Efficiency of Surfactant Batch Treatment in Horizontal Gas Well

The accumulation of liquid in horizontal gas wells is one of the major challenges faced by gas producers. This study investigates the efficacy of the use of surfactants when applied in a batch configuration without any form of downhole agitation. The experiments are performed in a 2-in ID facility with a test section that consists of a 64-ft long lateral section in a toe-up geometry, with -1° inclination, followed by a long 41-ft vertical section. The fluids used in the study are water as the liquid phase and compressed air as the gas phase. An anionic surfactant is used and injected into the heel of the well at varying concentrations.;For well startup conditions, the use of surfactant batch treatment is most effective for lower gas flow rates. Furthermore, the less the well is loaded, the more pronounced the effect of the surfactant is. The effect of increasing surfactant concentration is only eminent until the critical micelle concentration (CMC). No further improvement is observed at concentrations beyond CMC. Generally, surfactant batch treatment does not significantly improve well cleanup time.;During well production, surfactant batch treatment is most efficient in a low liquid and gas flow rate system. At increased liquid and gas flow rates, with increasing surfactant concentration, its use can be inefficient due to adverse effects caused by foam frictional pressure losses. For cases where the surfactant batch treatment is efficient, the effect increases with increasing concentration until CMC is reached. During severe slugging, surfactant batch treatment will eliminate the slug production phase and partially or fully eradicates the severe slugging depending on the severity of the slugs. Generally, no significant trends could be observed between the period of effectiveness and the concentration of surfactant.