biota communities present on each platform likely reflect spatial variations in oceanographic processes, proximity to natural habitats and the age, configuration, cleaning regime and depth of the structures themselves. This study demonstrates the value of adding stereo-video systems to ROVs to undertake rapid scientific surveys of oil and gas infrastructure.

Comparing the Utility of Industry ROV and Hybrid-AUV Imagery for Surveys of Fish Along a Subsea Pipeline

2020 ◽  
Vol 54 (3) ◽  
pp. 33-42
Author(s):  
Todd Bond ◽  
Jane Prince ◽  
Dianne L. McLean ◽  
Julian C. Partridge
Keyword(s):  
Oil And Gas ◽  
Fish Assemblages ◽  
Survey Methods ◽  
Autonomous Underwater Vehicles ◽  
Time Of Day ◽  
High Definition ◽  
Subsea Pipeline ◽  
Pipeline Inspection ◽  
Video Footage ◽  
Offshore Oil And Gas

AbstractIn recent years, video footage obtained from routine industry surveys using remotely operated vehicles (ROVs) has been used to assess fish assemblages associated with offshore oil and gas infrastructure. However, as industry moves towards using autonomous underwater vehicles (AUVs), it is important to understand how such a change may affect assessments of fish assemblages and whether these data collected from AUVs can be directly compared to those collected from historic and future ROV footage. In an extremely rare opportunity, we compare fish assemblages surveyed by an industrial ROV and an industrial hybrid-AUV (H-AUV) along the same 2,060-m section of subsea pipeline, at the same time of day, within 1 day of each other. A total of 206 transects, each 20 m in length, were analyzed, recording 406 fish from 10 species. The H-AUV recorded all 10 fish species, while the ROV recorded seven. Mean species richness was ~4% higher for H-AUV, and mean abundance was ~21% higher for ROV; these differences can be considered negligible. Multivariate analysis revealed nonsignificant differences in species composition between survey methods. This result suggests that future surveys of fish at this pipeline using a similar H-AUV can yield comparable results to ROV and, as such, facilitate comparison to historical ROV imagery. Future surveys of pipelines with AUV should consider adding extra lighting and high-definition cameras onto booms similar to those operating on ROVs, which will provide a useful field of view into pipeline spans and make it easier to identify fish. Our study provides insight into the utility and comparability of industry ROV and AUV pipeline inspection footage for the assessment of fish assemblages associated with subsea pipelines, which is used to inform policies and practices on the installation and decommissioning of subsea infrastructure.

Structural Strength Assessment of Dented Steel Tubular Members

2021 ◽  
Author(s):  
S. Saad-Eldeen ◽  
Mahmoud Helal ◽  
Elsayed Fathallah
Keyword(s):  
Residual Strength ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Geometrical Parameters ◽  
Element Analysis ◽  
Strength Assessment ◽  
Operational Conditions ◽  
Integrity Assessment ◽  
Modes Of Failure ◽  
Ultimate Load Carrying Capacity

Abstract Tubular members are widely used in oil and gas offshore production and drilling structures either fixed or mobile units. Due to complex operational conditions, the tubular members are subjected to both age and mechanical related damage, which in turn affect the ability of the structure to withstand the applied loads. This motivates the importance of investigating the behavior of tubular members considering the presence of dentation resulting from collision or falling objects and consequently assessing the residual strength of the damaged members accurately. A series of finite element analysis are performed to study the pre- and post-ultimate strength behavior of intact and locally dented un-stiffened steel tubular members subjected to four-point bending. The effects of dent geometrical parameters; length, width, depth, orientation, and location on the ultimate load carrying capacity are analyzed. The ratio between the diameters to the shell thickness is varied, where combined local and global initial imperfections are considered. Buckling and post collapse analysis as well as modes of failure are studied. Parametric diagrams for the ultimate residual strength as a function of dent geometry and the location of damage are also presented. Several concluding remarks are stated which benefit the structural integrity assessment of tubular steel members.

Integrity Assessment and Repair Techniques of Flexible Risers

2006 ◽  
Author(s):  
Mauro G. Marinho ◽  
Joilson M. dos Santos ◽  
Ricardo de O. Carneval
Keyword(s):  
Structural Integrity ◽  
Oil And Gas ◽  
Production Systems ◽  
Injection Pressure ◽  
Gas Transfer ◽  
Flow Measurements ◽  
Integrity Assessment ◽  
Flexible Pipes ◽  
Periodic Inspections ◽  
Repair Techniques

Deep water oil and gas exploitation in Brazil remarkably increased the utilization of flexible pipes in conjunction with floating production systems. In Campos Basin nowadays oil and gas transfer, water and gas injection and well control and monitoring are carried out almost entirely by flexible pipes, including risers, flowlines and umbilicals. Periodic inspections have detected a considerable incidence of damage in the top section of risers, which may affect their structural integrity and eventually induce different failure mechanisms. These include mostly external sheath damage, corrosion and/or fatigue-induced damage to the tensile armours and torsional instability. These damages are generally originated during installation or, more frequently, during operation due to contact with another riser or the platform structure. In order to mitigate the progression of these damages, besides periodic inspections, repair techniques were developed for both emerged and submerged riser sections. Apart from the inspection program, surface monitoring procedures, such as nitrogen injection, pressure monitoring and flow measurements in the annular space are being implemented, for a continuous flexible riser integrity assessment. This paper describes and evaluates these techniques, as well as reports the results obtained from field experience.

