Mitigating Sulfidogenesis With Simultaneous Perchlorate and Nitrate Treatments

Area of Science:

• Environmental Microbiology
• Petroleum Geochemistry
• Biogeochemical Processes

Background:

• Sulfide biogenesis (souring) in oil reservoirs is a significant operational challenge.
• Current nitrate treatments for souring inhibition are often inconsistent and require high concentrations.
• Perchlorate shows promise as a more potent souring inhibitor in laboratory settings.

Purpose of the Study:

• To investigate the potential synergy between nitrate and perchlorate for oil reservoir souring inhibition in a dynamic system.
• To evaluate the effectiveness of combined perchlorate and nitrate treatments compared to individual treatments.

Main Methods:

• Triplicate glass columns packed with marine sediment were used to simulate reservoir conditions.
• Columns were flushed with sulfate-containing media and subjected to inhibitor treatments: perchlorate, nitrate, or combined perchlorate and nitrate.
• Geochemical parameters and microbial community dynamics were monitored throughout the experiment.

Main Results:

• All inhibitor treatments reduced sulfide production compared to the untreated control.
• The combined perchlorate and nitrate treatment showed additive, not synergistic, effects compared to individual treatments.
• Microbial community analysis revealed perchlorate as the dominant factor influencing community structure in the mixed treatment.

Conclusions:

• Concurrent nitrate and perchlorate treatment is not more effective than perchlorate alone for oil reservoir souring inhibition.
• Perchlorate treatment alone is more effective than nitrate treatment alone.
• Treatment decisions for reservoir souring should consider the relative effectiveness and economic factors of perchlorate versus nitrate.