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Abstract The combination of decreasing ice volume and thickness in Arctic regions results in extended activities of the oil and gas companies in these areas. Actually installed offshore structures are mostly fixed or moored ones. Problematic for moored structures especially with a turret position leading to an indifferent encounter angle is the heading of the vessel regarding the ice drift direction. That is why the idea was raised to combine moored offshore structures (such as FPSO's) with a dynamic heading control system. By such a system the heading can be adjusted to the optimal encounter angle of either waves or ice. Thereby the resistances especially due to changes of the ice drift direction shall be significantly reduced. The advantage of this system in comparison to a completely DP controlled vessel is, that the ice loads are mainly taken by the passive mooring system which does not need any fuel and is able to handle with high resistances while only the heading is controlled by the active thrusters. In case thrusters are installed at the front of the vessel which faces the ice, they may help to protect the turret, mooring lines and risers by their wash from ice contact. Additionally the vessel may operate independently in case of an emergency release of the turret due to critical ice loads on the mooring system. To investigate the benefits and challenges of moored and heading controlled vessel a new test set-up for ice model tests was developed at HSVA. The test set-up combines the already existing knowledge for moored structures with the recently developed DP system for model tests in ice. The DP system is a result of the recent research project DYPIC () and is operating in a new designed mode which only controls the heading of the vessel. During testing the mooring system is simulated by lines leading from the turret to an underwater framework. The mooring characteristic (stiffness) is simulated by an individual combination of springs submerged and fixed on the framework. Above the water surface the model is tracked by an optical tracking system which is connected to the modified DP system. The optical tracking system and the submerged framework are fixed to the carriage. The ice drift is simulated by the movement of the towing carriage. The paper will describe the test set-up possibilities for the new test method as well as the experiences with the first ice model tests. Especially the challenges according to the modified dynamic heading algorithm shall be discussed. Based on analysis of the ice model test results the future work on the algorithm with regard to full scale vessels will be pointed out.
MTD Ltd started life, in 1977, as a directorate - The Marine Technology Directorate - of the Science and Engineering Research Council (SERC) Nine years later, in line with its normal policy, SERC relinquished sole responsibility for continuation of the directorate. MTD Ltd is now a company limited by guarantee whose running costs are provided jointly by SERC, government departments (DEn, DTI and MOD) and industry (largely from the oil and gas sector). SERC still identifies research funding, currently about £3 5m/year, for allocation through MTD Ltd to UK universities and polytechnics, MTD Ltd acts as SERC's agent in this respect for research in marine technology Funding for the research, especially in the earlier years, has been provided mostly by SERC, however MTD Ltd was established in the first instance with the major aim of serving the marine industry, and that industry has become increasingly involved, initially by advising on priorities for research and latterly also by providing a significant proportion of the research funds and by monitoring or actually collaborating in the work Formal methods for co-funding and collaboration are:club funded (multi-project, multi-sponsor, multi-contractor), in these programmes about half of the research costs come from SERC, the balance from a group of industrial and government sponsors , the distribution of funding may be similar to that for a managed programme but on occasions is shared equally between all the sponsors including SERC, cooperative projects (normally only one other sponsor apart from SWC); costs are shared equally between SERC and the industrial partner who also is expected to collaborate in undertaking some parts of the research. In return for this substantial involvement the IPR for any development arising from the project is assigned to the industrial partner on the basis of a revenue-sharing arrangement with the academic institution In addition to these collaborative arrangements a proportion of research supported through UTD Ltd is funded wholly by SERC. With these funding arrangements, that is, with the preponderance of SERC funding, it is not surprising that the timescales envisaged for exploitation of the research are medium to long term, not short term However, before describing more fully the research in automation technology it is worth noting an important recent development which will extend the range of activities of MTD Ltd In July of this year UEG Offshore Research was acquired by MTD Ltd from CIRIA UEG was well known for its information services to the industry and for its promotion and management of joint industry projects with an output of immediate use to engineers MTD Ltd will continue and expand these activities, thus adding projects with a shorter return period to the spectrum of research that is has previously supported RESEARCH INTO AUTOMATION TECHNOLOGY MTD Ltd's research is organised, somewhat arbitrarily, into five major areas - mineral resources, physical ocean environment, ocean structures and materials, ships and floating structures, and underwater working.
