Choosing the Right Biocide

Water is a part of oil and gas operations “tap to cap” from drilling new wells, operating pipelines and facilities, to final abandonment of wells and equipment. Effective operations and longevity of asset life rely on proper microbial control programs. Biocide use includes not only understanding the objectives of control, but also what influences the performance of the various biocides.

Each application has specific parameters to take into consideration, but there are some high-level considerations that can help narrow the choices. These are outlined below for hydraulic fracturing, well interventions, enhanced oil recovery (EOR) and pipeline integrity.

BiocideHydraulic FracturingCoiled Tubing/Well InterventionWaterflood EORPipeline Asset Integrity
Bronopol
Glutaraldehyde
Acrolein*
ADBAC, DDAC (Quaternary Amines)*
THPS++++
Diamine Acetates*
CMIT, MIT
TTPC++++
DBNPA**
Dazomet++
THMN, CTAC, DMO
Bleach, Chlorine Dioxide, Peracetic Acid, Ozone****

* These biocides are typically used for clean outs or in conjunction with another biocide for total control.
+ These biocides may need higher dosages depending on conditions including salinity and amount of iron. Always check for biocide compatibility with fluids and equipment.

Application Objectives

Hydraulic Fracturing

Maintain fluid stability on surface and prevent contamination of the reservoir.
Biocide Selection:

  • Effective kill of free floating microbes (planktonic)
  • Compatible with fracturing fluids, fracturing equipment and recycled source waters
  • Compatible with reservoir environment i.e. temperature, scaling ions, H2S, salinity and iron
  • Will not film out on reservoir surfaces reducing conductivity
  • Will not foam during operations

Coiled Tubing Operations / Well Intervention

Protect equipment from microbial influenced corrosion (MIC) by preventing biofilm formation. This ensures longer run life.
Biocide Selection:

  • Effective kill of free floating microbes (planktonic microbes)
  • Compatible with well intervention fluids and equipment
  • Surface active biocides work well for cleaning and post job protection during asset storage
  • Biofilm penetration may be required for previously contaminated equipment

Waterflood EOR

Prevent contamination of the reservoir. Maintain effective injection pressures and volumes. Prevent biofilms in complex water storage
and distribution systems.

Biocide Selection:

  • Effective kill of free floating microbes (planktonic microbes)
  • Compatible with injection waters and reservoir environment
  • Long lasting (persistent)
  • Cleaning biocides may be required for contaminated injectors or water storage/distribution systems

Pipeline & Asset Integrity

Prevent MIC and downstream contamination (e.g., facility assets, injection wells).

Biocide Selection:

  • Surface active biocides and combinations thereof for total control
  • Compatible with production chemicals
  • Biocide choice will depend on fluid composition (e.g., oil, gas, water and combinations thereof)
BiocideCharacteristics
BronopolMultiple modes of action, primarily causing cell leakage. Non-ionic and works in a wide range of pH 2-9. Isn’t
susceptible to salinity issues or higher total suspended solids (TSS).
GlutaraldehydeCrosslinks molecules in membranes, disrupting membrane function. Non-ionic. More effective at higher pH.
AcroleinCrosslinks molecules in membranes, disrupting membrane function. Effective for biofilm removal. Can be used in
squeeze applications but only where completely closed system is utilized. Use extreme caution in handling.
ADBAC, DDAC
(Quaternary Amines)
Penetrates cell membranes, causing cell leakage. Surfactant. Provides filming protection. Decreased effectiveness in
increasing brine concentration. Potential for foaming and emulsion issues.
THPSCleaves sulfur-to-sulfur bonds, disrupting cell membrane functions. Filming characteristics. Is an iron chelator and
biocide efficacy will decrease as iron increases.
Diamine AcetatesPenetrates cell membranes, causing cell leakage. Surfactant. Provides filming protection. Decreased effectiveness in
increasing brine concentration. Potential for foaming and emulsion issues.
CMIT, MITInhibits metabolic activity. Also known as isothiazolinone. Known sensitizer, use caution when handling.
TTPCPenetrates cell membranes, causing cell leakage. Surfactant. Provides filming protection. Decreased effectiveness in
increasing brine concentration. Potential for foaming and emulsion issues.
DBNPAFast-acting disruption of cell membranes. Often called the “organic oxidizer.”
DazometInhibits metabolic activity. May interact with heavy metals, iron and H2S, creating solids.
THMN, CTAC, DMOThese are persistent biocides that have long-term control. Known to be formaldehyde releasers, which is their primary
mode of action.
Bleach, Chlorine Dioxide,
Peracetic Acid, Ozone
Oxidizes molecules in cell membranes, causing membrane degradation. Fast acting. Oxidizers vary in their reactivity
with inorganic molecules, so dosages will vary depending on selection.

Summary

For any biocide application, testing is recommended prior to use to ensure compatibility with all system components and efficacy in the environment for the duration that control is required. Sometimes, combinations of biocides are required and can provide a more economical choice. Talk to our team at OSP for support in testing, selection and application best practices.

The information contained herein is based on data available to us, and is believed to be accurate. No guarantee or warranty is provided or implied by the company in this respect. Since the use of this product is within the exclusive control of the user, it is the user’s responsibility to determine the conditions of safe use. Such conditions must comply with all governmental regulations.