Biocidal compositions and methods of use

1. A synergistic composition comprising: 2,2-dibromo-3-nitrilopropionamide and tris(hydroxymethyl)-nitromethane in a weight ratio between 1:2.9 and 1:8.2.

2. A composition according to claim 1 further comprising one or more surfactants, ionic/nonionic polymers and scale, corrosion inhibitors, oxygen scavengers or additional biocides.

3. A method for controlling microorganisms in an aqueous or water containing system, the method comprising treating the system with an effective amount of a composition according to claim 1 .

4. A method according to claim 3 wherein the aqueous or water containing system is used or is present in oil and or gas production.

5. A method according to claim 4 wherein oil and gas production comprises injection and produced water, source water for waterflooding and hydraulic fracturing, pond water, holding tank water, functional fluids, drilling muds, completion and workover fluids, hydrotest fluids, stimulation fluids, packer fluids, fracturing fluids, oil and gas wells, separation, storage and transportation systems, oil and gas pipelines, oil and gas vessels, or fuel.

6. A method according to claim 3 wherein the aqueous or water containing system is cooling water, boiler water, pulp and paper mill water, other industrial process water, ballast water, wastewater, metalworking fluids, leather treatment fluids, paints and coatings, aqueous emulsions, latexes, adhesives, inks, pigment dispersions, personal care and household products, mineral slurries, caulks and adhesives, tape joint compounds, disinfectants, cleaners, or a system used therewith.