Biocides protect wells from bacteria
Bacteria may be introduced into an oil or gas producing reservoir through a number of oil field processes such as drilling, hydrofracturing (fracing), water injection, and packer drill out. The common connection to all of these processes is water. Thus, the introduction of water into the reservoir can lead to microbiological contamination of the producing formation. Uncontrolled bacterial growth and activity from such contamination can lead to bacterial biofilm development and sulfide production potentially causing microbiological influenced corrosion (MIC), oil and gas souring, and loss of production. The culmination of all of these issues results in a loss of billions of euros annually within the petroleum industry. To mitigate these microbiological associated issues requires the application of a biocide where water is introduced into the oil and gas producing formations.
With vast proven petroleum reserves within shale formations, there is substantial growth in global unconventional shale oil and gas production. To achieve the necessary gas and oil production within these shale plays, hydrofracturing of the shale in the production zone is required. Hydrofracturing is achieved by introducing large volumes of water under very high pressure into the producing zone, fracturing the rock. With the introduction of water into the rock, the application of a biocide is required to mitigate the risk for microbiological growth and activity from possible contamination in the water.
Aiming at a sustainable and cost-efficient solution
Numerous public and governmental stakeholders are placing considerable pressure on the oil and gas production companies to reuse and recycle water in hydrofracturing operations. Furthermore, some unconventional gas plays are in areas that have little-to-no available surface water for performing hydrofracturing operations. Thus, working with and providing solutions to operators to increase their ability to recycle water and use brine flowback water would support efforts to reduce the need for natural water sources, resulting in a smaller ecological footprint for the oil and gas production companies.
Kemira was challenged with the task of increasing production for an operating company in the Marcellus shale region. To meet this challenge, Kemira tailored a friction reducer in order to obtain superior hydrofracturing performance. The challenge that Kemira faced was to develop a friction reducer that would consistently meet performance demands in high brine flowback waters, as well as be synergistic with a biocide that provides long-term well preservation against bacterial growth and activity. To achieve optimal hydrofracturing efficiency while reducing the customer’s total cost of operations, eliminating compatibility issues between the friction reducer and the biocide was critical.
Combination of chemistries
The combination of KemFlow A-4251 friction reducer and AMA®-324 biocide provided improved friction reduction performance as compared to the friction reducer alone. The friction reduction was maximized in produced and flowback waters and typical brine waters, reducing the need for surface fresh water. AMA-324 biocide provided excellent long-term bacterial control within the water used for hydrofracturing. Together, these products provide superior performance without the incompatibility issues seen in other friction reducer and biocide combinations, assuring continued quality production from the reservoir while maximizing the operating company’s assets.