otc18669.pdf，otc18691.pdf
Doc Number: OTC018669 - Title: J-Lay and Steep S-Lay: Complementary Tools for Ultradeep Water
Authors: Dominique Perinet and Ian Frazer, Acergy
Year: 2007
Summary:
J-Lay and Steep S-Lay Complementary Tools for Ultradeep Water. Page 8 8 OTC 18669 conventional equipment where the capacity is not always in line with the deep water requirement. From a weather down time point of view and fatigue damage during the laying , the gimballing J-lay is much more favourable than the S-lay. However the S-Lay is the more efficient and with the adapted criteria can allow economical construction of long pipelines in deep water This paper has addressed the suitability of various pipelay techniques for deep water particularly the S-Lay and J-Lay techniques. A summary of the main conclusions is presented below :- 1. The extension of the S-Lay seems a very appropriate technique for laying long trunkline in deep water and medium or large diameter flowlines. This is feasible today with the new laying criteria of the steep S lay. 2. For the short flowlines to be installed on a field, including subsea structures the utilisation of the J-Lay technique seems more appropriate. The installation of these structures over the lines is a major issue, and the time for assembly the current section of the pipeline is not the most relevant factor. The required J-ramp for such cases does not need to be very long for two reasons : as explained the current laying time is no more the more driving parameter and with a short tower it is possible to accommodate two working stations. 3. The reel technique for medium diameter flowlines may offer a good technical and economical solution. This technique is appropriate for laying pipelines including continous anticorrosion internal
Doc Number: OTC018691 - Title: Sand Transport Modeling in Multiphase Pipelines
Authors: Thomas J. Danielson, ConocoPhillips Co.
Year: 2007
Summary:
Page 9 OTC 18691 9 0.0 0.5 1.0 1.5 2.0 2.5 0.0 0.2 0.4 0.6 0.8 1.0 1.2 mixture velocity (m/s) gas,liquid,andsandvelocity(m/s) gas velocity liquid velocity sand velocity Figure 5. Plot of gas, liquid, and sand velocity predicted by the multiphase sand model. Note that the difference between the sand and liquid velocity is maintained at a contant value, equal to the critical velocity UC. 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 0.0 0.2 0.4 0.6 0.8 1.0 1.2 mixture velocity (m/s) liquidandsandhold-up(-) liquid hold-up sand hold-up Figure 6. Liquid and sand hold-ups corresponding to the velocities in Figure 5. Note that the liquid hold-up drops as the sand hold-up increases; the overall hold-up is well-described by a drift-flux type model formulation. Page 10 10 OTC 18691 0 0.05 0.1 0.15 0.2 0.25 0 1 2 3 4 5 6 7 8 9 10 superficial gas velocity (m/s) superficialliquidvelocity(m/s) Figure 7. Prediction of the border beween sand bed formation and no sand bed formation for air-water-sand flow. This theoretical result quantitiatively matches the experimental data of Angelsen. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 superficial water velocity (m/s) sandhold-up(-) experiment olga model Figure 8. Test of the OLGA, modeling sand as a pseudo-phase with a slip velocity equal to the critical velocity UC measured in the SINFEF liquid-sand experiments. This shows that OLGA can be used to predict sand bed formation in single-phase flow. Since the slip between the sand and liquid is not a
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