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.

scholarly journals ANALYSIS OF THE STATE OF SERVICEABILITY IN THE PROCESS OF WEAR OF ELEMENTS DURING THE OPERATION OF OIL AND GAS PRODUCTION EQUIPMENT

2021 ◽  
Vol 08 (04) ◽  
pp. 87-94
Author(s):  
Sevda Aliyeva Sevda Aliyeva
Keyword(s):  
Oil And Gas ◽  
Production Equipment ◽  
Gas Production ◽  
The State ◽  
Structural Elements ◽  
Structural Element ◽  
Oil And Gas Production ◽  
Total Utility ◽  
Generalized Indicator

The generalized indicator of useful use, depending on the state of individual elements of oil-producing equipment, characterizes the ability of this equipment to perform its function during operation at optimal working time. The generalized indicator of the useful use of operational equipment can be described as the calculated sum of the indicator of the useful use of individual equipment elements. If, during operation, the oil-producing equipment retains its operability due to frequent replacement of its structural and non-structural elements, then such operational equipment is considered by users as outdated. Operating equipment can be divided into 6 categories according to the indicators of suitability. The article analyzes the state of useful use of equipment and, as a result, the total utility of equipment is calculated in accordance with the indicators of useful use by category, and graphs of changes in the state of useful use are constructed. Based on the study of the graphs of the useful use of equipment, it was proposed to conduct an analysis in the following areas: • Evaluation of the design and technological perfection of the equipment by users according to important new parameters. • Determination of equipment compliance with wear standards during operation. Keywords: structural element, wear theory, the usefulness of jam, categories, schedule of changes, reliability.

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.

The Role of Oil and Gas Conductors as Fish Habitat at Two Southern California Offshore Platforms

2021 ◽  
Vol 119 (3) ◽  
Author(s):  
Milton S. Love ◽  
Scott Clark ◽  
Merit McCrea ◽  
Katelin Seeto ◽  
Conner Jainese ◽  
...  
Keyword(s):  
Southern California ◽  
Oil And Gas ◽  
Fish Habitat ◽  
Offshore Platforms

scholarly journals An analysis of the fish assemblages around 23 oil and gas platforms off California with comparisons with natural habitats

2019 ◽  
Vol 95 (4) ◽  
pp. 477-514 ◽  
Author(s):  
Milton S Love ◽  
Jeremy T Claisse ◽  
Alexa Roeper
Keyword(s):  
Oil And Gas ◽  
Fish Assemblages ◽  
Habitat Type ◽  
Geographic Location ◽  
Natural Habitats ◽  
Central California ◽  
Shell Mounds ◽  
Young Of The Year ◽  
Offshore Oil And Gas ◽  
Offshore Oil

Between 1995 and 2013, we surveyed fishes living around 23 California offshore oil and gas platforms (midwaters, bases, and shell mounds) and 70 natural habitats. These platforms were distributed between about Point Arguello, central California, and Huntington Beach, southern California, had seafloor depths between 49 and 363 m, and were surveyed between one and 16 times. A total of 1,526,437 fishes were observed. Fish densities were highest around platform bases, followed by platform midwaters, shell mounds, and natural habitats. Of all fishes observed, 90.4% were in the genus Sebastes. Water depth was the strongest driver of the fish species assemblages, although habitat type and geographic location were also important. Most of the fishes living around platforms and natural habitats were relatively small, primarily ≤20 cm in length. Many of these individuals were the juveniles of larger taxa or the juveniles and adults of dwarf species. Larger fishes were less common and these were most often found around platform bases and on natural habitats. Most young-of-the-year (YOY) fishes occurred at water depths of ≤150 m at all four habitats. At platforms, YOY densities were highest in platform midwaters and bases. On average, densities of these young fishes were somewhat higher compared to natural habitats and it is likely that many, although not all, California platforms play a significant role as nursery grounds for a variety of fishes, particularly for a number of Sebastes species.

scholarly journals IMPACT OF COMPRESSIONAL STRESSES WITHIN THE SOUTH CASPIAN MEGADEPRESSION UPON EVOLUTION AND OIL AND GAS CONTENT OF LOCAL UPLIFTS

2021 ◽  
pp. 75-82
Author(s):  
V. Gurbanov ◽  
N. Narimanov ◽  
G. Nasibov
Keyword(s):  
Oil And Gas ◽  
Gas Content ◽  
Qualitative Assessment ◽  
Arabian Plate ◽  
Structural Elements ◽  
The South ◽  
Structural Element ◽  
North West ◽  
Mud Volcanism ◽  
The Impact

