October 1996
2nd Arabian Corrosion Conference
Kuwait
Conference Paper
Evaluation of Microbially Influenced Corrosion Risks and Control Strategies in Seawater and Produced Water Injection Systems, Kuwait
Injection of seawater and produced (effluent) water for secondary oil recovery can encourage the growth of bacteria, particularly in biofilms on pipewall surfaces. One particular problem in water injection systems is the uncontrolled growth of sulphate-reducing bacteria (SRB) which leads to increased corrosion of process plant. Injection water sources in Kuwait range from brackish water (Total Dissolved Solids = 4,000 mg/l) through seawater (TDS = 30,000 mg/l) to highly saline brines (TDS = 200.000 mg/l). In addition, some of these water sources are highly sulphide sour and may require treatment to prevent scaling, corrosion or iron sulphide precipitation.
Studies were undertaken to evaluate the relative risks of microbially influenced corrosion in a range of Kuwait water sources, using a combination of field sampling and laboratory biofouling trials. Bacteria isolated from the field surveys were used to evaluate remedial treatments such as chlorine, chemical biocides and mechanical removal. Recirculating biofouling loops were set up with the appropriate site water, and inoculated with the bacteria from the system so that an active biofilm was set up on the small steel studs. These biofouled studs were treated with proprietary anti-bacterial products under various dose regimes, in order to select the most appropriate control regime for particular water chemistries and process options.
