Topside Module Research Articles

Design and numerical simulation of the elastomeric support for the topside modules of an FPSO

Elastomeric support utilizing steel-reinforced elastomeric bearing pads (SREBPs) has been applied to offshore structures gradually. This study presented a process for designing the offshore elastomeric support. And a specific numerical method was introduced to synchronously simulate the hydrodynamic responses and structural interactions between hull and topside modules of a spread-moored floating production storage and offloading (FPSO) unit with elastomeric-supporting topside modules. Furthermore, a model test of the target FPSO was conducted in a deepwater offshore basin to validate the numerical simulation, and the numerical results were consistent with the experimental outcomes overall. The numerical results demonstrated that both bearing force and stress of the SREBPs fell within the design scope, and the maximum bearing force on vertical SREBPs was found to be around 1.3 times the weight of a corresponding topside module, considering the dynamic effects resulted from motion responses of the FPSO. Additionally, the maximum bearing force acting on anti-uplift SREBPs can refer to the peak value of a vertical SREBP's dynamic force correspondingly. The horizontal interactions between hull and topsides mainly depend on inclination of the hull, so the bearing forces of horizontal SREBPs are closely related to the severity of rolling and pitching.

Coupled response analysis of dual lifting vessels during collaborative lifting topside module

Offshore assembly and disassembly operations represent a multi-billion-dollar market potential. Collaborative lifting by multiple vessels has emerged as a new operating paradigm for integrated offshore facilities assembly and disassembly. Hence, this paper investigates the hydro-dynamic interaction of dual lifting vessels in collaborative lifting operations. The coupled motions during multi-body operations are simulated using the commercial software SESAM. The feasibility of the numerical model for coupled motions in collaborative lifting is verified by comparing the numerical results of topside motions, vessel motions, and vertical lifting arm loads against experimental measurements. The effects of wave heading and period on the hydrodynamic responses of the topside module, dual lifting vessels, and lifting arms during collaborative operations are studied. Their influence patterns and mechanisms are analysed in detail. The results show that transverse waves and head wave induce significant heave and pitch motions of the topside module and vessels, but the maximum vertical loads on the lifting arms occur in oblique waves. The motion responses of the topside module and vessels increase with longer wave periods under the oblique sea condition, and roll motions are more sensitive to large periods compared to the gradual rise in heave and pitch.

Study of the wet-towing transportation of an FPSO with elastomeric-supporting topside modules

This study focuses on the wet-towing transportation of an FPSO with elastomeric-supporting topside modules. In the study, an approximation method is utilized to calculate the wet-towing resistance in the design sea state for determining the wet-towing configuration. Meanwhile, the study successfully achieves to simulate the hydrodynamic responses and structural interactions synchronously for the complex wet-towing system. This numerical method is applied to the feasibility analysis of the wet-towing configuration in the design sea state, which indicates that the mean wet-towing resistance, peak towline tension, and dynamic responses of the FPSO are all within the design scope, proving that the wet-towing configuration is feasible. A parameter sensitivity analysis is performed for the wet-towing transportation, which reveals that the increase in towing speed and severity of sea state results in larger towing resistance. Extending the towline length has a significant dampening effect on both peak towline tension and its fluctuation during extreme sea state. The excursions of wind, wave, and current incident directions from the towing route can lead to the offsets of the FPSO, so an auxiliary tug is necessary to keep the FPSO in the planned route, and the wet tow in head sea is recommended.

Structural Integrity of Welded Joints: An Investigation of the FPSO Module Stools

The main goal of the present work is the investigation of a construction and integration of topside modules for an FPSO in Brazil. Most of the topside module structure manufacturing was subcontracted to a third-party company in Europe. During assembling work undergoing at the construction site, several structural details nonconformities were reported by the EPC Group quality control team, e.g., misalignment of stiffeners at the diamond plate and stool connections, geometry irregularities, and unexpected thickness changes on the connection of diamond plates with the correspondent I beam flanges of the pancakes, unexpected bevel buttering to correct joint imperfections which presented several weld flaws in it. Topside structures are subjected to cyclic loading during operation, hence, subjected to fatigue loading. The latter is of concern since the structural integrity of the welded joints must be met for the entire life of the FPSO. The EPC Group required an independent appraisal of the welded joints and structural details nonconformities. They also requested an Engineering Critical Assessment (ECA) on critical joints to be carried out to determine if there might be any flaws compromising the structural integrity of the topsides. Finally, ECA recommended mitigation actions, which could contribute to new topside module integrations for FPSO in Brazil.

