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dc.contributor.advisorSkalle, Pål
dc.contributor.authorMehari, Mehari Redae
dc.date.accessioned2019-09-11T09:02:53Z
dc.date.created2016-07-21
dc.date.issued2016
dc.identifierntnudaim:15268
dc.identifier.urihttp://hdl.handle.net/11250/2615225
dc.description.abstractResearches in the industry have always ascertained that mud channels affect the two principal objectives of primary cement job; zonal isolation and structural support. This can lead to envi- ronmentally, operationally hazardous well. Velocity profile of cement slurry flow, due to no-slip boundary condition, is among the reasons behind mud channeling. This study aims at cement displacement efficiency based on investigation of operational parameters and conditions that control the nature of velocity profile. The effects of cement rheology, flowrate, flow regime, pipe roughness, and contact time are analyzed through model equations and experiments for laminar and turbulent flow of Newtonian, Bingham plastic, and Power-law fluids in a horizontal pipe. Eulerian method of flow description is employed to locate fluid interface through time along a radially discretized control volumes. The respective effect of viscosity and flow rate on displacement efficiency was studied both under turbulent and laminar flow conditions. Increase in flowrate followed by surpass of critical Reynolds number brings robust displacement efficiency. Around 15% theoretical displacement efficiency superiority of turbulent regime over laminar flow was recorded at the tested conditions for both Newtonian and Power-law fluids. After turbulent flow is reached, an increase of flow rate brought slight decrease of efficiency for Bingham and Power-law fluids while efficiency of Newtonian fluid still increases. The main reason is shear thinning behavior of the non- Newtonian fluids which leads spearheading at high rate. A decrease of viscosity that brings higher displacement efficiency when critical Reynolds number is exceeded. However, decrease of apparent viscosity during laminar flow of Bingham fluids resulted in decrease of efficiency as it led to narrow plug flow radius. Pipe roughness and contact time increased efficiency. Results of this study suggested that cement should necessarily displace mud in turbulent flow. Laminar cement displacement led cement to channel through mud which prevent accom- plishment of zonal isolation and casing support during primary cement job. This impact wors- ens for long, horizontal well cementing since mud remained can be locked and unable to be removed even at higher pumped cement volumes. Lowering cement rheology within practical limits improves cement placement and enhance turbulent flow operationsen
dc.languageeng
dc.publisherNTNU
dc.subjectPetroleum Engineering, Drilling Engineeringen
dc.titleCement Displacement Efficiency in Smooth and Rough Pipes - An Experimental and Theoretical Investigationen
dc.typeMaster thesisen
dc.source.pagenumber101
dc.contributor.departmentNorges teknisk-naturvitenskapelige universitet, Fakultet for ingeniørvitenskap,Institutt for geovitenskap og petroleumnb_NO
dc.date.embargoenddate10000-01-01


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