On the use of bleach soaks to control bacteria-mediated formation souring

Abstract

This a case study of a field test undertaken to establish whether the suppression of H 2S-producing bacteria near the water injector wellbore could be used to control progressive reservoir souring. Three produced water injectors were soaked with 16 m 3 of bleach for 20 h. The corresponding producers in the field pattern were monitored for produced H 2S for 40 days prior to and six months after the treatment took place. In addition, one untreated field pattern was monitored for H 2S production concurrently as a control. Because of the inconclusive results obtained, a bactericidal effect by the bleach could bot be established. Of the seventeen test producers monitored, six showed decreased H 2S production although the extent of these decreases was very small. No decreases in produced H 2S were detected in the control wells. Some chlorination of crude oil by bleach did take place under simulated reservoir conditions but only to a very small degree. No presence of halogenated hydrocarbon could be detected from produced oil exposed to the bleach treatments.