Optimal design of FPSO topside module for in-place, lift and weighing conditions utilizing meta-heuristic optimization algorithms

Optimal design of FPSO topside module for in-place, lift and weighing conditions utilizing meta-heuristic optimization algorithms

Application and analysis of elastomeric supporting style for topside modules of a spread mooring FPSO

The offshore elastomeric supporting style via steel reinforced elastomeric bearing pads (SREBPs) has been in use gradually. In this study, the elastomeric supporting style used for the interfaces between topsides and stools is adopted by a spread mooring FPSO to analyze the responses of SREBPs and evaluate the applicability. Firstly, the motion responses of target FPSO are numerically simulated to check if the mooring system is safe. Then, the hydrodynamic responses are taken as the boundary conditions of hull for the multibody dynamic simulations. In the simulation, a compression spring model is proposed to equivalently replace the SREBPs. The stiffness of equivalent compression springs is obtained by linear fitting of the stiffness data from finite element analysis of SREBPs. Finally, the multibody numerical results show that the SREBPs can reach into yield state, but if there are assistant devices helping to limit the deformations, the SREBPs would work well. The largest deformations of SREBPs are observed to be sensitive to the hydrodynamic responses, so the SREBPs can still reach into yield state in extreme case. In that condition, it is recommended to bond the topsides to the stools and the numerical results confirm that it is available.

Calculation and analysis of sea-fastening support and welding strength of topside module

Marine structures are usually built on land as a whole modular, using barges to transport to the designated area for installation. This paper presents the sea-fastening design methodology and results of the topside module which is to be transported by self-propelled barge. The combination of its self-weight, wind load and barge acceleration in waves will act on the topside module and barge in the process of marine transportation, this paper mainly analyzes and calculates the temporary support frame and the grillage members of the topside module by SACS software. Then the top plates and the base plates transmit the member end forces of sea-fastening grillage members taken from SACS output, in order to ensure the strength, the bracket plates are welded to the grillage columns, braces and the bottom of temporary support frame. The strength of all fillet welds shall be checked.

20 YEARS DECOMMISSIONING EXPERIENCE - EVOLUTION OF INNOVATIVE SOLUTIONS

Decommissioning is an increasing market sector which has been gradually gathering momentum particularly in the North Sea. The forecast expenditure for removing existing platforms increases with time. This comes together with the increasing complexity of the decommissioning operation. Experience and expertise in this field are key for success. Saipem have been contracted to perform a number of ‘removals’ ranging from subsea templates, subsea pipelines, seabed debris clearance, jacket structures and topside modules. This paper provides an account of our experience gained over the last 20 years performing decommissioning activities. The paper presents the evolution of the techniques developed and focuses in particular on the Lift and Tow method developed after 2004 for a number of subsea applications. Problems always materialise post contract award due to inadequate data. The paper gives a detailed description of the Lift and Tow method along with various innovative techniques developed for this method, ranging from lifting operations supported by motion forecasting through to personnel access onto the structures.

Root Cause Analysis of Project Delay in BGC-TEG Project

PT WEI is a company that the main business as fabricator contractor for oil and gas and renewable energy industry located at Batam, Indonesia, they have operate for more than 15 years. The company produce types of facilities such as Process Packages module, FPSO (Floating Production Storage and Offloading) Topside Modules, E-house module and Sub-Station packages for client from all over world. The problem on this research is the delivery delay issue during execution of the BGC-TEG project. the project that have scope of EPC (Engineering Procurement and Construction) contract for delivery process module include mechanical equipment, piping and accessories for client at middle east, the delivery project delay is 21 months from original contract 11 months. The research to determine main factor that contribute to the delay by quantitative method, to gain information and identify alternative for improvement action. The primary data gathered from interview with some person in charge team member of the project. The secondary data gain from internal company document, project record and report, and project repository data base. Study literature of some similar case of project delay from various papers and articles reviewed. Fishbone diagram as analysis method with framework based on PMBOK by Project Management Institute to gain the root cause factors and propose solution alternative action to prevent same issue happen on future.

Dropped Object Impact Analysis Considering Frequency and Consequence for LNG-FPSO Topside Module

Recently, quantitative risk assessment (QRA) has been widely used as a decision-making tool in the offshore industry. This study focused on analyzing dropped objects in the design of a modern offshore platform. A modified QRA procedure was developed for assessing production module protection against accidental external loads. Frequency and consequence analyses were performed using the developed QRA procedure. An exceedance curve was plotted, and a high-risk management item was derived through this process. In particular, simulations and experiments were used to verify the difference between the potential and impact energies according to drop orientation. When the object dropped in a specific orientation, the impact energy was confirmed to be up to 4.7 times greater than the potential energy. To reflect the QRA results in structural design, the proposed procedure should be used to calculate the maximum impact energy. The proposed procedure provides a step-by-step guide to assess the damage capacity of a production area as well as the damage frequency and consequences.

