Comparison of the Performance of Commercial Flow Improvers in Wet Gas Horizontal Pipelines

There is a conspicuous absence of flow improver work for wet gas pipeline environments. The tests were carried out in a 44 m long, 10.16 cm diameter, industrial scale multiphase flow loop with a wide range of superficial liquid and gas velocities ranging from 0.03 to 0.1 m/s and 4 to 10 m/s, respectively. Oil with a viscosity of 2 cP and carbon dioxide were used as the liquid and gas phases, respectively. Two commercial oil soluble flow improvers (FI-1 and FI-2) were used for the tests. This paper discusses the comparison of the performance of these flow improvers in wet gas pipelines. FI-1 and FI-2 were able to decrease the pressure gradient in most of the cases. At the same superficial liquid velocity, the pressure gradient reduction increased with an increase in the superficial gas velocity. This was due to the increase in turbulence level at the liquid and gas interface. At superficial liquid and gas velocities of 0.1 and 10 m/s, FI-1 showed a maximum effectiveness of 13% with the reduction of pressure gradient from 86 to 75 Pa/m. Whereas, FI-2 achieved the maximum effectiveness of 25% as the pressure gradient decreased to 65 Pa/m at the same conditions. Flow improver-2 showed a better performance than Flow improver-1 at all conditions. The decrease in the height of the liquid film was accompanied with spread of the liquid film around the pipe circumference with the addition of both the flow improvers. The changes in the height of the liquid film were more significant with FI-2 than FI-1. At certain superficial gas velocities, it was seen that a transition in flow pattern occurred from wavy to smooth stratified flow with the addition of both the flow improves. This was because the flow was much smoother at the gas-liquid interface with flow improvers.