Υπολογιστική διερεύνηση πολυφασικής ροής υγρών-αερίων-στερεών σε κατακόρυφους αγωγούς μεγάλου μήκους και εφαρμογή σε εγκαταστάσεις εξόρυξης πετρελαίου

• Main Authors: Giannoulis, Dimitrios-Periklis, Γιαννούλης, Δημήτριος-Περικλής
• Format: Doctoral or Postdoctoral Thesis
• Language: Greek
• Published: University of Patras 2018
• Subjects: Πολυφασική ροή; Multiphase flow; Επιστήμες Μηχανικού και Τεχνολογία; Επιστήμη Μηχανολόγου Μηχανικού; Engineering and Technology; Mechanical Engineering; Norne field
• Online Access: http://hdl.handle.net/10442/hedi/43725; https://doi.org/10.12681/eadd/43725

The aim of the present doctoral thesis is the computational investigation of the multiphaseflow formed inside the DIFIS system during its use for prompt intervention in cases of offshoresubsurface blowouts.The DIFIS system consists of an inverted funnel (dome), which initially collects the leakingmixture, a riser tube and a buffer bell. It was originally designed for intervention in cases ofleakage from shipwrecks, based on the difference between oil and sea-water densities, whichcreates the necessary buoyancy in order to channel the leaking oil through the riser tubetowards the buffer bell.In cases of underwater blowouts, the presence of natural gas in the leaking mixture incombination with the highly increased flow rates compared to shipwrecks, as well as theexistence of sea-currents that can drift the mixture out of the system, necessitate a revision ofthe dimensions and the position of the system, in order to ensure trouble-free operation. Thetypes of two, three and four phase flows developed in the interior are examined, with thepresence of sea-water and quantities of oil, methane and methane hydrates.In the first stage, a preliminary study is carried out, using a theoretical model based onhomogeneous two-phase water-oil flow, and then two-dimensional axisymmetric and threedimensionalcomputational simulations were conducted, in which 4 types of oil of differentproperties were studied.Then, for a more detailed study of the system, two indicative types of oil are selected, foundin the Gulf of Mexico (Mars crude oil) and in the Norne field (Svale crude oil), 200 km off theNorwegian coast, in order to initially examine the position in which the system should beplaced, taking into account for the first time, the conditions of sea-currents which are presentin the region of the leaking point, in order to ensure the absorption of the leaking mixture. For amore accurate estimation of the required configuration of the system’s bottom section, so thatit can respond to the typical conditions of the leakage, the ...