Improvement of Fatigue Life with Local Reinforcement for Offshore Topside Module during Marine Transportation

Improvement of Fatigue Life with Local Reinforcement for Offshore Topside Module during Marine Transportation

Passive fire protection design of a FPSO topside module structure using CFD and nonlinear structural analysis

Passive fire protection design of a FPSO topside module structure using CFD and nonlinear structural analysis

Structural Safety Evaluation for the Hydraulic Power Unit of Topside Module According to the Movement of Offshore Plant

Structural Safety Evaluation for the Hydraulic Power Unit of Topside Module According to the Movement of Offshore Plant

Study on the Structural Behaviour of the Topside Modules of FPSO under the Forces Exerted on the Ship Hull

Study on the Structural Behaviour of the Topside Modules of FPSO under the Forces Exerted on the Ship Hull

Optimal Layout Design of a Liquefied Natural Gas FPSO: A Case Study

Abstract An liquefied natural gas (LNG) FPSO is a floating, production, storage, and offloading facility with a LNG plant, including all ancillary facilities. In contrast to commercial vessels, the various parts of the process are located topside and are distributed as modules that are installed on the deck. The design of an LNG FPSO requires many considerations such as international codes and standards, the owner's requirements, and the operation and maintenance philosophy. To resolve the many considerations in FPSO design, we proposed an optimization method for the topside arrangement in the previous study. Based on the previous study, an integrated optimization technique for an LNG FPSO is proposed to obtain the optimal principle dimensions, the arrangement of the hull tanks, and the layout of the topside modules and equipment that satisfies many requirements for not only the topside but also the hull. As a case study, the topside and hull layout of an LNG FPSO is optimized in terms of safety, economics, and stability. The case study shows that the proposed method can develop the optimal layout design of an LNG FPSO.

Evaluation of the Structural Stability of a Heave Compensator for an Offshore Plant and the Optimization of Its Shape.

Offshore plant designs can be broadly categorized into hull-type designs and topside module-type designs. Compared to the hull-type design, it is much more difficult to design the topside moduletype design due to the complexity of its structure, making the design technology of professional engineering companies critical. A heave compensation system is a system that compensates the vertical shock imposed on a drilling ship by waves, and is installed at the top of the topside module. Most researchers have used a mathematical model to investigate the analysis of the heave compensation system. This study will conduct a structural analysis using finite element software called Ansys to design a heave compensator that reduces the weight and secures the structural stability, and will derive the ideal design through an optimization process that utilizes the response-surface method and the Kriging model.

Use of built-up H sections as secondary members in topside modules

There have been many attempts to widely utilize built-up H sections to secure flexibility in structural design. Much research into the structural strengths and limit states of built-up H sections, therefore, has been carried out. However, a practical redesign methodology taking advantage of built-up H beams has yet to be introduced into the offshore industry. In this study, a comprehensive investigation into built-up H sections is carried out, based on which, a new redesign procedure for weight reduction herein is suggested. First of all, on the basis of the ANSI/AISC 360-10, the differences between the rolled H and built-up H sections are investigated in terms of their various strengths. Then, a secondary-member redesign procedure is established as a means of reducing structural weight by replacing rolled H sections with built-up H sections. In that procedure, the built-up H section cross-section is modified according to the failure modes of reference rolled H sections. The redesign procedure is verified by a nonlinear finite element analysis and four-point bending test. Through the nonlinear finite element analysis and experiment on the reference rolled H section and built-up H section obtained by the redesign procedure, it is observed that the weight of the built-up H section is reduced by about 15% while a flexural strength similar to that of the reference rolled H section is maintained. The suggested redesign procedure is then applied to three floating production storage offloading (FPSO) topside modules for demonstration purposes. In the results, the total structural weights of the reference topside modules are reduced by approximately 3%–5% by employing built-up H sections in secondary members in lieu of rolled H sections. The results indicate that, in many cases, built-up H sections can be used as secondary members to reduce the structural weight of topside modules.

Experimental and numerical study on mating operation of a topside module by a floating crane vessel in waves

In this study, an experimental and numerical study was conducted for investigating the mating operations of a topside module onto a FLNG by using a floating crane in waves. A series of model tests were performed in Ocean Engineering Basin at KRISO with a model set-up of 1:45 scale ratio. The floating crane vessel was equipped with a crane system and dynamic positioning system. The topside module was simplified as a rectangular box of about 2000 Tonf. Four leg mating units(LMUs) were introduced to model the interface units between the FLNG and the topside module. While the interaction forces between the crane vessel and the topside module are transferred via the crane wires, the topside module interacts with the FLNG through the LMUs. Experimental conditions include four different mating stages, i.e. 0%, 20%, 50% and 93% load transfers, under regular and irregular wave conditions. To validate the experimental data, a time-domain numerical simulation method is applied to solve the coupled dynamics of three bodies. The discussions were made on three main points. First, the motion characteristics of the lifted object as well as the crane vessel were investigated by comparing the simulation results. Second, the dynamic tensions of the crane wires were evaluated under the various wave and mating conditions. Final discussion was made on the LMU impact forces.

Fully Coupled Analysis of an Offshore Deck Mating Operation of a Large Topside Module

Fully Coupled Analysis of an Offshore Deck Mating Operation of a Large Topside Module

A Study on the Structural Behavior of FPSO Topside Module by Support Condition

A Study on the Structural Behavior of FPSO Topside Module by Support Condition