Kemira Oyj : Preservative biocide extending the life of your hydraulically fractured well

​Reservoir souring, loss of conductivity, and microbiologically influenced corrosion (MIC) caused by sulfate-reducing bacteria (SRB) and acid-producing bacteria (APB) are well-documented problems occurring in unconventional gas plays after hydraulic fracturing operations.

The application of an appropriate biocides program is key for controlling microbiological activity within oil and gas systems.

Long term preservation of the oil and gas production zone as well as asset integrity of process equipment and pipelines become possible through the use of a preservative biocide.

Field trials and lab work demonstrate opportunity

Few biocides can provide long-term preservative control of an oil and gas system, but Kemira's AMA®-324 has demonstrated this unique ability both in the laboratory as well as through numerous field trials. Achieving long-term level preservation ultimately leads to a more successful production operation and extended asset life.

Traditional biocide applications including glutaraldehyde, glut-quat blends, THPS and DBPNA have been used in hydraulic fracturing applications. It is well established that the efficacy of glutaraldehyde is pH dependent. Its effectiveness is approximately 20 times faster at pH 8.5 than at pH 5. At pH 9, a reduction of viable APB and SRB by 3 logs or greater can be readily achieved. However, at a typical slickwater-frac-fluid pH of 6.5, glutaraldehyde exhibits a 10 times slower efficacy than at pH 9. At this same pH, AMA-324 provides better long-term preservation compared to glutaraldehyde.

While AMA-324 is not a quick-kill biocide, it has similar performance to glutaraldehyde after 24 and 48 hours at pH 6.5 when challenged with viable planktonic microorganisms. At pH 9 and 6.5, AMA-324's long-term performance was better than glutaraldehyde's against APB and SRB at the same active concentrations.

AMA-324 biocide has unique long-term biocidal properties against planktonic and sessile bacteria, which makes it an excellent biocide of choice for use in hydraulic fracturing applications for reservoir preservation. The benefits of using a proven long-term preservative biocide in hydraulic fracturing operations are significant to the well integrity. Kemira has the know-how and the resources to provide recommendations on the most effective use of biocides in oilfield operations.

Charting some of the results

At pH 6.5, after bacterial re-challenges, AMA-324 provided better long-term control of SRBs over 28 days. With significant re-challenges, SRB levels remained undetectable with AMA-324. Glutaraldehyde lost control over 28 days.

At pH 9, after bacterial re-challenges, AMA-324 provided better long-term control of SRB over 28 days. Glutaraldehyde had very good efficacy against SRB, achieving a 7-log reduction in 4 hours, but began to lose control over 28 days.

Kemira tailors its oil and gas industry service and offering for each individual customer need. If you're interested in learning more, you can reach Paula Henderson at paula.henderson[at]kemira.com.