Investigation of the Impact of Surfactant Concentration on Gas Well Deliquification

Abstract

This work investigates the effect of surfactant concentrations on gas well deliquification and quantify the incremental gas production rate. A base model was built to verify the possibility of liquid loading behavior using the Turner velocity criteria. Foam lift was enabled and the well flow path was defined including the micro-annular space between the coiled tubing and the tubing strings. Different Surfactant concentrations of 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 and 0.5mass percent were injected for an optimum concentration required to unload liquid from the gas well. Results reveals that the reservoir will deliver 13.315MMscf/day of gas across the completion into the wellbore when the pressure drawdown is maximum.The intersection of the inflow and outflow performance curves shows that the well was producing 2.09787 MMscf/day of gas which occurs where the Turner velocity criteria shows a potential issue (liquid loading). A gas production rate of 2.09787 MMscf/day was produced with no foam lift but with foam lift and 0.05mass% of surfactant injected, the well production rate increases from 2.09787 MMscf/day to 7.60823MMscf/day. The result shows that a surfactant mass percent of about 0.4% will maximize gas production from the well producing 7.71049MMscf/day. Results reveal that surfactant should not be injected at concentration above the critical micelles concentration (CMC) as it will lead to a significant increase in the frictional component of the fluid pressure loss due to the rheology of the foam.