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Practical and Theoretical Assessments of Subsea Installation Capacity for HYSY 201 Laybarge According to Recent Project Performances in South China Sea
Wang, Facheng (COTEC Offshore Engineering Solutions) | Luo, Yong (COTEC Offshore Engineering Solutions) | Xie, Yi (COTEC Offshore Engineering Solutions) | Li, Bin (China Offshore Oil Engineering Co., Ltd) | Li, Jiannan (China Offshore Oil Engineering Co., Ltd)
Abstract As the first deep-water pipe-lay vessel in China, the recently launched Hai Yang Shi You (HYSY) 201 has been designed for up to 3, 000m water depth pipelay and other deepwater subsea equipment installation activities, with its advanced Dynamic Positioning (DP) 2/3 and 4, 000 tons lifting capacity. After the appearances in several projects in South China Sea (SCS), where water depths ranging from 300m to 1400m, the performance of HYSY 201 has been observed. The excellent project experience has been shared from four perspectives of pipe-lay, lifting, DP system and remote field development requiring multi-function constructions respectively. The performance of integrated pipe-lay and lifting acitivites in one project highlights the economic advantages of the vessel in remote filed developments. The as-built survey results have been employed to provide a quantitative investigation on the final project deliverables by HYSY 201. The theoretical evaluation of the subsea installation capacity limitation has been carried out by considering both the recorded practical operation data and equipments equipped by the vessel. Based on the analysis and study results, together from the field experience, the limitations of subsea installation capacity have been suggested for HYSY 201.
- Asia > China (0.83)
- North America > United States > Texas (0.29)
- Facilities Design, Construction and Operation > Processing Systems and Design > Process simulation (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems (1.00)
Liuhua 11-1 FPS Dry-dock Upgrade and Life Extension - Motion Analysis and Weather Window Selection for Towing
Luo, Yong (COTEC inc) | Huang, Shu Guang (China Offshore Oil Engineering Co., Ltd) | Zhang, Guang Lei (Offshore Oil Engineering CO.,Ltd) | Yang, Liang (Offshore Oil Engineering CO.,Ltd) | Yang, Hui (China Offshore Oil Engineering Co., Ltd)
Abstract The Liuhua 11โ1 FPS is a major component of the Liuhua 11โ1 Development System, which is located about 200km southeast of Hong Kong in the South China Sea. For upgrade and life extension purpose, the FPS was disconnected from field in early November, 2011, and was towed to Guang Zhou Huangpu Shippbuilding Co., China, for dry-dock upgrade modification. And the upgraded FPS was wet towed back and reconnected at the field in May, 2012. The towing motion performance of โNanhai TiaoZhanโ semi-submersible platform was analyzed by using SESAM program, which is based on Morison's equation and 3D potential theory. According to the design maximum allowable roll or pitch amplitude of 6 degrees, the maximum allowable significant wave heights were calculated for a range of wave period based on a cyclic iterative method. Then suitable weather widow for the towing operation was recommended under the consideration of limited sea states, climate characteristic of South China Sea and the updating project schedule. Introduction The LH 11โ1 oil field is located about 200km southeast of Hong Kong in the South China Sea in approximately 310m depth of water. LH 11โ1 FPS, which named โNanhai TiaoZhanโ, is a major component of LH 11โ1 oil field development. The FPS was a modified drilling semi-submersible converted from a Sedco 700 series drilling rig built in 1975 and in 1995, it was converted again to a floating production unit in Singapore and then deployed at LH 11โ1 oil field, permanently moored by 11 mooring legs. The Unit is classed by American Bureau of Shipping (ABS). It was originally designed for a service life of 10 years (from 1995) and has been continuously operating for more than 15 years. At the same time, a new oil field Liuhua 4โ1 (OTC-24042), about 11 km away northwest LH 11โ1, was in development planning with the utilization of LH 11โ1 FPS facilities through a subsea tieback. Therefore, additional topsides capacities and the life extension of this aged semi-submersible FPS became necessary. CNOOC Ltd, Shenzhen is the owner of this LH 11โ1 FPS. COOEC was selected as the contractor for the engineering and construction support of this FPS dry-docking upgrading and life extension project. CSSC Guanzhou Huangpu Shipbuilding Co., Ltd was contracted by the owner as the dry-docking shipyard for the upgrading construction. Because the environmental conditions of South China Sea are complexity and capricious, motion analysis and appropriate weather window selections for the disconnection, voyage and field reconnection operations became the key issues for making the whole project schedule. In this paper, the motion performance of the FPS during towing was analyzed by using 3D potential theory. SESAM program developed by DNV was used in the analysis. By using a cyclic iterative method in a frequency analysis to perform short term statics, limited sea conditions, which satisfied the maximum allowable roll and pitch amplitude not exceed 6 degrees, were obtained. Then a whole update modification project schedule was recommended according to the weather window selection of towing.
