Sulfate reducing bacteria (SRB) exist in many oilfield production systems. Their metabolic by-product, hydrogen sulfide (H2S), is corrosive and also combines with iron ions to form iron sulfide (FexSy) solids. The corrosive and plugging effects of these materials can severely impact operations and costs of a water injection system. Their control can present a significant challenge for the system operator.
This paper reviews the field performance of three different chemistries to control SRB, associated H2S, and FexSy solids. These chemistries include a mixed amine biocide, acrolein, and anthraquinone. Each chemical is applied to a specific part of the oilfield production system to effectively treat for biogenic sulfides. These locations include: at the producing wells, at the waterplant and downstream water injection system and a slop handling system. Each product was selected for its unique chemical properties that best resolved the specific field problems.
The results of this study indicate the following:
Periodic batch treatments of numerous artificial lift wells with a mixed amine biocide reduced the sulfides in the mixed produced fluids entering the waterplant inlet by 90%.
An acrolein batch treatment program reduced total suspended solids levels at the waterplant outlet by 87% and improved other water quality parameters in the downstream injection system.
Anthraquinone batch treatments into the slop handling system reduced sulfide levels by 95%.