As potential offshore oil fields shift from shallow water to deeper ocean, floating production, storage and offloading (FPSO) systems become more attractive than conventional huge fixed type platforms. Recently we have successfully completed conversion works of two FPSO's from old 280,000 DWT VLCC's and they will be towed and installed at Campos Basin, offshore Brazil. During this project elaborate hydrodynamic and structural analyses were performed to ensure proper function as an FPSO and to convince safety during conversion and towing stage. This paper summarizes general arrangement and typical results of the analyses. Introduction As potential offshore oil fields shift from shallow water to deeper ocean, floating type production platforms such as floating production. storage and offloading (FPSO) systems become more attractive than conventional huge fixed type platforms. The FPSO system is known as economical alternatives to fixed type platforms for deep water applications. Since FPSO has integrated function of production, storage and offloading, its conceptual design is very important to ensure the full performances or these multifunctions. Especially, mooring system has a unique device called turret. Turret enables the FPSO to weathervane with minimum environmental mooring force. A multi-path fluid swivel acts an essential role for oil transfer without leakage during weathervaning. In order to reduce operational cost mooring scheme without thruster-assistance is preferred in spite of quite deep water of around 1,000 meters. Recently Hyundai Heavy Industries has successfully completed conversion works of two FPSO's for Petrobras. Henrique Dias and Jose Bonifacio, from old 280.000 DWT VLCC's and they will be towed and installed at Campos Basin, offshore Brazil. During this project, elaborate Analyses1 were performed to ensure proper function as an FPSO and to convince safety during conversion and towing stage. It covers naval architectural calculations. stability. motion mooring, and fatigue analysis for in-place condition and/or towing condition. Also various global and local structural analyses were performed for floating construction, towing and in-place conditions. During the structural analysis, special attention was paid to consider highly corroded areas arisen from the previous usage as a VLCC. This paper summarizes general arrangement and typical results of the analyses for the Jose Bonifacio. General Arrangement Basically, the hull is converted from 280.000 DWT VLCC that is 17 years old. The general arrangement and principal particulars of FPSO are shown in Figure 1 and Table J respectively. It is claimed that the locations of a flare boom a turret and accommodations are important factors for general arrangement. Generally, the location of accommodation is arranged at stem part as it was for converted hull case. Therefore, the location of the flare boom is at bow which is far from accommodation to prevent the hazardous condition. in spite of forward direction against wind direction. Turret opening may be either at the midship or bow. To ensure the good weathervaning, bow is preferred in our case. However, midship may be chosen in cooperation with thruster-assisted mooring to improve the heave motion characteristics. On the forward part of main deck, a turret and a flare boom are installed.
Korean shipyards have been leading the construction of newbuilt offshore structures in the last 10 years. HHI (Hyundai Heavy Industries Co.) is one of major EPC contractors and has successfully built several FPSOs, drilling rigs and FPUs intended for worldwide operation. HHI has established a strong reputation in construction as the world leading shipbuilding yard and has highly experienced workforce. Numerous novel methods enhancing HHI's competitiveness were employed in its recent endeavors. They include new construction methods (Ground Build Method), work on new technologies in collaboration with external research entities and participation in JIPs; the recent one focused on nonlinear impact fluid forces due to slamming, green water and viscous roll damping.HHI is also well established in the area of hull design for offshore industry. It has recently designed fatigue free FPSO using FMS (Fatigue Methodology Specification) co-developed by EMDC and DNV.HHI can respond with high degree of flexibility to client's needs as it owns extensive facilities (several dry docks) and has mastered effective project management methods. This paper summarizes the recent successful offshore projects from the perspective of accomplishment through collaboration.
Tracheopathia osteoplastica(TO) is a rare, clinical and pathologic benign condition of unknown cause and characterized by submucosal cartilaginous or bony projections into tracheobroncheal lumen, usually not involved posterior membranous portion of tracheobroncheal tree. We report two cases of tracheopathia osteoplastica that involved trachea and both main bronchus, diagnosed by chest CT, fiberoptic bronchoscopic biopsy.
Hyundai Heavy Industries Co., Ltd. has developed a LNG-FPSO with production capacity of 2.5 MTPA to meet the demand of the offshore LNG well development in near future. This paper presents the experimental and the numerical study on the mooring and the offloading performances of the developed LNG-FPSO. In the FEED design stage, the turret mooring system and the offloading mooring system with side-by-side arrangement were designed using the quasi-dynamic method and verified through the model tests using the truncation method in the basin. It is known that the quasi-dynamic method is very efficient to calculate many environmental combinations for the evaluation of the turret mooring system and the offloading availability. And the numerical parameters for the truncated system are calibrated with the model test results with the same truncated set-up and it is expanded into the full depth model. In this study, it was verified that the safety of the station keeping system under the extreme environmental condition and the offloading performance satisfied the design requirement. Especially, the hydrodynamic and mechanical couplings between LNG-FPSO and LNG carrier were considered as the important parameters in the offloading availability with ship-to-ship arrangement. Finally, the design parameters such as the relative motion, line tension and fender load of offloading system were evaluated with considering the dynamic positioning system.
Deepwater floating systems consist of a vessel, risers, and mooring lines. To accurately simulate the floating systems in current, wind, and waves considering (1) bending and torsional stiffness of riser, (2) elongation of the mooring/riser elements, (3) complex end conditions, (4) internal flow effects, and (5) vortex induced vibration, it is necessary to evaluate the vessel motions and mooring/riser behaviors simultaneously in time domain. However, because the size of the system matrix increases significantly as the number of mooring/riser increases, it is quite time-consuming to solve all equations including both mooring/riser and vessel dynamics simultaneously. The present study was performed in order to develop a program for this problem. The 6DOF vessel dynamics is described by the Cummins equation. And the mooring and riser are modeled with the help of finite-element beam. The Newmark method is used as the time marching scheme of the FEM equations for each mooring/riser and the vessel. The coupled equations of the mooring/riser segments and vessel are solved alternatively at each time step. Mooring/riser and the vessel motion affect to each other in the way that the components of the forces at the segment ends are determined as functions of displacements and slopes of them. This procedure makes it possible to consider the coupling effects between vessel and mooring/riser efficiently. Also no iterations are required to match the vessel motion with the riser dynamics. This new approach allows us to use parallel computations and to deal with as many mooring/riser at the same time as necessary. The hydrodynamic forces induced by current are calculated by using the Morison’s formula. The VIV (Vortex Induced Vibration) effects are included in the way that the frequency and the shape of the riser vibration due to VIV are pre-calculated by iterations in the frequency domain. Then the finite element mooring/riser model is modified to consider the hydrodynamic loads including VIV and integrated in the final equations of the floating system in time domain.
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