- Asia > China > Hong Kong (0.45)
- Asia > China > South China Sea (0.34)
- North America > United States > Texas (0.30)
- Asia > China > Guangdong Province > Shenzhen (0.25)
- Transportation > Marine (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > Asia Government > China Government (0.76)
Liuhua 11-1 FPS Dry-dock Upgrade and Life Extension - Mooring System Evaluation and Optimization
Zhong, Wen Jun (China Offshore Oil Engineering CO.,Ltd) | Liu, Bo (China Offshore Oil Engineering Co., Ltd) | Luo, Yong (COTEC Inc) | Yang, Hui (China Offshore Oil Engineering CO.,Ltd) | Yin, Han Jun (China Offshore Oil Engineering Co., Ltd)
Abstract The evaluation of existing mooring system and the development of an appropriate optimization design became the key issues in the Liuhua 11โ1 FPS dry-dock updating project because this optimized mooring system has to face new challenges, such as the update of site metocean conditions, the revision of wind force coefficients due to upgraded topsides, and the additional corrosion allowance for chain links due to extra 15-year service life extension compared with the original system design. A design team was formed to give the evaluation of the existing mooring system based on mooring line tensions and offset limits according to the latest industry standard for a permanent mooring system. Since the existing mooring system marginally failed the design requirements based on the evaluation, system optimization design focused on the adjustment of mooring line pretensions has been carried out to improve the mooring system performance and eventually to satisfy the classification requirements for the tension safety factors and the platform offset limits driven by the riser designs. The mooring system analysis was conducted in time domain. The Ariane program developed by BV was used in the detailed mooring system analyses. For the calibration and verification purpose, the system evaluation and the optimization design had also been independently verified with DNV's DeepC program. Introduction The LH 11โ1 oil field is located about 200km southeast of Hong Kong in the South China Sea in approximately 310m depth of water. LH 11โ1 FPS, which named โNanhai TiaoZhanโ, is a major component of LH 11โ1 oil field development. The FPS was a modified drilling semi-submersible converted from a Sedco 700 series drilling rig built in 1975 and in 1995, it was converted again to a floating production unit in Singapore and then deployed at LH 11โ1 oil field, permanently moored by 11 mooring legs. The Unit is classed by American Bureau of Shipping (ABS). It was originally designed for a service life of 10 years (from 1995) and has been continuously operating for more than 15 years. At the same time, a new oil field Liuhua 4โ1 (OTC-24042), about 11 km away northwest LH 11โ1, was in development planning with the utilization of LH 11โ1 FPS facilities through a subsea tieback. Therefore, additional topsides capacities and the life extension of this aged semi-submersible FPS became necessary. CNOOC Ltd, Shenzhen is the owner of this LH 11โ1 FPS. COOEC was selected as the contractor for the engineering and construction support of this FPS dry-docking upgrading and life extension project. CSSC Guanzhou Huangpu Shipbuilding Co., Ltd was contracted by the owner as the dry-docking shipyard for the upgrading construction.
