Rising demand for flowback technologies that reduce the uncertainties associated with horizontal shale wells is also leading to the creation of more hydrocarbon and water tracers. Used to identify the source of production in a well, these chemical-based tracers may play an important role in the shale industry’s effort to come up with more cost-effective fracture designs.

The tracers are deployed downhole along with the sand or proppant material that is being pumped into the fractures. The chemical compounds are tailored to flow with oil or the water produced in oil and gas wells. Unlike radioactive tracers, which require a well to be shut in for a log run, chemical tracers are sampled at the wellhead in continuous intervals during the flowback and production periods and then analyzed in a laboratory.

For production analysis, the concentration of the tracers that flows back to the surface over time can determine the effectiveness of each stage. All things being equal, on a 30-stage well, the tracers from each stage would represent between 3% and 4% of the total concentration of tracer material sent downhole. But in reality, that is hardly ever the case.

“We see cases where stages are producing 10%, 12%, or 14%, and others where there is hardly any—1% or less,” said Claudio Ramos, a region engineering adviser with CoreLabs’ ProTechnics diagnostic service.

ProTechnics began the year with 10 oil tracers, 10 gas tracers, and 14 water tracers. This fall, those numbers increased to 28, 15, and 29, respectively. By early next year, the company plans to have 34 tracers for oil and water, and, hopefully, more gas tracers as well.