Deliquifkation of Low-Productivity Natural Gas Wells with In Situ Generated Foams and Heat

摘要

Deliquification with chemical foamers has proved a successful and economic technique to unload the liquids from mature natural gas wells; however, no gases are available to create foams in the low-productivity gas wells. In this work, in situ generated foams (ISGF) were developed with the gas and heat produced by the reaction of ammonium chloride and sodium nitrite in the presence of acetic acid as a catalyst, with the mixture of sodium dodecyl sulfate and cocamidopropyl hydroxyl sulfobetaine as the foamer. The molar ratio of reactants to catalyst, and the specifies of ammonium salt were optimized based on the foamability and stability of the foams. The volume of gas and the amount of heat were measured from the optimized gas- and heat-generated system. The morphology of the ISGF foams was found to be more uniform than their conventional counterpart, and these foams exhibited superior foaming at high temperature and high salinity. The optimized formulation was scaled up and applied in two typical low-productivity gas wells, and significant increment in gas production and decline in water production were found. The ISGF foams not only offer a choice to unload liquids from mature gas wells by providing gas to create foams and to offer heat to dissolve organic pollutants but also provide candidature techniques for unconventional gas wells to prolong life spans.