Shallow water multiple prediction and attenuation, case study on data from the Arabian Gulf

2002 ◽  
Author(s):  
Riaz Alá'i ◽  
Dirk Jacob Verschuur ◽  
Jock Drummond ◽  
Stan Morris ◽  
Gerard Haughey
Keyword(s):  
Shallow Water ◽  
Arabian Gulf ◽  
Multiple Prediction

scholarly journals R-EPSI and Marchenko equation-based workflow for multiple suppression in the case of a shallow water layer and a complex overburden: a 2D case study in the Arabian Gulf

Geophysics ◽  
2020 ◽  
pp. 1-62
Author(s):  
Myrna Staring ◽  
Marcin Dukalski ◽  
Mikhail Belonosov ◽  
Rolf Baardman ◽  
Jewoo Yoo ◽  
...  
Keyword(s):  
Shallow Water ◽  
Adaptive Filters ◽  
A Priori ◽  
Arabian Gulf ◽  
Water Layer ◽  
Prediction Errors ◽  
Marchenko Equation ◽  
Sparse Inversion ◽  
Internal Multiples ◽  
Multiple Prediction

Suppression of surface-related and internal multiples is an outstanding challenge in seismic data processing. The former is particularly difficult in shallow water, whereas the latter is problematic for targets buried under complex, highly scattering overburdens. We propose a two-step, amplitude- and phase-preserving, inversion-based workflow, which addresses these problems. We apply Robust Estimation of Primaries by Sparse Inversion (R-EPSI) to suppress the surface-related multiples and solve for the source wavelet. A significant advantage of the inversion approach of the R-EPSI method is that it does not rely on an adaptive subtraction step that typically limits other de-multiple methods such as SRME. The resulting Green's function is used as input to a Marchenko equation-based approach to predict the complex interference pattern of all overburden-generated internal multiples at once, without a priori subsurface information. In theory, the interbed multiples can be predicted with correct amplitude and phase and, again, no adaptive filters are required. We illustrate this workflow by applying it on an Arabian Gulf field data example. It is crucial that all pre-processing steps are performed in an amplitude preserving way to restrict any impact on the accuracy of the multiple prediction. In practice, some minor inaccuracies in the processing flow may end up as prediction errors that need to be corrected for. Hence, we decided that the use of conservative adaptive filters is necessary to obtain the best results after interbed multiple removal. The obtained results show promising suppression of both surface-related and interbed multiples.

Relevance of an integrative approach for taxonomic revision in sponge taxa: case study of the shallow-water Atlanto-Mediterranean Hexadella species (Porifera:Ianthellidae:Verongida)

2012 ◽  
Vol 26 (3) ◽  
pp. 230 ◽  
Author(s):  
Julie Reveillaud ◽  
Céline Allewaert ◽  
Thierry Pérez ◽  
Jean Vacelet ◽  
Bernard Banaigs ◽  
...  
Keyword(s):  
Shallow Water ◽  
Phylogenetic Reconstruction ◽  
Taxonomic Revision ◽  
Integrative Approach ◽  
Cryptic Species Complex ◽  
Surface Network ◽  
Natural Toxicity ◽  
Shallow Water Species ◽  
Water Species

The identification of sponges that lack a mineral skeleton is always highly challenging, especially for Hexadella species, which are also fibreless. Recently, the yellow species Hexadella pruvoti Topsent was identified as a cryptic species complex while the pink coloured Hexadella racovitzai Topsent showed two highly divergent lineages. We performed a COI phylogenetic reconstruction using 27 new Mediterranean Hexadella samples in order to confirm the presence of divergent lineages within both shallow-water species. Specimens were described with an integrative approach combining morphological and cytological investigations, biochemical profiling and assessment of natural toxicity in order to identify diagnostic characters for each taxon. H. topsenti, sp. nov. is distinguished from H. racovitzai by its colour, its surface network shape, divergent secondary metabolite patterns and toxicity values. H. crypta, sp. nov. differs from H. pruvoti by a different encrusting growth form when alive, and by distinctively colouring the ethanol fixative solution. In addition, H. pruvoti and H. crypta show different types of cells with inclusions as well as distinct metabolic fingerprints. Natural toxicity values, however, do not permit the separation of H. pruvoti and H. crypta. Our work shows that only the use of a combination of complementary tools can provide relevant descriptions for some problematic taxa.

Simulation of impact of oil spill in the ocean – a case study of Arabian Gulf

2007 ◽  
Vol 146 (1-3) ◽  
pp. 191-201 ◽  
Author(s):  
Parikshit Verma ◽  
Satish R. Wate ◽  
Sukumar Devotta
Keyword(s):  
Oil Spill ◽  
Arabian Gulf

Installation of Long Span Boat Landing on Float Over Platforms - A Case Study

2021 ◽  
Author(s):  
Charles John George ◽  
Cibu Varghese ◽  
Faris Ragheb Kamal
Keyword(s):  
Production Process ◽  
Energy Absorption ◽  
Arabian Gulf ◽  
Offshore Platform ◽  
Offshore Platforms ◽  
Long Span ◽  
Heavy Lift

Abstract Fixed offshore platforms are normally provided with landing platforms that enable berthing of supply vessels, crew boats etc. These landing platforms or ‘Boat landings’ are energy absorption structures provided on substructures (jackets) of offshore platforms. Their purpose is to facilitate personnel access from vessel to platforms for performing various tasks including manning the platform, its maintenance etc. Vessel also approach the platforms for providing supplies in case of a manned platform and for providing bunkers, spares etc. As such, boat landing is an integral part of offshore platform and its design and installation becomes equally important. They are preferably located at leeward direction as far as practical, to avoid accidental vessel drift into the platform. For smaller standalone offshore platforms installed with Heavy Lift Crane Vessels, boat landing is installed after the jacket is piled to seabed. Since sequence of installation of boat landing is prior to that of Topside, such installations are straightforward and without obstructions from the Topside. For the bigger accommodation, production, process platforms located in super-complex (or standalone) with topsides installed by float over method, boat landings sometimes are in the wide float over barge slots. In such cases, installation of boat landing becomes very critical due to the post installation after the Topside and associated obstructions from the Topside. This is similar or more critical than a boat landing removal / refurbishment activity carried for a brownfield project. This paper explores the challenges and associated steps adopted to execute the safe installation of these critical structures underneath a newly installed Topside. This case study details the installation of ∼300mt boat landings onto recently installed Greenfield platforms in Arabian Gulf using efficient rigging, suiting the EPC Contractors’ crane assets.

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