Steel Lazy Wave Riser Design for Semi-Submersible in Harsh Environment

2014 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao
Keyword(s):  
Water Depth ◽  
Optimal Solution ◽  
Cost Effective ◽  
Harsh Environment ◽  
Depth Range ◽  
Strength Performance ◽  
Field Development ◽  
Steel Catenary Risers ◽  
Riser Design ◽  
Design Guidance

Deep draft production semi-submersible with steel lazy wave risers (SLWRs) has been studied for the 2,625ft water depth in harsh environment. The design challenges and feasibility of steel catenary risers (SCRs) for semi-submersible at relatively shallow water and harsh environment are discussed. The benefits of using SLWRs to improve riser strength and fatigue performance are presented. Due to the complexity of SLWR geometry, a systematic configuration approach is introduced to achieve the desired riser performance target. A comparison study on fatigue and strength performance of various riser configurations is performed. The assessment provides design guidance for the optimal solution of the integrated hull, mooring and riser system. It concludes that deep draft production semi-submersible with SLWRs can be a feasible and cost effective solution for field development at water depth range from 2,297ft to 3,281ft in harsh environment.

Design of Steel Lazy Wave Riser for External Turret Moored FPSO

2019 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao
Keyword(s):  
Water Depth ◽  
Optimal Solution ◽  
Cost Effective ◽  
Fatigue Performance ◽  
Effective Solution ◽  
Field Development ◽  
Riser Design ◽  
Preferred Solutions ◽  
Design Challenges ◽  
Selection Of

Abstract The external turret moored Floating Production Storage and Offloading system (FPSO) is one of the preferred solutions for deepwater fields in mild to moderate environments and far away from existing pipeline infrastructures. This paper presents a design of steel lazy wave riser (SLWR) system for an external turret moored FPSO in the water depth of 1,500 meter. The design challenges and feasibility are discussed. Due to the complexity of SLWR geometry, a systematic configuration approach is introduced to achieve the desired riser extreme and fatigue performance target, as well as external turret layout. The study includes the standardized FPSO, the selection of turret configuration, and riser design. The titanium taper stress joints and the interaction with turret structure are also studied. The study provides an optimal solution of the integrated turret, mooring and riser system. It concludes that external turret FPSO with SLWRs can be a feasible and cost effective solution for field development in mild to moderate environments.

Wet Tree Semi-Submersible With SCRs for 4,000 ft Water Depth in the Gulf of Mexico

2011 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao ◽  
Sherry Xiang
Keyword(s):  
Gulf Of Mexico ◽  
Water Depth ◽  
Cost Effective ◽  
Integrated System ◽  
Fatigue Performance ◽  
Strength Performance ◽  
Field Development ◽  
Vessel Motion ◽  
Optimum Solution ◽  
Mitigation Methods

This paper presents a design of a deep draft wet tree semi-submersible with steel catenary risers (SCRs) for 4,000 ft water depth in the Gulf of Mexico (GoM). The integrated system of hull, mooring, and SCRs is discussed. The design challenges of SCRs are highlighted and results of SCR strength and fatigue performance are presented. A comparison study on strength performance of various types of risers under the GoM environment criteria is performed. The assessment of extreme strength responses from various riser and hull configurations provide guidelines for the best hull selection. Sour service requirement creates challenges in the fatigue design of the production riser system at such water depth. Integrated mooring and riser design provides an optimum solution. It’s found that the majority of riser fatigue damage at touch down zone is generated by wave loading & resultant vessel motion and vortex induced vessel motion (VIM). Several fatigue mitigation methods are suggested to improve the riser fatigue performance, such as planned vessel repositioning. The conclusion of this study is that deep draft wet tree semi-submersible with SCRs can be a cost effective solution for field development at 4,000 ft water depth in the Gulf of Mexico.

