scholarly journals Integrity of Subsea Control Umbilical

Author(s):  
Ramin Yasseri ◽  
Sirous Yasseri ◽  
Bin Wang

Controlling subsea oil and gas production systems requires fibre optics, power cables and tubes for the transportation of chemical for injection and fluid for hydraulic controls. These are arranged in helical bundles in successive layers. Shaped thermoplastic fillers are used to separate components and to fill out voids in the cross section. If necessary, armour is added to provide strength for the dynamic loads. This paper describes the application of 3D finite element method to assess the structural Integrity of subsea umbilicals, including the interaction between the constituent elements. It is suggested to uses a global analysis to determine the internal forces and local analyses (sub-modelling) for detailed stress evaluation. Abaqus is used for this purpose, due to its capability with large size problems under severe discontinuities due contact conditions. This paper also discusses the umbilicals interaction with seabed. The focus of this paper is on the fatigue life calculation.

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1849 ◽  
Author(s):  
Adriana Velloso Alves de Souza ◽  
Francisca Rosário ◽  
João Cajaiba

Calcium carbonate scale is formed during oil and gas production. Tube-blocking tests (TBTs) are used to define the minimum inhibitory concentration (MIC) in order to prevent scale adhesion in the petroleum production system equipment. However, non-adhered crystals may favor heterogeneous nucleation to other deposits such as calcium naphthenates, causing a more severe scale problem, increasing production losses and treatment costs. The objective of the present work was to develop a new dynamic test methodology to determine the MIC for CaCO3 using a sintered metal filter. Organophosphorus inhibitors were selected for comparison with the conventional dynamic tube-blocking system. The results demonstrated that the use of the filter allowed an MIC of the inhibitors to be obtained considering the precipitation prevention. The inhibitor concentration in the conventional tube-blocking system does not prevent precipitation, acting only on adhesion and crystal growth on the capillary wall. Tests to evaluate the potential of calcium naphthenates formation in a naphthenate flow rig dynamic system demonstrated the influence of heterogeneous nucleation from non-adhered carbonate crystals, potentially aggravating deposition problems in oil and gas production systems.


2020 ◽  
Author(s):  
Meziane Akchiche ◽  
Jean-Louis Beauquin ◽  
Sabine Sochard ◽  
Sylvain Serra ◽  
Jean-Michel Reneaume ◽  
...  

2012 ◽  
Vol 479-481 ◽  
pp. 1129-1132
Author(s):  
Wang Ming Bo

This paper gives an overview of erosion mechanisms in elbows in oil and gas production systems. The nature of the erosion process itself makes it very difficult to develop some definitive methods or models to prevent or predict the erosion in elbows in all conditions. This paper provides a review of the subject which will help petroleum engineers to handle the erosion problems in oil and gas industry. This review is given of different erosion mechanisms connected with sand erosion and the factors that influence them, and then the review goes on to look at particulate erosion in elbows in more details. Conclusions are then drawn based on the above analyses.


Author(s):  
Michelangelo Fabbrizzi ◽  
Paolo Di Sisto ◽  
Roberto Merlo

Subsea oil and gas production systems can be subject to Hydrogen Induced Stress Cracking (“HISC”) depending on the material, cathodic protection and other factors. A failure in this kind of systems can lead to safety issues as well as environmental hazards and high repair costs. The analysis of recent failures has led to the recognition of HISC as a very important issue related to local stress and strain. This has necessitated the extensive use of Finite Elements Methods for the analysis of all system components. Since HISC is a recent issue, there are very few cases of such assessments reported in the literature. This paper is based on the assessment of the susceptibility of subsea piping manifolds of Duplex stainless steel to Hydrogen Induced Stress Cracking, which was conducted during the Skarv project by General Electric Oil & Gas. A variety of cases consisting of different loads and configurations were considered to give a broad assessment using a recently developed code (DNV-RP-F112-October2008). This work has led to the development of a set of procedures and models for the assessment of the entire system which is described in the current paper. The proposed methodology is useful for both design purposes and also for the verification of parts, which, if found to be non-compliant, would require redesign. In general, parts that were determined to be non-compliant using a linear assessment were found to be compliant through non-linear analysis, in fact 3D plastic analysis leads to a redistribution of stress and strain and hence, to lower values. “Cold creep” was not considered since the levels of stress and strain were considered to be low enough to avoid this phenomenon. As a consequence of this experience, a new methodology was developed, which is able to speed up the analysis process and to predict local stresses from only pipe elements. The latter permits the use of a linear assessment for bends, T junctions and weldolet even with misalignment and erosion, avoiding the need to perform 3D analysis. The second part of the paper describes this method.


Author(s):  
Soheil Manouchehri ◽  
Guillaume Hardouin ◽  
David Kaye ◽  
Jason Potter

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.


Author(s):  
Per Egil Kvaale ◽  
Tore Ha˚brekke ◽  
Gisle Ro̸rvik

Use of stainless steels in subsea oil and gas production systems have been common through the development of remote controlled subsea oil and gas production systems. Stainless steels are mainly selected to minimize the corrosion due to unprocessed oil and gas and thereby simplifying the internal corrosion protection challenges. Different materials and principles have been implemented from cladding of Carbon Manganese steels to the use of solid stainless steels. For cladding Incoloy 825 or Inconel 625 is common, while the solid stainless steels have been duplex, superduplex or 13%Cr steels in pipes and pipe fittings. Experience from service has shown that these materials have limits in their use, and it is reported various cases where the stainless steels have failed. The present paper will deal with a few examples of failures and possible reasons for these failures.


Author(s):  
Do-Jun Shim ◽  
Fredrick Brust ◽  
Gery Wilkowski

Environmental cracking, such as stress-corrosion cracking (SCC), is a significant issue for a variety of industries, such as those dealing with power generation — nuclear, oil and gas production, and pipeline transmission, etc. SCC is particularly of concern in that catastrophic failures can occur even at low applied stress levels (e.g., residual stress produced by welding). Thus, it is critical to evaluate the behavior of SCC for structural integrity assessments. In this paper, three different crack growth methods (i.e., idealized crack growth analysis, crack growth analysis using finite element alternating method; FEAM, and the natural crack growth method) are summarized. These methods all utilize the stress intensity factor for crack growth evaluations. Thus, these methods can be used for assessment of environmental cracking that is based on stress intensity factor. Various examples are shown in this paper to demonstrate the applicability of these methods. Comparisons of results obtained from different methods are also provided in this paper.


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