Liquid loading has been a problem for natural gas wells for several decades. With gas fields becoming mature and gas production rates dropping below the critical rate, deliquification becomes more and more critical for continuous productivity and profitability of gas wells.
Current methods for solving liquid loading in the wellbore include plunger lift, velocity string, surfactant, foam, well cycling, pumps, compression, swabbing and gas lift. All these methods need to lift the liquid up to surface, which increases the operating cost, onshore and offshore. A better completion method has been developed to separate and reinject the liquid into the reservoir formation.
The new completion method – wellbore separation and reinjection through vertical well or horizontal well – depends on reservoir permeability, reservoir pressure, formation thickness, liquid production rate and geology. Through numerical reservoir simulation study, these parameters have been quantified and optimal completion has been developed for particular reservoirs based on gas recovery. Effect of liquid loading on gas productivity has also been investigated in two aspects: backup pressure and near-wellbore-liquid blocking. The new completion methods can increase gas recovery, prevent scale problem in the wellbore and surface pipeline, and avoid the liquid lifting and processing. It is an effective, economical, and environment friendly technology for natural gas wells.