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Harmful Bacteria in the Oilfield

Oilfield operators have known about microbiologically influenced corrosion since the 1920s and the leading role of sulfate reducing bacteria (SRBs). These ubiquitous bacteria live in oxygen-excluding habitats such as pond and stream sediments. Once they enter a well they consume iron from the steel in pumps, pump rods, downhole tubing, and surface equipment. This microbiologically influenced corrosion (MIC) can cause catastrophic failures in as little as a few weeks after well completion. Unfortunately, today's standard microbiological methods typically require 4-6 weeks for turnaround. This long delay allows harmful bacteria to establish themselves and grow quickly.

Pulling and replacing corroded steel has very high costs. And production lost during repairs compounds the costs.

Ubiquitous sign in oil and gas fields, thanks to bacteria.

Research suggests that SRBs and other harmful organisms originate from outside of hydrocarbon reservoir formations. Well drilling and completion—especially fracing—use enormous volumes of water obtained from surface sources. Stream and pond sediments provide the natural habitat for organisms that can thrive in deep, oxygen-depleted porous rock containing hydrocarbon nutrients and high sulfate levels.

Tanker trucks carrying chemicals and millions of gallons of surface water for a frac completion.

Bacteria-caused pit corrosion in oilfield tubing resulting in catastrophic failure. This also occurs in transport pipelines and tanks.

SRBs also generate large volumes of hydrogen sulfide (H2S), a gas at least 20 times more toxic than carbon monoxide. H2S creates a serious hazard to workers, sours the hydrocarbon reservoir, and accelerates corrosion by direct attack on steel. Souring greatly affects oil and gas value and may require reduction before being accepted for transport or storage.

Effective SRB management requires large amounts of  biocide chemicals. But unguided precautionary use of expensive biocides may prove unnecessary or ineffective against the offending organisms. Inappropriate biocide use also tends to select for bacterial strains that become resistant to a biocide.

A frac manifold for well completion in shale.

Ideally, screening the source water used in drilling and completion would provide the most effective intervention by preventing harmful organisms from entering a well. And the same solution for near-real-time organism detection, identification, and abundance would also apply to optimum biocide management in producing wells. These measures should substantially reduce the operator's total cost of ownership over time.

Saigene's automated processor and SHA kits fulfill these needs. They represent a potential major advance in prevention, assessing biocide effectiveness, monitoring wells, and helping to devise the most effective long-term treatment plan.

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