Walter R. Dill

Iron Control in West Texas Sour-Gas Wells Provides Sustained Production Increases

Permian Basin operators have recorded sustained production increases in oil wells by preventing precipitation of iron sulfide and other sulfur-containing species. This improvement has resulted largely from cleaning out tubing before acidizing and from preventing the precipitation of ferrous sulfide and the formation of elemental sulfur by simultaneous use of iron chelants and sulfide-control agents. Previously used methods gave only temporary production increases that terminated when iron dissolved by the stimulation acid reprecipitated in the pay zone and damage the formation after the stimulation acid was spent. This paper describes a method to optimize iron sulfide control, methods to minimize reprecipitation, and case histories from the Permian Basin that show improved methods to control iron in sour-well environments.