Abstract
Gas-lift is one of the artificial methods in which gas is injected down the production casing–tubing annulus and enters the production tubing through a number of gas-lift valves. During the production of a gas-lift well, the injected compressed gas might cause changes in pressure, temperature as well as fluid composition. When the temperature of the oil falls below the wax appearance temperature, it leads to the formation of organic wax deposits. Wax precipitation in well tubing and processing equipment might lead to dramatic reduction in production, equipment failures, loss of storage and transport capacity, and loss of efficiency. This paper presents a detailed study of wax formation in a gas-lift well. Taking into account changes in the oil component composition during gas injection, the depth of wax formation has been determined by applying a highly accurate developed algorithm. The optimal operating regime of the gas-lift well has been determined using a compositional multiphase model.
Highlights
Gas-lift is a simple reliable artificial lift method that is commonly used in offshore oil field development (Fleyfel et al 2004; White et al 2018; Shedid and Yakoot 2016; Feder 2019)
The novelty of this paper is to provide a detailed study of the wax formation process in a gas-lift well
It was perceived that with an increase in water cut to the phase inversion point, an increase in the viscosity of the oil–water emulsion is observed, which leads to a decrease in the liquid flow rate of the gas-lift well
Summary
Gas-lift is a simple reliable artificial lift method that is commonly used in offshore oil field development (Fleyfel et al 2004; White et al 2018; Shedid and Yakoot 2016; Feder 2019). Conventional models of continuous gaslift processes applied a black-oil treatment of the hydrocarbon fluids (Carroll et al 1990; Schou et al 1991; Mydland et al 2020; Du et al 2018; Coutinho et al 2017; Zhao et al 2017) Those models are unreliable due to the multiphase flow regime of the oil and gas mixture and the pressure drop in the wellbore is highly composition dependent. The well-known methods to study the wax formation process during the production in a gas-lift well have overlooked the effects of the compressed injected gas on the WAT subsequently it leads to a significant error and creates many operational hazards for the development of the oil field. The optimal operating regime of a gas-lift well (flow rate and the injection pressure of produced gas) has been determined using the compositional multiphase model
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