Green Water Phenomena on a Twin-Hull FLNG Concept

2014 ◽  
Author(s):  
Riaan van ‘t Veer ◽  
Ebert Vlasveld
Keyword(s):  
Potential Flow ◽  
Oil And Gas ◽  
Gas Production ◽  
Point Of View ◽  
Green Water ◽  
Linear Potential ◽  
Oil And Gas Production ◽  
Large Wave ◽  
Water Problem ◽  
Offshore Industry

This paper investigates — based on model tests and potential flow calculations — several phenomena associated with the green water problem in severe sea states. The topics investigated are: the wave characteristics of the severe and steep sea states, the behavior of the vessel in these waves, the relative motions at the bow and the height of water on deck. The green water problem is of interest since many floaters used for the oil and gas production by the offshore industry are permanently moored for typically 20 years or more, and they will experience severe storm conditions with large wave heights. The investigations concern an unusual vessel type: SBM’s innovative midscale Twin-Hull FLNG concept [1]. The floater concept is to join two (standard) LNG carriers together to obtain sufficient storage volume and process deck space. The concept is under development and one aspect, from operability point of view, is the probability for green water. For this purpose a first model test campaign has been carried out. The Twin-Hull FLNG concept has been tested in extreme sea states which are typical for offshore Brazil and East-Africa. Linear potential flow calculations were applied to predict the freeboard exceedance based on relative motion amplitude operators. The correlation to the measured data is discussed. Although the research is dedicated to the Twin-Hull FLNG vessel, the observed phenomena are considered applicable to any stationary vessel in general.

On Determination of Acceptable Safety Class in Design of Pipe-In-Pipe (PIP) Systems

2014 ◽  
Author(s):  
Soheil Manouchehri ◽  
Guillaume Hardouin ◽  
David Kaye ◽  
Jason Potter
Keyword(s):  
Failure Modes ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Gas Production ◽  
Point Of View ◽  
Insulation Material ◽  
Limit States ◽  
Oil And Gas Production ◽  
Operational Conditions ◽  
Outer Pipe

Pipe-In-Pipe (PIP) systems are increasingly used in subsea oil and gas production where a low Overall Heat Transfer Coefficient (OHTC) is required. A PIP system is primarily composed of an insulated inner pipe which carries the production fluid and an outer pipe that protects the insulation material from the seawater environment. This provides a dry environment within the annulus and therefore allows the use of high quality dry insulation system. In addition, from a safety point of view, it provides additional structural integrity and a protective barrier which safeguards the pipeline from loss of containment to the environment. Genesis has designed a number of PIP systems in accordance with the recognized subsea pipeline design codes including DNV-OS-F101 [1]. In section 13 F100 of the 2013 revision, a short section has been included in which PIP systems are discussed and overall design requirements for such systems are provided. It has also been stated that the inner and outer pipes need to have the same Safety Class (SC) unless it can be documented otherwise. This paper looks at the selection of appropriate SC for the outer pipe in a design of PIP systems based on an assessment of different limit states, associated failure modes and consequences. Firstly, the fundamentals of selecting an acceptable SC for a PIP system are discussed. Then, different limit states and most probable failure modes that might occur under operational conditions are examined (in accordance with the requirements of [1]) and conclusions are presented and discussed. It is concluded that the SC of the outer pipe of a PIP system may be lower than that of the inner pipe, depending on the failure mode and approach adopted by the designer.

Some aspects of the shaped-charge perforator certification and qualification problem

2021 ◽  
Author(s):  
A.V. Babkin ◽  
N.V. Gerasimov ◽  
S.V. Ladov
Keyword(s):  
Large Scale ◽  
Oil And Gas ◽  
Organizational Factors ◽  
Gas Production ◽  
Point Of View ◽  
Shaped Charge ◽  
Physical Aspect ◽  
Oil And Gas Production ◽  
Certification Procedure ◽  
Cumulative Jets

The problem of certification of shaped-charge perforators appear to be very important in oil and gas production. The paper considers five aspects of the problem. First, it is a physical aspect, which means the problem is viewed from the point of view of the physics of a cumulative explosion; the second aspect is a methodological one, which implies the most desirable, permissible, unacceptable methods of certification and qualification; the next aspect is economic, it focuses on the economy on a large scale, allowing a possible loss in a small one. Perhaps, there are things that are currently more important than the most correct physical considerations and the most perfect methods, so technical and political aspects arise. The final aspect is an organizational one which implies a rational division of powers of government departments. The most important and science-intensive aspect is the physical one, as it is associated with the design, construction, and operation of shaped charges of perforators, and this is the main focus of the paper. The paper carefully analyzes the formation, movement in free space, and action on the combined obstacle: steel — concrete — rock of monolithic and powder cumulative jets from metal and composite materials. Moreover, the study comparatively assesses the penetrating action of shaped charges of perforators according to various methods, both domestic and foreign, and assesses economic, technical, political, and organizational factors in the development of the shaped charges certification procedure. Finally, the study gives recommendations for carrying out certification and qualification tests of shaped charges of perforators in Russia.

Breaking Load on Jacket Structure

2016 ◽  
Author(s):  
Sruthi Chandrasekar ◽  
Sriram Venkatachalam
Keyword(s):  
Wave Breaking ◽  
Oil And Gas ◽  
Impact Load ◽  
Breaking Load ◽  
Gas Production ◽  
Oil And Gas Production ◽  
Depth Analysis ◽  
Duhamel Integral ◽  
Offshore Industry ◽  
The Impact

Jackets are structures used in the offshore industry as a bottom supported platform for oil and gas production. The jackets have to be built in order to withstand the harsh sea environment. Such designs demand in depth analysis to predict the loads acting on the structure and its response. Depending on the sea states in which the structure needs to be installed, breaking load can be important. Estimation of breaking load for single cylinder exists in literature, since the breaking load on the jacket structure needs a lot more clarity. The aim of this paper is to estimate the impact force on a model jacket using Duhamel integral, which was not explored before. The impact load so far analyzed was compared with theoretical explanations given by Goda, et al. (1966), Wienke and Oumeraci (2005). The scope of the study is limited to plunging type of breakers. Five loading cases include wave breaking at far-front of a structure, in front of structure, on the front leg, on the rear leg and a non-breaking case was considered.

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