FROM NANOFLUIDICS TO BASIN-SCALE FLOW IN SHALE: TRACER INVESTIGATIONS

Understanding the processes of fluid flow and mass transport in shale is of great importance to the development of unconventional hydrocarbon reservoirs and deep geologic repositories for waste disposal. Tracer techniques provide a useful tool for studying such processes. Shale is characterized by the predominant presence of nanometer-sized pores and extremely low permeability. Chemical species in nano-confinement behave differently from those in a bulk system. This confinement effect enhances chemical separations and isotope fractionations in a shale formation, leading to a unique set of tracer signatures that can be used to delineate flow regimes, trace fluid sources and quantify the rates of related physical/chemical processes. These signatures may help to detect structural defects and fast flow pathways in a shale cap rock. They can potentially be used for the post-closure monitoring of a geologic repository or the evaluation of a possible contamination of a shallow water aquifer by a shale oil/gas extraction.