Bacteria Control Agents
Types of Bacteria
Bacteria can cause problems in oil-field operations. Even though these bacteria are extremely small (1 to 3 microns), their sheer numbers can cause plugging problems in injection wells.
Generally, the worst problems result from the by-products or chemical processes of certain organisms. Some of these problematic bacteria are sulfate-reducing bacteria, slime-forming bacteria, and iron bacteria.
Sulfate-reducing Bacteria The bacterium causing the greatest concern to oil producers is the sulfate-reducing organism. This bacterium, an anaerobic organism, needs an oxygen-free atmosphere in order to spread. Under anaerobic conditions, it can produce H2S. This gas can then corrode downhole tubulars, producing iron sulfide (FeS), which is insoluble in water and acts as a plugging agent.
Slime-forming Bacteria Other troublesome bacteria are the slime-forming types. Under aerobic conditions, they may produce large slime masses that cause severe plugging problems. These bacteria are usually found where fresh or surface water comes in contact with produced water.
Iron Bacteria A very common bacterium that can cause problems is the iron bacterium. This aerobic bacterium has the ability to oxidize water-soluble ferrous ion to a water-insoluble ferric ion in its metabolic processes. Iron bacteria can cause plugging of source well, filters, and surface lines.
Bactericides
Many chemicals can be used to control the growth of microorganisms. The most common term for chemical agents designed to kill and inhibit the growth of bacteria is bactericide or biocide. Use of a bactericide can reduce or eliminate the severe problem associated with bacteria.
Many bactericides, both cationic and nonionic materials, can be used in acidizing solutions. These chemicals are effective at killing bacteria in concentrations from 1 to 2 
.
