A Literature Review of Microbiological Issues Associated with Hydraulic Fracturing and Mitigation Strategies
Whilst it is well documented that Bacteria and Archaea can cause detrimental effects in oil reservoirs, such as reservoir plugging, souring, infrastructure corrosion, deterioration of hydrocarbon product quality and ultimately loss of hydrocarbon production, the same cannot be said for fractured shale reservoir wells, where the effects are not as well documented.
Microorganisms can be introduced into a fractured shale reservoir well in a number of different ways, namely through drilling muds, pre-fracturing fluids and impoundment waters. Furthermore, due to environmental concerns over the water disposal (either above or below ground), water shortages and availability of disposal wells, some of the flowback waters are recycled for use in the next well to be fractured.
There are various biocide treatment options available to the fracking operator, most of whom have a vast experience with biocides; however each treatment must be tailored to the shale play under operation, to achieve greatest biocidal efficacy. This provides minimal unwarranted detrimental effects, whilst minimising CAPEX and OPEX.
Optimal resource recovery strategies must rely on a thorough understanding of the complex biogeochemical, microbial, and physical interdependencies in these systems. (Wuchter, et al. 2013).
Overall, more research is required to fully understand what happens to microorganism populations during fracking operations.
This paper details a literature review of the published data relating to microbiological issues associated with hydraulic fracturing and mitigation strategies to minimise their effects.