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dc.contributor.advisorNydal, Ole Jørgennb_NO
dc.contributor.authorKanu, Elizabethnb_NO
dc.date.accessioned2014-12-19T11:47:51Z
dc.date.available2014-12-19T11:47:51Z
dc.date.created2011-11-02nb_NO
dc.date.issued2011nb_NO
dc.identifier453362nb_NO
dc.identifierntnudaim:6364nb_NO
dc.identifier.urihttp://hdl.handle.net/11250/234500
dc.description.abstractFlow instabilities in long wells and risers under certain flow conditions, is well known. Expansion driven flow instability (EDI) which is relatively little known, refers to occurrence of flow instabilities in long wells and risers as a result of entrapment of gas upstream of the well or riser base. EDI can also occur in gas-lift systems at low pressure and low gas injection rate.This work was initiated to tackle flow instability problem related to deep water production operations where long wells and risers are extensively in use. The aim of this thesis is to investigate a type of flow instability known as Expansion Driven Flow Instability (EDI) in Long Wells and Risers . This involves experimental investigation as well numerical modelling of expansion driven flow instability in long wells and risers. Finally results of the experimental investigations are compared with numerical model data.An experimental flow loop was setup to verify EDI at varying pipe geometry, inlet flow pressure and gas flow rate to examine the effect of EDI in long wells and risers. The laboratory experiment was conducted using air and water at atmospheric conditions, in a flowline-riser system consisting of a 32mm diameter and 9.12m long riser. The expansion driven flow cycle was captured in video recording.Variation of inlet flow pressures was achieved by varying the height of the overflow tank. Three cases were considered, each at a different inlet pressure. Each inlet pressure of the fluid was examined against varying inclination angles of the horizontal pipe to the riser inlet. Different gas flow rates were tested at different inclination angles. It was observed that inclination angle has the greatest impact on EDI.Experimental result of one of the cases was modelled using OLGA and the results of the experimental compared against simulation results output. Discrepancies in the two sets of results were observed in some cases. These may be attributed to simplifications and assumptions made during the simulation model build.Both results of the experimental investigation and numerical simulation demonstrated that expansion driven flow instability can occur in laboratory setup and can probably occur in deep water natural-lift wells and risers as well as gas-lifted wells and risers under certain flow conditions and pipe inclinations. nb_NO
dc.languageengnb_NO
dc.publisherInstitutt for energi- og prosessteknikknb_NO
dc.subjectntnudaim:6364no_NO
dc.subjectMSGASTECH Natural Gas Technologyno_NO
dc.titleExpansion driven Unstable Two Phase Flows in Long Risers and Wellsnb_NO
dc.typeMaster thesisnb_NO
dc.source.pagenumber116nb_NO
dc.contributor.departmentNorges teknisk-naturvitenskapelige universitet, Fakultet for ingeniørvitenskap og teknologi, Institutt for energi- og prosessteknikknb_NO


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