Deep Draft Semi Submersible

2002 ◽  
Author(s):  
Arne Ulrik Bindingsbo̸ ◽  
Arve Bjo̸rset
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Water Depth ◽  
Flexible Riser ◽  
Production Platform ◽  
Steel Catenary Risers ◽  
Riser Design ◽  
Flexible Risers ◽  
Gas Fields ◽  
Preferred Solutions

High Pressure and High Temperature wells together with harsh environmental conditions puts a tough challenge on the flowline and riser design. The flexible riser which has been the favorite choice for many field developments with subsea wells have several technical limitations. Large gas fields such as Ormen Lange require large bore export risers. Steel risers are the preferred solutions with respect to durability and cost. Unfortunately, it is difficult for steel risers to accommodate the vessel motions of a semi submersible or ship. Heave restricted vessels such as TLP or SPAR are used together with toptensioned risers and surface trees. Based on the limitations of flexible risers Hydro is pursuing extensive research on riser and floater technology. As part of this research program a study on the effect on riser design caused by reducing vessel motions. The main goal is to introduce steel catenary risers (SCR) on semi submersible platforms. The typical draft of a semi submersible production platform is 20–25 m. By reengineering the design of such a platform and increasing the draft from 21 m to 40 m the vessel motions were reduced significantly. Hence, an opening for novel riser solutions was made. ULS and FLS analyses for 10″ and 30″ SCR in 300 and 1000 m water depth were carried out. The key result is that the 10Prime; riser satisfies both the ULS and FLS requirement for both vessel drafts and water depth and the 30Prime; riser satisfies the both the ULS and FLS requirement for the 40 m vessel draft at 1000 m water depth.

Design of Steel Lazy Wave Riser for Disconnectable FPSO in the Gulf of Mexico

2013 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao
Keyword(s):  
Gulf Of Mexico ◽  
Water Injection ◽  
Integrated Design ◽  
Cost Effective ◽  
Performance Criteria ◽  
Harsh Environment ◽  
Effective Solution ◽  
Field Development ◽  
Integrated Design Approach ◽  
Preferred Solutions

The disconnectable Floating Production Storage and Offloading system (FPSO) is one of the preferred solutions for the deepwater field in the harsh environment and far away from existing pipeline infrastructures. This paper presents a design of steel lazy wave riser (SLWR) system for an internal turret moored disconnectable FPSO in the Gulf of Mexico. The integrated systems of FPSO, disconnectable buoy, riser, and mooring are discussed while focusing on the design challenges of SLWR system. Due to the complexity of SLWR geometry, a systematic configuration approach is introduced based on buoy payload and riser performance criteria. The study includes the strength and fatigue analysis of production, gas export and water injection risers for the connected, disconnecting, and disconnected conditions. The sensitivity of buoy disconnecting due to vessel offset is also presented. It concludes that SLWR with disconnectable FPSO is a feasible and cost effective solution for deepwater field development in the Gulf of Mexico. The study demonstrates the importance of an integrated design approach, and provides guidance for configuring and design of future disconnectable systems with SLWRs.

Steel Lazy Wave Riser Configuration for Turret Moored FPSO With Disconnectable Turret in Deepwater

2015 ◽  
Author(s):  
Daniel Karunakaran ◽  
Sankar Subramanian ◽  
Rolf Baarholm
Keyword(s):  
Deep Water ◽  
Cost Effective ◽  
Attractive Alternative ◽  
Harsh Environment ◽  
Detailed Case ◽  
Effective Manner ◽  
Water Developments ◽  
Pros And Cons ◽  
Steel Catenary Risers

Recently turret-Moored FPSOs have been used in many deep water developments worldwide, with consideration of disconnectable turrets for harsh environment applications. This trend makes the interactions between FPSO and risers system more important. Further, Steel Lazy Wave Risers (SLWR), which is a compliant variant of the mostly commonly used Steel Catenary Risers (SCR), is becoming an attractive riser option. The paper provides a review of the various riser systems that can be considered for turret-moored FPSOs, and specific emphasis on Steel Lazy Wave Risers. A detailed case study of Steel Lazy Wave Risers for a typical turret moored FPSO with disconnectable turret is presented. This system is described in terms of design and functionalities, the fabrication and installation methods are presented. The case study shows clearly that SLWR are an attractive alternative to be used for FPSO with disconnectable turret and is very efficient to fabricate and install in a very cost effective manner. Pros and Cons for SLWR are discussed, with consideration of the particular challenges of turret-moored FPSOs with large floater motions, hang-off geometry constraints at turret, hang-off loads, riser interferences, risers pre-installation, and turret disconnection constraints.

