Single Stranded DNA as a Source-Specific Hydrogeology Tracer

Chow, Justine; Rudulph, Jake; Weiner, Paul-Harvey

In the last decade, DNA has had some limited use in hydrogeology studies as particle tracers and taggants. Considering the recent improvements in Polymerase Chain Reaction (PCR) for DNA amplification, as well as DNA's unique properties as permutable biomaterial, it comes as a surprise that so few studies have fully utilized DNA's capacity as a multiple-source tracer. As such, we endeavored to examine DNA's utility in conditions where low-background tracing of multiple sources would be useful: hydraulic fracturing. We designed a single-stranded DNA tracer with an unusual secondary structure in order to confer durability in extreme conditions. In order to determine whether such a tracer could be used to detect potential surface water contamination from frac fluid, the tracer was exposed to UV radiation, simulating surface water or impoundment pond conditions. Experiments were conducted in proppant-free frac fluid and flowback water from West Virginia monitoring sites, as well as groundwater from Durham County, NC. Results indicate that the DNA tracer survives in detectable concentrations for up to and beyond 30 days in actual samples of frac fluid, flowback water, and groundwater. Future research will include examinations of tracer behavior and durability under high pressures, high temperatures, and high shear forces. We will also model and measure the adsorption and transport factors of the DNA tracer in order to parameterize application concentrations for low- and high-volume fracs. A groundwater field test is also planned: we will test detection and measure losses in known geological formations using spectrophotometry.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013