An 18-year-old offshore pipeline system in Nigeria was found to have severe internal corrosion,
which was attributed to microbiologically influenced corrosion (MIC). MIC became the predominant
factor after the field matured and water cut increased. The inability to pig the majority of the system, the
difficulties associated with treating sump tanks that likely harbor large quantities of bacteria, and results
from pipeline intelligent tool inspections triggered an evaluation of potential treatment alternatives that
could provide enhanced solids and biofilm penetration. The operator and chemical supplier performed a
comprehensive system-wide bacterial characterization and biocide evaluation, which included testing in
the presence of solid and liquid samples obtained from the sumps and main lines. The inherent
bacterial populations were characterized by denaturing gradient gel electrophoresis and DNA
sequencing. Additionally, a dynamic closed flow loop was developed that recreated many of the
parameters in this system, including bacteria growth within pits, and allowed evaluation of more
effective biocides using planktonic and sessile kill studies. This work identified a synergistic twocomponent
product that: enhanced biofilm penetration, increased bacterial kill, and delayed biofilm
regrowth in laboratory studies. Field trials are in progress to evaluate the effectiveness of this new
product.
Keywords: microbiologically influenced corrosion (MIC), sulfate reducing bacteria, planktonic, sessile,
dynamic flow loop, denaturing gradient gel electrophoresis (DGGE), DNA sequencing