Tethered Catenary Riser: A New Deepwater Concept

2013 ◽  
Author(s):  
Jean-Luc Legras ◽  
Baptiste Pillet
Keyword(s):  
Cost Effective ◽  
Field Development ◽  
Dynamic Excitation ◽  
Sea Bed ◽  
Engineering Work ◽  
Heavy Lift ◽  
Water Developments ◽  
Steel Catenary Risers ◽  
The One ◽  
Single Pipe

A new riser concept is proposed by Subsea 7 for field development in deep and ultradeep waters: the Tethered Catenary Riser (TCR)-patent pending. The concept consists of a number of steel catenary risers (SCRs) supported by a subsurface buoy which is tethered down to sea-bed by means of a single pipe tendon and anchored by means of a suction pile; flexible jumpers are used to make the connection between the Floating production Unit (FPU) and the buoy. Umbilicals run without interruption from the FPU to their subsea end while being supported by the buoy. The system has all the advantages of de-coupled riser arrangements: flexible jumpers effectively absorb platform motions, thereby the rigid risers and tendon have very small dynamic excitation. The system can be installed before FPU arrival on site, which improves the time before first oil. Analyses have shown that, with adequate geometry of the buoy, the latter is sufficient stable to induce acceptable tilt and twist when different arrangements of SCRs and flexible jumpers are installed, and under accidental scenarios during the in-place life. The riser system is best designed for a number of risers between 4 and 8, in addition to a number of umbilicals, thus convenient for one or two drilling centers. Results of the basic engineering work on the TCR clearly indicate that it is possible to have a robust design using presently qualified materials and technology. The components used in the TCR are all field proven as they are commonly used in existing riser systems. As a result of installation studies, a method very similar to the one commonly used by Subea7 for Single Hybrid Risers (SHRs) has been selected for the buoy and tether system. Placement of rigid risers, jumpers and umbilicals is as done by Subsea 7 for the Buoy Supporting Risers (BSRs). This method is well adapted for installation by the new Subsea 7 flagship vessel Seven Borealis which is able to perform heavy lift and pipe laying. The Tether Catenary Riser is a credible option for use in deep water developments all over the world. Since all the components, design methods and installation procedures are fully qualified and familiar to Subsea 7, the concept is cost effective and ready for project application.

scholarly journals COBRA Riser Concept for Ultra Deepwater Condition

2013 ◽  
Author(s):  
Tomy Nurwanto ◽  
Daniel Karunakaran ◽  
Ricardo Franciss
Keyword(s):  
Water Depth ◽  
Oil And Gas ◽  
Sudden Change ◽  
Cost Effective ◽  
Mooring Lines ◽  
Strength Performance ◽  
Design Performance ◽  
Cluster Region ◽  
Sea Bed ◽  
Flexible Jumper

