An Innovative FPSO Design Hosting SCRs in the North Sea Harsh Environment

2016 ◽  
Author(s):  
Alaa M. Mansour ◽  
Ricardo Zuccolo ◽  
Cheng Peng ◽  
Chunfa Wu ◽  
Bill Greiner ◽  
...  
Keyword(s):  
North Sea ◽  
Rectangular Cross Section ◽  
Large Diameter ◽  
Harsh Environment ◽  
Efficient Production ◽  
The Novel ◽  
Capital Costs ◽  
The North ◽  
The North Sea ◽  
Novel Design

Floating Production Storage and Offloading (FPSO) floaters have the advantages of providing the required storage in the hull and direct offloading to tankers of opportunity in deep and ultra-deep water in areas lacking infra-structure. Steel Catenary Risers (SCRs) are the preferred solution in wet-tree applications due to their simplicity, robustness and low Capital costs (CAPEX) and Operational costs (OPEX) compared to other riser options. However, due to its relatively high dynamic motions, FPSO is not a feasible host for SCRs in most environments and especially so in the North Sea very harsh environment. Also, for efficient production from rich reservoirs, large diameter and number of risers are typically required. This makes it more challenging to find a robust and commercially attractive riser solution. In this paper a novel design for an FPSO with the ability to host SCRs in the North Sea very harsh environment is presented and evaluated. The novel design, namely, Low Motion FPSO (LM-FPSO), has a hull form with a generally rectangular cross-section. The platform is moored in-place using a conventional mooring system. The LM-FPSO performance is enhanced with the robust low-tech feature, namely, free-hanging solid ballast tank (SBT). The SBT is located certain distance below hull keel and connected to the hull through four groups of short tendons. All tendon components are the same as those used in conventional TLPs. Through the mass and added mass of the SBT, the LM-FPSO provides significantly improved heave, roll and pitch responses. The paper presents detailed description of the novel North Sea LM-FPSO design and its in-service performance. The SCR’s feasibility is discussed. The identified risks and associated mitigations for the new design compared to the conventional FPSO are investigated and reported. The paper concludes with discussions on the project execution plan and cost benefit when developing fields using this novel design.

scholarly journals Development and field test of a mobile continuous flow system utilizing Chemcatcher for monitoring of rare earth elements in marine environments

2016 ◽  
Vol 2 (1) ◽  
pp. 146-153 ◽  
Author(s):  
Jördis Petersen ◽  
Daniel Pröfrock ◽  
Albrecht Paschke ◽  
Jose A. C. Broekaert ◽  
Andreas Prange
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Field Test ◽  
North Sea ◽  
Continuous Flow ◽  
Flow System ◽  
Field Testing ◽  
The Novel ◽  
The North ◽  
The North Sea

Field testing of the novel system during a cruise in the North Sea yielded precise TWA concentrations of the analytes.

Efficient Indicators for Screening of Random Waves for Wave Impacts on a Jacket Platform and a Fixed Offshore Wind Turbine

2019 ◽  
Author(s):  
Tim Bunnik ◽  
Jule Scharnke ◽  
Erik-Jan de Ridder
Keyword(s):  
North Sea ◽  
Large Diameter ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Probability Level ◽  
Wave Impact ◽  
The North ◽  
Statistical Variation ◽  
The North Sea ◽  
Design Loads

Abstract Renewed interest in wave impact assessment has risen for various reasons: • The low airgap of some existing Mobile Units in the North Sea • The COSL Innovator incident and related to this topic the new DNV-GL guidelines (OTG 13 and OTG 14). • the installation of many large-diameter monopile foundations for wind turbines in increasingly deep water in the North Sea. • The installation of many large-diameter wind turbines in increasingly deep water in the North Sea. • Seabed subsidence (and maybe water level rises due to global warming) and their effect on the decreasing airgap of fixed platforms. Wave impact assessment has been the subject of many recent studies and research projects, and there has been a strong knowledge and tool development during the last decade, both within model testing and numerical (CFD) analysis (Huang et.al (2017), de Ridder et.al, (2017), Vestbøstad et. al. (2017), Bunnik et.al. (2018)). However, there is still a lack of efficient methods and tools to properly analyze wave impacts and derive the statistical variation of these impacts in the sea states to which these structures are exposed during their lifetime. To reduce the statistical uncertainties that are naturally arising in estimates of design loads related to extreme waves, sufficient data must be gathered. In order to estimate the design loads it is common practice not to investigate all possible sea states (i.e. long-term analysis) but to investigate a few sea states and assume that the design value occurs at a prescribed probability level in the sea states with the same probability level (i.e. contour line approach). The estimate of the design value at that probability level is then based on results from a limited number of random realizations of these sea states. For linear or weakly nonlinear response types it is possible to estimate design loads accurately with a quite limited number of realizations. For strongly nonlinear problems however this is not possible due to the large statistical variation in the maximum observations, inherent to a random nonlinear process. Estimating accurately the tail of the load distribution requires many more realizations. This approach is restricted by time and costs and eventually one may have to accept an estimated design load with a large statistical uncertainty and account for the uncertainty with a higher safety margin. In this paper an improved methodology for estimating design loads related to extreme wave impacts will be presented. The methodology is based on screening many 3-hour realizations of the design sea states with simplified, fast but sufficiently accurate methods and to focus only on the potentially critical events with a model containing a more complete description of the physics. This can be either a model test or a non-linear impact simulation (i.e. CFD analysis). By doing this many more rare/critical events can be assessed, reducing the statistical uncertainty in the estimate of the design load. A screening method/wave impact indicator will be presented for a jacket platform and for a fixed offshore wind turbine. Existing model test data is used to show the correlation between indicator and actual impact events and to derive the efficiency of the impact indicators.

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