Investigation of gas composition on production performance of J-shaped gas-lift well

Abstract

The J-shaped gas-lift well showed complex dynamic phenomena. The downward inclination of the J-shaped well introduces periodic waves over time as a result of mixing gas and liquid. This behavior introduces periodic fluctuations of the superficial gas and liquid velocities along tubing. The velocity fluctuation is due to the accumulation of liquid in the heel of the inclined section of J-shaped well and the development of reservoir gas pressure to overcome the accumulated liquid column making the J-shaped gas-lift well to be prone to production under slugging regime. The investigation here is addressing two aspects with the objective to optimize the gas-lift performance. The first addresses the production behavior and the mechanism that leads to development of slugging regime in the J-shaped well. Secondly it addresses the effect of the gas composition of the gas-lift on the production performance. Different gas-lift gas composition causes the gas and liquid compositions to change with the pressure and temperature profile in the production tubing. Gas-lift contains C1 as a major component. The work here shows that a fraction of 0.15 nC5 combined with C1 gives highest oil production rates. In the contrary, high content of 0.20 iC4 with C1 give lowest oil rates. This outcome would assist in designing optimum gas-lift injection system.