Abstract
Microorganisms present multiple challenges in oilfield systems such as microbiologically influenced corrosion (MIC), reservoir souring, and biofouling. The misapplication of biocides can lead to significant issues in field operations, including resistance and/or lack of susceptibility of the microbial population to biocide treatment. The selection of chemistries to minimize microbial risk has traditionally relied on culture-based methods such as serial dilution to determine biocide efficacy. However, the diversity of microbes and the unique conditions found in each oil and gas asset make it very challenging to obtain reliable results through growth assays in culture media. Field-based molecular microbial enumeration technologies, such as the quantification of intracellular adenosine triphosphate (cATP) and adenosine monophosphate (cAMP) have advanced significantly in the past 5 years and are often relied upon to determine microbial risks in production systems. Additionally, laboratory based methods such as Flow Cytometry, quantitative-polymerase-chain-reaction (qPCR), and next-generation DNA sequencing (NGS) have begun to shed light on the complex microbial populations inhabiting these production systems. Using this multifaceted approach, we have begun to further understand the effects of prolonged treatment with water quality chemistries such as solids control products and the negative effects it can have on a microbial control strategy. In this study, we look at a production system where the application of low-dosage solids control chemistries caused the microbes to become dormant and thus more resistant to biocide treatments which increased the risk of MIC related failures. Furthermore, treatment of these microbes with other solids control chemistries and biocides have revealed a number other of resistance mechanisms suggesting these microbes utilize multiple strategies for survival which may complicate remediation efforts.
