Effect of long term application of tetrakis(hydroxymethyl)phosphonium sulfate (THPS) in a light oil-producing oilfield

Abstract

Samples of (I) produced waters, (II) central processing facility (CPF) waters and (III) pipeline solids were collected from a light oil-producing field. The biocide, tetrakis(hydroxymethyl)phosphonium sulfate (THPS) was routinely used in the CPF. Samples monitoring indicated that THPS was effective in microbial control but also increased concentrations of sulfate and phosphate in transitioning from Type I to Type II waters. Type II waters had high concentrations (up to 60 mM) of acetate but low most probable numbers (MPNs) of acid-producing and sulfate-reducing bacteria, indicating the presence of active biocide, as high MPNs were found in Type I waters. Solids had high phosphate and high MPNs, indicating that THPS was inactive. Solids had oil and an anaerobic community dominated by Acetobacterium, which may contribute to conversion of oil to acetate. The presence of THPS prevented the use of this acetate in Type II waters, where it accumulated to unusually high concentrations.

Keywords:

• Biocide
• THPS
• microbiologically influenced corrosion
• sulfate
• phosphate
• microbiological community

Acknowledgements

This work was supported by an NSERC Industrial Research Chair in Petroleum Microbiology Award to GV, as well as by BP America Production Co., Baker Hughes Canada, Computer Modeling Group Limited, ConocoPhillips Company, Dow Microbial Control, Enbridge, Enerplus Corporation, Intertek, Oil Search Limited, Shell Global Solutions International, Suncor Energy Inc., Yara Norge AS and Alberta Innovates.

Disclosure statement

No potential conflict of interest was reported by the authors.