Article: Impact of surface choking on gas-lift stability and flow behaviour in oil producing wells Journal: International Journal of Oil, Gas and Coal Technology (IJOGCT) 2024 Vol.35 No.3 pp.258 - 278 Abstract: The effect of surface choking on gaslift stability and flow regime transition in vertical cylindrical pipe during gaslift operation is investigated. Here, a laboratory scale multiphase flow rig was designed, fabricated, and assembled. Gas rates of 0.000113 m3/s and 0.000187 m3/s were imposed on a 1 mm single nozzle injector. Surface choking was implemented by setting the system to 15%, 25%, 50% and 100% opening. For each opening condition, transient pressure at four locations; corresponding to length-to-diameter ratios of 0.0, 18.3, 36.7, and 53.3, was recorded. Flow structure and regime transition are characterised by visual, photographic and slow-motion videos, recorded at each location. A transition from random peak-to-peak cyclic and periodic pressure oscillation, accompanied by pressure increase, is observed. Further, bubble size reduction characterised by low vorticity and turbulence is observed at 15% opening. It is concluded that surface choking must be complemented by knowledge of flow behaviour within the system. [Received: June 14, 2022; Accepted: March 20, 2023] Inderscience Publishers - linking academia, business and industry through research

Title: Impact of surface choking on gas-lift stability and flow behaviour in oil producing wells

Authors: Joao Chidamoio; Lateef Akanji

Addresses: Center of Studies in Oil and Gas Engineering and Technology, Eduardo Mondlane University, Maputo, Mozambique ' School of Engineering, College of Physical Science, University of Aberdeen, Aberdeen, Scotland, UK

Abstract: The effect of surface choking on gaslift stability and flow regime transition in vertical cylindrical pipe during gaslift operation is investigated. Here, a laboratory scale multiphase flow rig was designed, fabricated, and assembled. Gas rates of 0.000113 m³/s and 0.000187 m³/s were imposed on a 1 mm single nozzle injector. Surface choking was implemented by setting the system to 15%, 25%, 50% and 100% opening. For each opening condition, transient pressure at four locations; corresponding to length-to-diameter ratios of 0.0, 18.3, 36.7, and 53.3, was recorded. Flow structure and regime transition are characterised by visual, photographic and slow-motion videos, recorded at each location. A transition from random peak-to-peak cyclic and periodic pressure oscillation, accompanied by pressure increase, is observed. Further, bubble size reduction characterised by low vorticity and turbulence is observed at 15% opening. It is concluded that surface choking must be complemented by knowledge of flow behaviour within the system. [Received: June 14, 2022; Accepted: March 20, 2023]

Keywords: gas-lift; multiphase flow; instability; fluid flow structure.

DOI: 10.1504/IJOGCT.2024.137879

International Journal of Oil, Gas and Coal Technology, 2024 Vol.35 No.3, pp.258 - 278

Received: 13 Jun 2022
Accepted: 20 Mar 2023
Published online: 05 Apr 2024 *

Title: Impact of surface choking on gas-lift stability and flow behaviour in oil producing wells

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