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Publication Number
US-11981862-B2
Publication Date
2024-05-14
Expiration Date
Abstract
The present disclosure relates to biocide compositions, formulations and methods for using formulations. In particular the present disclosure relates to biocide compositions and their use in effecting biocidal activity in subterranean oil and gas wells being drilled, completed, worked over or produced.
Core Innovation
The invention provides an aqueous, oxidizing biocide that generates hypobromous acid (HOBr) in situ by contacting a stabilized hypochlorous acid (HOCl) solution with a water-soluble bromide ion source. The stabilized hypochlorous acid solution is described as having a pH of at least 11 in embodiments, and the biocide contains a chlorine source, a stabilizer, a base, water, and the water-soluble bromide ion source.
The HOCl/bromide system is formulated to provide a chlorine residual with persistence after treatment, including chlorine residual for up to about 24 hours as described. The document states that this residual behavior supports reduction of bacteria and control of biofilms, and that the system provides effectiveness and biofilm penetration performance.
The biocide is applied in gas or oil wells and in well-associated fluids and equipment. The treatment includes preventing well souring, controlling bacterial growth, preventing microbiologically influenced corrosion (MIC), and controlling biofilms in the context of oilfield operations, including compatibility with gel-type and slickwater-type fracturing fluid additives and related components.
Claims Coverage
The independent claims cover three related process types using the same core oxidizing biocide chemistry and composition components while targeting different oilfield outcomes. Across the independent claims, the core inventive scheme is a stabilized hypochlorous acid (pH at least 11) plus a water-soluble bromide ion source, with specified weight-percentage ranges for chlorine source, stabilizer, base, bromide ion source, and water, and the well/fluids/equipment containing crosslinkers, gelling agents, friction reducers, or surfactants.
Stabilized hypochlorous acid (pH at least 11) plus water soluble bromide ion source oxidizing biocide
Treating the gas or oil well, well equipment, or frac fluid with an aqueous, oxidizing biocide comprising a stabilized hypochlorous acid solution having a pH of at least 11 and a water soluble bromide ion source.
Specified chlorine source, stabilizer, base, bromide ion source, and water weight-percentage ranges
Characterizing the aqueous, oxidizing biocide as containing about 1% by weight to about 20% by weight of a chlorine source, about 1% by weight to about 20% by weight of a stabilizer, about 5% by weight to about 10% by weight of a base, about 0.1% by weight to about 15% by weight of a water soluble bromide ion source, and about 35% by weight to about 92.9% by weight of water.
Oil or gas well contains crosslinkers, gelling agents, friction reducers, or surfactants
Wherein the oil or gas well contains one or more compositions, wherein the one or more compositions comprise one or more crosslinkers, gelling agents, friction reducers, or surfactants.
Preventing well souring in a gas or oil well
Preventing well souring in a gas or oil well comprising treating the gas or oil well with the aqueous, oxidizing biocide having the stabilized hypochlorous acid solution (pH of at least 11) and the water soluble bromide ion source.
Preventing microbiologically influenced corrosion on gas or oil well equipment
Preventing microbiologically influenced corrosion on gas or oil well equipment comprising treating the gas or oil well equipment with the aqueous, oxidizing biocide having the stabilized hypochlorous acid solution (pH of at least 11) and the water soluble bromide ion source.
Controlling bacterial growth in a frac fluid
Controlling bacterial growth in a frac fluid comprising treating the frac fluid with the aqueous, oxidizing biocide having the stabilized hypochlorous acid solution (pH of at least 11) and the water soluble bromide ion source, wherein the frac fluid contains one or more crosslinkers, gelling agents, friction reducers, or surfactants.
Across the independent claims, the main claim coverage is directed to processes that use an aqueous, oxidizing biocide having a stabilized hypochlorous acid solution (pH of at least 11) together with a water-soluble bromide ion source, with defined weight-percentage ranges for chlorine source, stabilizer, base, bromide ion source, and water. The processes are applied to prevent well souring, to prevent microbiologically influenced corrosion on well equipment, and to control bacterial growth in a frac fluid, with the relevant well, equipment, or frac fluid containing crosslinkers, gelling agents, friction reducers, or surfactants.
Stated Advantages
Effectiveness/“knockdown” of bacteria.
Biofilm penetration.
Long-lasting chlorine residual (including persistence for up to about 24 hours).
Compatibility with gel-type and slickwater-type fracturing fluid additives and friction reducers/surfactants/crosslinkers.
Reduced “sacrifice” compared with stabilized bromine.
Less aggressiveness toward additives.
Improved thermal stability for deep/high-temperature wells.
Minimal orthophosphate reversion compared with chlorine bleach when evaluated with phosphonate scale inhibitors (AMP/HEDP/PBTC).
Documented Applications
Preventing well souring in a gas or oil well by treating the well with the aqueous oxidizing biocide.
Preventing microbiologically influenced corrosion (MIC) on gas or oil well equipment by treating the equipment with the aqueous oxidizing biocide.
Controlling bacterial growth in a frac fluid by treating the frac fluid with the aqueous oxidizing biocide.
Use in well fluids including subterranean oil/gas wells, including fracturing/slickwater, gel fluids, drilling/completion/workover/produced water.
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