Biocides are commonly used in upstream O&G extraction and are predominantly introduced to control unwanted biofouling in injection and production systems. Semi-regular, high-concentration batch injection of biocide products into oilfield reservoirs is not uncommon and has been shown to reduce microbial activity around the near wellbore of the injector. Some studies and pilot field trials have also demonstrated reduced souring rates under low concentration, continuous biocide injection. Key challenges to successful biocide application in the contaminated subsurface include ensuring significantly high biocidal concentrations at the required contact times, when in the presence of SRP, and biocide stability under downhole conditions. Sulfate removal from the injection water is both the most reliable and the most expensive option in reducing souring propensity. Traditionally used to reduce the formation of inorganic scale, sulfate removal uses nanofiltration membrane technology to reduce the overall sulfate concentration to between 10 and 30 mg l –1 . This significant decrease in concentration limits the overall capacity of microbial sulfate reduction. Some studies have also demonstrated that low- salinity water injection into oilfields may have an enhanced oil recovery (EOR) effect. Beyond souring As the Energy sector transitions to ‘cleaner’ initiatives, many issues associated with deleterious microbiology are likely to remain. However, using our existing understanding of oilfield microbiology can guide the exploitation of both new and existing subsurface environments. For example, depleted oilfield reservoirs or saline aquifers, used for the long-term storage of gases such as carbon dioxide (CO 2 ) or hydrogen (H 2 ), could prove susceptible to microbial fouling, significantly reducing the success of operations. However, through further development of microbial modelling and laboratory-based simulation studies, linked with the latest microbial community analysis techniques, we can determine which assets are most suitable for processes such as carbon capture and storage (CCS) and ultimately de-risk the future of carbon sequestration for decades to come. Biography Matt has worked at Rawwater since 2010, specialising in understanding and managing problems associated with microbial biofouling in the Energy industry. His main expertise lies in souring forecasting modelling and extreme environment testing. Alongside his industrial role, Matt is the Industry Liaison Officer for the Geomicrobiology Network and is undertaking a part-time PhD in Environmental Geochemistry and Geomicrobiology at the University of Manchester.
Matt Streets Head of Division and Senior Research Scientist Rawwater Engineering Company Limited, Culcheth Enterprise Centre, Withington Avenue,
Culcheth, Warrington, Cheshire WA3 4JE, UK
matt.streets@rawwater.com matt-streets-9911a315a
19 Microbiology Today May 2023 | microbiologysociety.org
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