Flow Instabilities in Gas-Lift Wells with Water Coning

Abstract

Linear and nonlinear stability analysis of flow instabilities gas-lift wells with water coning was performed in this paper. A new gas-lift stability criterion, which takes into account water coning, was developed. The criterion was used to analyze flow instability in an offshore gas-lift well. The effect of the water-coning performance on the conditions of the onset of instabilities was investigated. The nonlinear analysis showed that one of the most important instability modes in gas-lift wells is associated with two types of density waves: liquid and water holdup waves. Flow instability in gas-lift wells may result in that the maximum instantaneous liquid flow rate may be several times larger the average liquid flow rate for long periods of time (tens of minutes) in one cycle of oscillation. It was shown that water coning has a strong destabilizing effect on the flow in gas lift wells with a large vertical distance between the injection point and perforations. In some cases heading in such wells cannot be eliminated by increasing the wellhead pressure. One of the most important instability modes in gas-lift wells is associated with two types of density waves: liquid and water holdup waves.

Effectively optimizing production of horizontal wells in homogeneous oil reservoirs

“…The water and gas move up and down respectively towards the perforations of the well, while displacing the oil along its path and after the breakthrough time elapses, insurgence of water and or gas will be experienced. At this point, factors such as liquid production rate (Lozada et al, 2011) or withdrawal rate, ratio of water-to-oil mobility, ratio of vertical-to-horizontal permeability, distance from the wellbore to oil-water contact, productive length of the wellbore, and both the size and shape of drainage area will determine the water cut increment (Permadi andJayadi, 2010, Yang andWattenbarger, 1991). Water cresting is known to have an adverse effect in oil producing reservoirs (Weijun et al, 2014) and could lead to the early shutting-in of producing wells.…”