From Model to Reality: Practical Insights from Mooring Integrity Monitoring Using Vessel Position Data
Jayasinghe, Kanishka Milinda (AMOG Consulting) | Thomas, Clare Victoria (AMOG Consulting) | Kilner, Andrew Allan (AMOG Consulting Inc.) | Eassom, Adrian Conrad (AMOG Consulting) | Gumley, Jonathan Matthew (AMOG Consulting)
Safe and reliable access to offshore energy, whether it be through hydrocarbon or renewable sources, requires offshore infrastructure held on station by well designed, well installed and well monitored mooring systems. The bounds of what is possible with mooring integrity monitoring technology has expanded in recent years, providing stakeholders with a more complete view of risk over the life of the floating facility. As regulatory requirements eventually follow from these innovations, there is also increasing pressure on operators to expand their monitoring capabilities to retain compliance. This paper presents an overview of some of the insights gained from using Global Navigation Satellite System (GNSS) vessel position data and metocean data for real-time mooring integrity monitoring. The means through which a GNSS-based integrity monitoring system can be programmed to detect mooring failures is presented and compared with alternative monitoring techniques. The potential for such a GNSSbased system to complement or replace other methods such as in-line load cell is discussed, particularly in scenarios where the installation or replacement of such direct mooring line monitoring technologies can be prohibitive from an operational or cost perspective. The practical considerations gathered from seven combined years of operational mooring integrity on various offshore facilities are also discussed, including the use of metocean monitoring and forecasts, data rate, resolution, accuracy, delay and quality considerations, and the challenges involved in rolling out such a system on an operating facility. This paper provides operators of floating facilities with insights into the kind of data which should be considered for an effective monitoring solution, as well as an approach to combine different data streams (vessel offsets, first order motions and environmental data) to derive a holistic assessment of mooring integrity. This information can be valuable for operators defining the scope of monitoring for new facilities or looking to get the most value out of the data on their existing facilities, where a system such as the one presented can provide a quantitative basis for operational decisions and improve the regulatory and risk compliance of offshore facilities. 2 OTC-31866-MS
Abstract Super duplex stainless steel (SDSS) tube is a main component in steel tube umbilicals to convey hydraulic fluids, chemicals or to control the flow of gas into subsea wells. Butt welds are used in the umbilical tube manufacturing for all tube joints and their quality directly impacts the in service performance of the steel tube umbilical. The butt welds are 100% inspected by X-Ray radiography. The obtained images are 2D shadowgraphs of a 3D object and, as such, they are limited in providing the exact depth of the defects inside the weld and part of geometry information of the weld is easily lost. To address this radiography limitation, the acceptance criteria of NDT are therefore very strict, and generally no porosity is allowed within the butt welds. As result, high rejection rate can be observed for thick wall tube (WT > 2.5mm). This limitation can be overcome by replacing X-ray radiography with X-ray Computed Tomography (CT). This technique provides a full 3D picture of the butt weld and allows enhancing the weld quality and improves productivity by reducing rejection rate caused by lack of information on the flaw depth through the wall. The technology can constitute a step change in the Non Destructive Testing (NDT) technology for the production of umbilical tubes. This paper presents the results of the X-ray CT inspection of umbilical tube butt weld and the concept design of a computed tomography machine for on line butt weld inspection. The machine is based on a computer controlled rotating gantry on which an X-ray source and a digital detector are installed. This gantry can perform a 190° rotation, during which several hundred radiographic projections of the inspected weld can be acquired under different view angles. A purpose developed image reconstruction software processes the acquired data to provide the full 3D representation of the weld. The article describes the selected X-ray chain, the reconstruction algorithm and the effect of the reduction of the number of acquired projections on the resolution of the 3D image of the weld. The study demonstrates that CT is a very pertinent technique for the inspection of butt welds in an industrial production environment, with superior accuracy compared to film or digital radiography. The combination of a dedicated CT machine and state of the art reconstruction algorithm can provide volume information of the weld flaw, for example gas pores, as small as 5 % of the tube's nominal wall thickness (150 ^m for a 2.7 mm WT tube), showing the ease of interpretation of CT images with respect to classical radiographies.
- Health & Medicine (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Ant Colony Optimization For the Seismic Nonlinear Inversion
Chen, Shuangquan (CNPC Key Lab in Geophysics, China Petroleum of University, Beijing) | Wang, Shangxu (CNPC Key Lab in Geophysics, China Petroleum of University, Beijing) | Zhang, Yonggang (Science and Technology Development Department, SINOPEC, China)
ABSTRACT In the complicity seismic inversion, the solving method is getting an best result from a non-linear restriction. With analysis the principle of the ant colony optimization algorithm, an improved ant colony optimization in solving seismic non-linear inversion problem is proposed in this paper. The algorithm integrates the forward feedback, distributing compute method and greedy enlighten searching method. And it is a good algorithm to the seismic inversion. The new algorithm is explained in details and some model simulations show the algorithm is very effective in finding global optimizations.
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Data Science & Engineering Analytics > Information Management and Systems > Artificial intelligence (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic modeling (0.90)