The following structural elements in the South Caspian megadepression (SCMD) have been considered: the interfluve of the Kura and Gabirri, the Absheron and Baku archipelagoes, the Lower Kur depression (LKD) and the Godin massif, that stand out geodynamically, from point of view of structural and tectonic evolution and oil and gas content. To solve this problem, the geodynamic environment of the SCMD has been analyzed based on the geodynamic chart of the Central segment of the Mediterranean folding belt compiled by the author, as well as the orientation chart of compressional stresses in the SCD and the methodology, developed for the first time ever, for their qualitative assessment within the structural elements by means of compiling isomorphic maps. The latter make it possible to determine the intensity and nature of the propagation of compressional stresses, the specifics of their impact on folding, oil and gas generation and formation of hydrocarbon accumulations. The Kur-Gabirri interfluve is situated in the west of the SCMD between the closely located Greater and Lesser Caucasian collisions. It is characterized by oil and gas bearing and potential sublatitudinally oriented linear folds, complicated by faulting and mud volcanism. The values of isolines of the isomorphic map and their density are indicative of high intensity of the north-west oriented compressional stresses here. The Absheron archipelago is a western element of the Absheron-Balkhan residual subduction. According to the isomorphic map with a dense network of isolines of sublatitudinal orientation, the archipelago is complicated by linear folding, as well as thrusts, transverse strike-slip faults, mud volcanism, oil and gas content, and oil and gas manifestations indicating the build-up of intense compressional stresses here. Evolution of folds within the Baku archipelago and the Lower Kur depression took place under the stresses of longitudinal and transverse bending. The faintly pronounced linearity of the compressional stresses is apparently associated with the formation of the Western Board of the SCD in the form of a regional submeridianal uplift. It developed under the impact of compressional stresses arising from the effect of the northeastern projection of the Arabian plate on the Iranian one. LKD is an onshore extension of the Baku archipelago. Its anticline zones, regional faults, mud volcanism and oil and gas content continue in the latter. The Godin Massif is the easternmost structural element of those considered with a faintly pronounced reflected folding of unknown prospects. Isolines of the isomorphic map are not directly associated with local uplifts, which is indicative of the absence of clearly pronounced compressional stresses here. The analysis made it possible to determine the degree of development of compressional stresses, their impact upon formation of the sedimentary section, folding, mud volcanism and oil and gas content of the considered structural elements.

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.

scholarly journals The role of jacket complexity in structuring fish assemblages in the midwaters of two California oil and gas platforms

2019 ◽  
Vol 95 (4) ◽  
pp. 597-616 ◽  
Author(s):  
Milton S Love ◽  
Li Kui ◽  
Jeremy T Claisse
Keyword(s):  
Species Richness ◽  
Southern California ◽  
Oil And Gas ◽  
Fish Assemblages ◽  
Habitat Requirements ◽  
Rocky Reefs

Between 2005 and 2011, using manned research submersibles, we compared the fish assemblages associated with the midwater platform structures (at depths between 40 and 195 m) of two southern California oil and gas platforms, Gail and Eureka. Gail is a typical California platform, with rounded crossbeams and pilings, while the midwater jacket of Eureka, studded with bowl-shaped piling guides, is more complex. While the assemblages of both platforms were dominated by rockfishes (Sebastes spp.), there were also significant differences. Compared to Gail, Eureka: (1) exhibited higher densities of all species combined and of most species in common, (2) had more mature individuals of most species, (3) exhibited greater species richness, and (4) had higher densities of species typical of complex high relief. We propose that the complex midwater jacket of Eureka, with its many sheltering sites, resembles rugose natural rocky reefs. This research both reinforces the conclusion that many reef species have quite specific habitat requirements and that the platform decommissioning process must consider each platform individually.

scholarly journals Fish Assemblages Associated With Oil and Gas Platforms in the Gulf of Thailand

2021 ◽  
Vol 8 ◽  
Author(s):  
Euan S. Harvey ◽  
Stephanie L. Watts ◽  
Benjamin J. Saunders ◽  
Damon Driessen ◽  
Laura A. F. Fullwood ◽  
...  
Keyword(s):  
Coral Reef ◽  
Oil And Gas ◽  
Fish Assemblages ◽  
Economic Value ◽  
Offshore Structures ◽  
Economic Benefits ◽  
Gulf Of Thailand ◽  
Reference Sites ◽  
Remotely Operated Vehicle ◽  
Offshore Oil And Gas

Decommissioning of offshore oil and gas structures is either occurring, or imminent in most regions of the world. Most jurisdictions require that offshore structures be removed for onshore disposal. However, there is growing interest in understanding the ecological and socio-economic benefits of leaving structures in the water. Descriptions of how fish utilize the vertical structure created by wellhead platform jackets (platforms) will provide insights into possible outcomes of decommissioning alternatives, such as full removal, leave in situ, or translocation to a designated reefing site. We surveyed fish assemblages associated with seven platforms and five reference sites located ∼150 km offshore in the central Gulf of Thailand. The platforms spanned the entire water column (∼75 m) and were a mix of three and four legged structures. We used a Remotely Operated Vehicle (ROV) fitted with an underwater stereo video system to quantify the abundance, size, biomass, and economic value of fish associated with the platforms. We recorded 43 species of fish on the platforms and five reference sites with most fishes on platforms categorized as coral-reef or coral-reef-associated species. We observed a strong vertical zonation in the fish assemblage on the platforms. The Regal demoiselle (Neopomacentrus cyanomos) was numerically dominant (75% of all fish observed). We measured 3,933 kg of fish on the platforms with Caranx sexfasciatus accounting for 76.12% of that. We conservatively estimate each platform had a scaled mean biomass of ∼2,927 kg and the fished species had scaled mean economic value of 175,500 Thai Baht per platform. We estimated that the biomass of fish associated with the seven platforms was at least four times higher per unit area than some of the world’s most productive coral reefs.

A method of technical diagnostics for offshore structures

1994 ◽  
Vol 16 (2) ◽  
pp. 43-48
Author(s):  
Do Son
Keyword(s):  
Diagnostic Method ◽  
Joint Venture ◽  
Oil And Gas ◽  
Residual Life ◽  
Life Time ◽  
Offshore Structures ◽  
Technical Diagnostics ◽  
Offshore Platforms ◽  
South Vietnam ◽  
Local Destruction

This paper describes the results of measurements and analysis of the parameters, characterizing technical state of offshore platforms in Vietnam Sea. Based on decreasing in time material characteristics because of corrosion and local destruction assessment on residual life time of platforms is given and variants for its repair are recommended. The results allowed to confirm advantage of proposed technical diagnostic method in comparison with others and have been used for oil and gas platform of Joint Venture "Vietsovpetro" in South Vietnam.

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