- Asia > China > South China Sea (0.34)
- North America > United States > Texas (0.29)
- Asia > China > Guangdong Province > Shenzhen (0.24)
- Asia > China > Hong Kong (0.24)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > Asia Government > China Government (0.75)
Abstract Dry completion by means of a surface wellhead platform is a viable alternative to subsea wet completion in all water depths. Dry completion offers the benefits of better reservoir testing and monitoring, drilling and workover capabilities, lower operating costs due to ease of well intervention, better flow assurance, and increased recovery of oil and gas. This paper evaluates a variety of dry tree platform concepts, including both the established Spar and TLP and several newly developed platform concepts, for application in the Gulf of Mexico, offshore West Africa and Brazil. A single column medium draft floater, three and four column extended base TLPs are the new concepts that are included in this paper. A wide range of payloads is considered. Main particulars, global performance characteristics, advantages, and limitations and cost saving features of the new concepts are presented. Using the results from a screening study, trends in the global response, weights and costs are presented and discussed. A map of application domains for the dry tree platform concept is presented on the basis of cost comparisons. Introduction When oil companies develop a reservoir in deep water, a floating platform with the dry wellheads is often determined to be more economical than subsea wells. The optimum platform, however, will depend on many factors specific to the field development, such as geographic location, local wind, waves and current, water depth, number of wells, facility payload, environmental issues, etc. To implement the surface tree option, the relative motion between the production riser and the platform needs to be within certain allowable limits. This requirement limits the allowable platform vertical motion. Only two deepwater dry tree platform concepts are field proven: The conventional Tension Leg Platform (TLP) and the Conventional Spar. A comparison of TLP and Spar weight and cost efficiencies with regard to variations in payload and water depth is provided in Reference 1. However, engineering innovation never stops. In recent years, a variety of new, innovative, dry tree platform concepts have been proposed. The new concepts are aimed at reducing the cost of dry completions in deepwater. Three of the innovative new concepts are included in the comparative evaluation presented in this paper. These are:Single-Column Floater (SCF) Extended-Base 4-Column TLP (ETLP-4) Extended-Base 3-Column TLP (ETLP-3) In addition, we include some comparisons with the proven conventional TLP and Conventional Spar concepts and the emerging Truss-Spar concept. Main objectives of this paper are to review and compare these dry tree platform concepts and to illustrate the trends of payload and cost efficiencies. The findings generate insightful knowledge for future concept selection in GOM, West Africa, and Offshore Brazil. Review of Design Environments The severity of design environment depends on the location of application. A summary of some of the main environmental design criteria for deepwater GOM, West Africa, and Brazil is provided in Table 1.
- North America > Mexico (0.69)
- Africa > West Africa (0.69)
- South America > Brazil (0.67)
- North America > United States > Texas (0.28)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Ewing Bank > Block 965 > Morpeth Field (0.89)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Ewing Bank > Block 964 > Morpeth Field (0.89)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Ewing Bank > Block 921 > Morpeth Field (0.89)
- (6 more...)
