Water Shut Off in Gas Wells: Is there Scope for a Chemical Treatment?

Abstract

Abstract Water producing gas wells may suffer from liquid loading and get killed or their water production may exceed the capacity of the water handling facilities. Just closing off the water producing zone may be unacceptable if they have a large contribution to the gas production. A near well bore chemical treatment using a polymer solution is an option to reduce the water production and maintain the gas production. Once adsorbed to reservoir rock, the polymer may significantly reduce the relative permeability to water in the near well bore area. Hundreds of gas wells of the Nederlandse Aardolie Maatschappij (The Netherlands) suffer from water production. A simulation study using a radial single well model was carried out to look after the feasibility of a treatment. The study shows that a treatment based on reduction of the water relative permeability causes a choke effect: both the water and gas flow rates are reduced instead of only the water rate. Moreover, the benefits of a treatment are tempered because of a clean-up effect after injection of the chemicals. A reduction in the water/gas ratio by a factor 2 requires a reduction in the water relative permeability by at least a factor 10. A well which was killed due to liquid loading at a high water/gas ratio and with a high contribution to the gas production by the water producing interval is a suitable candidate for treatment. A treatment may also be considered for a well of which the water production exceeds the capacity of the water handling facilities. Provided that the flowing tubing head pressure can be significantly lowered, the loss of gas production from the water producing zone can be compensated by increased gas production from the other intervals.