Abstract
A novel inhibitor squeeze program has been applied to control SRB (sulfate-reducing bacteria) and microbially-influenced corrosion (MIC) in the injection water supply wells of a sweet, Arab Superlight oilfield located in Central Saudi Arabia. The treatment is based on a biocide-enhanced corrosion inhibitor squeeze, spear-headed by concentrated biocide, and is unique in attempting to affect control of SRB and MIC from within the aquifer supplying injection water to the system. Applications of the treatment were intensively monitored in the field to assess the rate of return of the chemical, and their effects on microbial populations in the wells. Non-surface active biocide components were produced back in short, concentrated slugs comparable to shock doses in pipeline treatment programs, providing effective short-term control of SRB activity in the water supply wells. Regrowth, however, resumes once the chemicals are flushed from the wells during normal production, limiting the effective life of the biocide treatment in these wells to 2–3 weeks. Amines are extensively adsorbed on clay minerals, and are produced back at low concentrations for extended periods of time. The data provide insight into the range of rock-chemical interactions that can occur when squeezing multi-component oilfield chemicals into a sandstone aquifer containing significant quantities of clay minerals. The investigation highlights the importance of effective microbiological control during initial drilling and completion operations, and the difficulty in treating established microbial populations in porous media with biocides developed primarily for pipeline systems.