Fracture Assessment of the High Strength Super-Martensitic Stainless Steel Welds by SINTAP Defect Assessment Procedure

2003 ◽  
Author(s):  
A. K. Motarjemi ◽  
M. Koc¸ak ◽  
R. Segar ◽  
S. Riekehr
Keyword(s):  
Stainless Steel ◽  
Carrying Capacity ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Welding Process ◽  
Assessment Procedure ◽  
Load Carrying Capacity ◽  
Deformation And Failure ◽  
Integrity Assessment ◽  
Load Carrying

13% Cr supermartensitic stainless steel is an adequate substitute material for the conventional carbon and duplex stainless steel pipes for mild corrosive environments in the oil and gas industries. By development of these new steel and respective welding technologies, structural integrity analysis of the welded pipes, is essential and a challenging task. Depending on the welding process, filler wire used, the deformation and failure behaviours of the welded pipes could be different. In this study, fitness for service analysis verified with Submerged Arc welded Middle Tension, M(T), plates as well as for the reeling deformation during the pipe-laying process. This was done by applying analysis Levels 0, I, II and III of a recently developed European Structural Integrity Assessment Procedure (SINTAP). The goal was first of all to verify SINTAP’s load-carrying capacity predictions for welded M(T) specimens (wide plates) by comparing them with corresponding experimental data. SINTAP was also used for estimating the maximum tolerable crack size within the base or weld regions under about 2.7% applied strain, which is the strain equal to the reeling process. The estimated load-carrying capacity of the plates were found on the safe side with acceptable conservatism for all the SINTAP analysis Levels.

scholarly journals Guest Editorial: Recent Advances in Design and Structural Integrity of Pressure Vessels, Piping and Components

2021 ◽  
Author(s):  
Nam-Su Huh ◽  
Yun-Jae Kim ◽  
Naoya Tada
Keyword(s):  
Guest Editorial ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Pressure Vessels ◽  
Special Issue ◽  
New Techniques ◽  
Research Results ◽  
Integrity Assessment ◽  
Recent Advances

Abstract The design and structural integrity evaluation of pressure retaining equipment are crucial elements in the nuclear, oil and gas industries. Accordingly, many research has been done to improve the accuracy of design and structural integrity assessment methodologies and to develop new techniques and procedures. In this special issue, it is intended to introduce the latest research results on these subjects. The papers in this issue were collected from two groups.

scholarly journals Decommissioning impacts on biotic assemblages associated with shell mounds beneath southern California offshore oil and gas platforms

2019 ◽  
Vol 95 (4) ◽  
pp. 683-702 ◽  
Author(s):  
Erin L Meyer-Gutbrod ◽  
Milton S Love ◽  
Jeremy T Claisse ◽  
Henry M Page ◽  
Donna M Schroeder ◽  
...  
Keyword(s):  
Species Composition ◽  
Southern California ◽  
Oil And Gas ◽  
Fish Assemblages ◽  
Ecological Value ◽  
Remotely Operated Vehicle ◽  
Wide Range ◽  
Shell Mounds ◽  
Offshore Oil And Gas ◽  
Offshore Oil

The decommissioning of southern California offshore oil and gas platforms will create major economic, engineering, and environmental challenges in the next decade. Platform jackets, conductors, and shell mounds often host a diverse and productive marine community, and among the myriad considerations associated with decommissioning planning, platform operators and federal and state regulatory agencies will consider the ecological value of existing underwater structures as artificial reefs. In the event of partial removal of platform structure, fish assemblages on decommissioned platforms may remain unchanged in areas where structure is left intact. However, on the seafloor beneath the platforms, a mound of debris often called the shell mound will likely change over time if the supply of falling mussels and other organisms from the productive surface part of the structure is removed. In this study, we review shell mound research relevant to decommissioning, including mound formation, contaminant loads, associated biological communities, and transitions following the removal of platform structures at four sites. To address the gap in knowledge of shell mound fish community structure, we used manned submersible and remotely operated vehicle surveys from 1997 to 2013 to estimate the biomass, density, species composition and similarity between shell mounds at 22 southern California platforms. We found a wide range of variability in fish density and shell mound areal extent. Species composition also varied among sites, with three significant community clusters primarily distinguished by species depth preferences. These results will help inform a comprehensive net environmental benefit analysis of southern California offshore platform decommissioning alternatives.

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