Aggressive moves counter SRB in flooded subsea pipeline

 Throughout this period, each of the laterals received biocide treatments on a regular rotation, and scavengers were applied. Corrosion inhibitors also continued to be injected into the gathering system at the producing platforms at the same rates used before Hurricane Ike.

 As the pH slowly increased to 7.3 from 6.5, concentrations of iron and manganese in the water samples gathered at Larose continued to slowly drop, suggesting corrosion was abating. Serial dilution studies throughout this period also showed microbial populations of SRB as below detectable limits; the microbiological processes were now being kept in check.

Continuing trend

  Through the rest of 2009 and early 2010, continued serial dilution and APS reductase studies show microbial populations have remained below detectable levels, even after biocide residuals approached zero. The pH of the water removed from the system continues to be in the range 7.1-7.2, and the concentration of dissolved has dropped to about 10 ppm. Excellent corrosion inhibitor residuals likewise indicate the system is properly treated. A spike in the amount of sand-quartz and iron particles removed during pigging runs in late 2009-early 2010 showed the need for a continuous pigging program to displace these denser particles through the gradual incline of the pipeline. These favorable results show the benefits of having implemented an aggressive chemical treatment and pigging program to regain control of internal corrosion mechanisms and thereby maintain pipeline integrity.