ABSTRACT This paper describes statistical techniques for analyzing failure probabilities of long mooring lines. The long line is treated as a series of segments, each as long as the break or fatigue test specimens. Termination failure statistics are treated separately. The analysis techniques are applicable to mooring lines comprised of chain, Wire, or fiber rope. They are also appropriate for long electrical and control cables, hoses, and umbilicals. Examples are given to illustrate the techniques. INTRODUCTION There is much interest in assessing the reliability of deepwater mooring systems.! Mooring lines are typically much longer than the short test specimens used in determining breakmg strength and fatigue life statistics. For example, each ofseveral mooring lines used on a floating platform in deep water might be over 1000 m (3000 ft) long, but the specimens used m break and fatigue testing might only be 10 m (30 ft) long., This paper addresses problems in relating break and fatigue test .data obtained from tests on short specimens to the reliability of the same type of line in very long lengths. It includes the effects of terminations with different statisticalproperties than the body of the line. . "A chain is. only as strong as it's weakest link". For simplicity chain will be used as a model in this paper. The technique s also apply to wire and fiber ropes, in which performance IS determined from tests on short specimens and the ropes used in service are much longer. "Short rope" can be substituted for 'link', and long rope" can be substituted for 'chain' throughout this paper. Here the word termination means any component or method used to connect parts of the mooring line together or to connect the entire mooring line to a vessel or an anchor. Examples include chain connector links shackles and splices in wire or fiber rope. " The probability of failure at any given load increases as the total line length and the number of terminations increase. Of course. It also depends on the mean strength and the strength variability of these components. If sufficient statistical data for the components are available, the analysis techniques described m this paper can be used to design a system with an acceptable risk of failure. The prediction of reliability for a length of chain based on the statistics of individual links is first considered. The effects of terminations on the reliability of this length of chain areintroduced later. STATISTICAL CONCEPTS The Chain Link Model A theoretical chain comprised of individual links is shown in Figure la. It is analogous to a long length of chain made upof shorter lengths equivalent to the test specimen length, as shown in Figure lb. It is also analogous to a long length of rope, again made up of shorter lengths equivalent to the test" specimen length, as shown in Figure lc. The breaking strength of the long chain can be determined from the strengths of individual links.
ABSTRACT: The paper deals with the motion simulation of lifeboats launched from fixed or floating platforms and its application to collision risk assessment. The mathematical model of the Davit launch system is presented. By solving the motion differential equations, the three dimensional motion responses of the lifeboat and the platform are simulated in the time domain and the clearance between the lifeboat and platform structural members are monitored. Numerical examples are given and key parametric effects are investigated through deterministic and probabilistic analyses. It is demonstrated that the motion simulation combined with probabilistic analysis techniques can provide an effective tool for quantitative risk assessment of offshore emergency evacuations using lifeboats. 1. INTRODUCTION During an emergency evacuation from offshore fixed or floating platforms, it is of vital importance that lifeboats can be successfully launched and disconnected from the platform. This is actually one of the recommendations made in Cullen's Report [1] into the Piper Alpha disaster which states: "Operators should be required by regulation to submit to the regulatory body for its acceptance an evacuation, escape and rescue analysis in respect of each of its installations". Aimed at improving the understanding of thebehaviour of lifeboats during launch and assessing the risk involved due to possible collisions with platform structural members, the lifeboat launch operation is studied using response simulation techniques. The current study focuses on the traditional Davit launch of lifeboat system for TEMPSC (Totally Enclosed Motor Propelled Survival Craft) whereby the lifeboats are lowered vertically from winches on two cables (see Fig.1). It addressee the following main issues:Motion responses of lifeboats during descending from floating or fixed platforms Lifeboat movements during turning and sailaway Key parameters and their effects on motionand risk of collision Probabilistic analysis as a tool for safetyassessment For lifeboats launched from floating structures Such as semisubmersible units, the lifeboat motion response caused by environmental loading and the platform motion is mathematically modelled. The motion equations are solved numerically to simulate the lifeboat and platform responses and monitor the occurrence of collision in the time domain. Impact velocity can be computed if collision occurs to determine the extent of damage. Investigations of key parametric effects are carried out. The main parameters studied are the types of platforms, severity of environment, vertical descent speed, disconnection time and lifeboat heading. Useful results are obtained which will help the development of appropriate evacuation procedures. It is also demonstrated in the paper thatprobabilistic techniques can be incorporated into the analysis to obtain a quantitative indicator of the risk level of lifeboat launch. The results canbe valuable for aseessing the adequacy of evacuation procedures using lifeboats.
- Health, Safety, Environment & Sustainability > HSSE & Social Responsibility Management > Contingency planning and emergency response (1.00)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems (1.00)
- Management > Risk Management and Decision-Making > Risk, uncertainty, and risk assessment (0.88)
- (2 more...)