Offshore ultra deepwater field is being promising as the future of oil and gas reserves. However, the development of ultra deepwater field posed many challenges, in particular, on the selection of the riser concept. Long suspended length of riser will significantly increase the vessel payload. High external hydrostatic pressure on the riser will increase the probability of collapse failure. Large dynamic motions of the vessel and large vessel offset yields potential buckling issues at the touch-down-point (TDP). In addition, potential fatigue problems due to vessel motions and soil-riser interactions also present at TDP area. Large current speed in deepwater field might also lead to vortex induced vibration (VIV) which eventually will contribute to significant fatigue damage for particular riser sections. By looking into these challenges, it is very important to select the most appropriate riser concept for the ultra deepwater field. Catenary Offset Buoyant Riser Assembly (COBRA) as newly developed hybrid riser concept offers a solution to overcome the challenges in ultra deepwater field. In general, COBRA consists of a catenary riser section with a long-slender sub-surface buoyancy module on top which is tethered down to sea bed via two mooring lines. The catenary section from top of the sub-surface buoy is connected to the floater by a flexible jumper. This flexible jumper can effectively absorb the floater motions, which give significant improvements for both strength and fatigue performance on the overall system. As a hybrid riser concept, this concept offers cost effective solution by avoiding all the expensive bottom assemblies that normally needed for a hybrid riser concept. This paper focuses on COBRA riser concept specifically for Santos Basin Central Cluster region at 2200 m water depth. It is observed that there is common sudden change phenomenon on the current direction in Santos Basin area. The effect of bidirectional current is analyzed, and the comparison with unidirectional current is discussed thoroughly. The analyses are focused on the global strength design performance under extreme environmental load and global fatigue design performance of the riser due to wave induced and VIV induced. The results clearly indicate that COBRA riser concept has a robust design and it is feasible for 2200 m water depth, in particular for Santos Basin Cluster Region area. It is also shows that COBRA riser has sufficient strength performance even for extreme bidirectional current.

Tension-Based Tension Leg Platform: Technologies for Ultra Deepwater Applications

2010 ◽  
Author(s):  
Nagan Srinivasan
Keyword(s):  
Water Depth ◽  
Oil And Gas ◽  
Cost Effective ◽  
Gas Production ◽  
Harsh Environment ◽  
Tension Leg Platform ◽  
Oil And Gas Production ◽  
Sea Bed ◽  
Horizontal Wave ◽  
Vibration Problems

This paper is about technology of the Tension Leg Platform (TLP) for use in ultra deepwater to support dry-tree in oil and gas production. New TLP concept for ultra deepwater development is introduced in this paper. A technically feasible and cost-effective artificial sea-bed is used to ease the tendon design practical at such deep water in harsh environment. The truss-pontoon is utilized to reduce the vertical and horizontal wave loadings. A simple and slim hull easy to design, fabricate, transport and install is obtained. Installation method is illustrated. Optional riser-support tower is proposed to make production risers feasible in 8000 ft of water depth with no riser pre-tension to the hull and with no vortex induced vibration problems. The paper enhances the TLP capability in deepwater.

scholarly journals Economic Development Based on a Mathematical Model: An Optimal Solution Method for the Fuel Supply of International Road Transport Activity

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2963
Author(s):  
Melinda Timea Fülöp ◽  
Miklós Gubán ◽  
György Kovács ◽  
Mihály Avornicului
Keyword(s):  
Decision Making ◽  
Ad Hoc ◽  
Market Competition ◽  
Optimal Solution ◽  
Cost Savings ◽  
Cost Effective ◽  
Optimization Method ◽  
Optimal Decision ◽  
Environmental Damage ◽  
Fuel Cost

Due to globalization and increased market competition, forwarding companies must focus on the optimization of their international transport activities and on cost reduction. The minimization of the amount and cost of fuel results in increased competition and profitability of the companies as well as the reduction of environmental damage. Nowadays, these aspects are particularly important. This research aims to develop a new optimization method for road freight transport costs in order to reduce the fuel costs and determine optimal fueling stations and to calculate the optimal quantity of fuel to refill. The mathematical method developed in this research has two phases. In the first phase the optimal, most cost-effective fuel station is determined based on the potential fuel stations. The specific fuel prices differ per fuel station, and the stations are located at different distances from the main transport way. The method developed in this study supports drivers’ decision-making regarding whether to refuel at a farther but cheaper fuel station or at a nearer but more expensive fuel station based on the more economical choice. Thereafter, it is necessary to determine the optimal fuel volume, i.e., the exact volume required including a safe amount to cover stochastic incidents (e.g., road closures). This aspect of the optimization method supports drivers’ optimal decision-making regarding optimal fuel stations and how much fuel to obtain in order to reduce the fuel cost. Therefore, the application of this new method instead of the recently applied ad-hoc individual decision-making of the drivers results in significant fuel cost savings. A case study confirmed the efficiency of the proposed method.

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