Abstract
In oilfield systems, the detection of live bacteria is necessary to evaluate the potential for microbially influenced corrosion (MIC), biogenic souring and to evaluate the effectiveness of biocide treatment programs. Biocide is often over-or under-dosed in the absence of timely data to determine viable bacterial concentration in the target system. Serial dilution into bacterial culture media, the most common method to enumerate viable oilfield bacteria, takes up to 4 weeks to obtain results for the slow-growing sulfate-reducing bacteria (SRB). Direct microscopy is an alternative method which is rapid but does not distinguish live from dead bacteria. Uncontrolled growth and activity of SRB in oilfield systems can create safety, environmental, and operational problems such as MIC, solids production, and biogenic hydrogen sulfide (H2S) generation. A method for the rapid enumeration of living bacteria would allow biocide treatments to be quickly evaluated and adjusted, maximizing bacterial control and minimizing the environmental impact from the chemical application, resulting in rapid optimization of chemical usage. A novel, field and user-friendly method is presented for the rapid enumeration of live SRB. This method is based on the rehydration of dried nutrients with system water and can quantify SRB in 1 to 7 days. Data from laboratory and field applications for validation of the enumeration method are presented.
