Case Studies

Oil Fields

The Issue: Bacteria and Iron Sulfide Plugging

The Solution: Treatment with Sabre's DiKlor^SM service, using chlorine dioxide (ClO2) stimulation process

Background

A Denver-based oil and gas company operated a large oil and gas field in north central Utah. The producer had a history of bacteria and related iron sulfide problems.

Chlorine Dioxide Application Considerations

Oil and gas production was down to an average of 31 BOPD, with dark FeS streaks. The well had been treated with various conventional biocides. These conventional biocides were unable to eradicate the sulfide problem that had built up in the well and, therefore, it was necessary to find an alternative solution.

Chlorine Dioxide Treatment Approach

A complete study of the producer resulted in the recommended use of Sabre's DiKlor^SM service using chlorine dioxide treatment. DiKlor™ is staged with acid containing micellar solvent, corrosion inhibitor and iron chelant.

In conventional acid stimulation the acid solubilizes carbonate and iron sulfide which remains in solution as long as the pH remains below 2. Once the acid is spent and the formation fluid pH rises above 2, the iron sulfide re-precipitates, plugging the pore spaces.

The DiKlor^SM process enhances conventional acid stimulation by oxidizing the preferentially oil-wet hydrous ferric oxide which is then chelated by additives in the acid, and insoluble sulfide to water-soluble sulfate. Chlorine dioxide also has the ability to oxidize biomass and polymer damage.

1000 bbls of DiKlor™ staged with 15% HCl acid were pumped down the tubing after removing the pump. The well was shut in for one day after treatment before being brought back in production.

After treatment with Sabre's DiKlor™ the well was clean, producing yellow crude with no sign of FeS in the production. Gas production went from 76 MCF/D before the DiKlor^SM treatment to 188 MCF/D. Oil production went from 29 BOPD before treatment to 89 BOPD after the job.

Results

The DiKlor^SM treatment was successful. Over a 90 day period after the DiKlor^SM treatment the production revenue was approximately $150M, (an ROI of 301%), compared to revenue of about $50M if the field had elected not to complete DiKlor^SM treatment. The payback period for this field was 27 days. After 90 days the field was still producing at the higher rate.

The Science of Success

Unlike alternative technologies, chlorine dioxide is a true gas that is a relatively stable oxidant, reacting only with reduced compounds such as sulfides, phenols, and biomass. Additionally, chlorine dioxide kills both active and inactive bacteria, unlike conventional biocides. Chlorine dioxide has also been shown to kill bacterial spores with relatively low contact times, and bacteria cannot build resistance to chlorine dioxide. It is also a well-established EPA-registered biocide for use in the drinking water and food industries.

Sabre has over a decade of experience in the petroleum industry, with a perfect safety record to match. This is due to inherent functionality, where chemical precursors are vacuum fed to the point of reaction to form chlorine dioxide in the absence of dilution. This formation of chlorine dioxide independent of the water stream allows Sabre systems to operate with any fluid, including oil, water, emulsions, and slurries. This unique chlorine dioxide system has been patented by Sabre.

Chemical precursors on portable Sabre chlorine dioxide systems are separated by secondary steel containment to further protect from accidental mixing. Sabre has a unique understanding of the health and safety issues related to the use of chlorine dioxide due to its extensive experience with chlorine dioxide in both gas and solution phases.