Abstract
Microbial issues have been a problem in many areas of the petroleum industry. Microorganisms can cause concerns with fouling, plugging and corrosion. One aspect of designing an effective integrity management program involves regular microbial monitoring and selection of the best chemistry for controlling microbes in a system. A variety of monitoring techniques are available that can be divided into two categories: on-site and off-site. Common practices for on-site bacterial monitoring include culture media bottles (i.e., serial dilution) and adenosine triphosphate (ATP) testing, both of which have advantages and limitations. Serial dilution bottles can detect specific categories of bacteria such as sulfate-reducing bacteria (SRB), but require 14 to 28 days for results. ATP testing is much faster, requiring only minutes to process samples, but is not specific in its detection of microbial types. The methods are also not as adept at identifying problematic archaea that may be present.
To provide additional tools for monitoring microbes, the oil field industry has begun using DNA detection for the presence of prokaryotes using methods such as quantitative polymerase chain reaction (qPCR), among others. DNA testing can provide improved sensitivity and specific information on the prokaryote of interest. Until recently, the technique was not been available as an on-site analysis. Microbial samples were sent to specific testing locations, causing long delays. The integrity of the samples can be compromised during the delay. This paper presents applications in oil field production, incorporating the stages for processing DNA such as stabilization, extraction and performing qPCR. The applications for the methods are useful for optimizing a microbial control program in addition to taking only a few days on-site to process as opposed to several weeks off-site. The novel on-site detection method is a useful tool in a broad range of applications for integrity management.
