The Role of Rare Earth Elements As Naturally Occurring Tracers for Water Migration in Unconventional Oil and Gas Development.

The role of rare earth elements as naturally occurring tracers for water migration in unconventional oil and gas development

 Athanasios Karamalidis^1,2, Clinton Noack^1,2, David Dzombak²

¹National Energy Technology Laboratory-Regional University Alliance, Pittsburgh, PA

²Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA

The combination of horizontal drilling and high-volume hydraulic fracturing has led to a rapid expansion of oil and gas exploration and development of unconventional reserves such as tight-gas sands, unmineable coal seams, and organic-rich shales. Concern about potential impacts on groundwater resources has stimulated research on new approaches for monitoring aquifers and for early detection of brine and gas that may migrate into aquifers from shale gas development.  Monitoring programs will rely on multiple tools to identify presence and concentrations of brine and gas migration into aquifers. 

A significant body of research is growing that focuses on the capabilities of naturally occurring, chemical tracers to provide insight into the fate and transport of injected and native fluids during extraction of oil and gas from unconventional reservoirs. The rare earth elements (REE; Sc, Y, and the lanthanides) are attractive for such applications owing to their consistent and predictable reactivities; fluids originating from various strata may be distinguishable on the basis of the dissolved REE concentrations and their inter-element relationships.

In this talk we will present results from analyses of cores and outcrop samples of the Marcellus Shale, focusing on the occurrence of the REE and their mineralogy in the shale. These results form the basis for further investigation of REE mobility upon hydraulic fracturing of the shale.