Tracer-based Quantification of Individual Frac Discharge in Single-well Multiple-frac Backflow: Sensitivity Study

Abstract

The use of artificial tracers as a tool for matrix and fracture (-network) characterization is examined in conjunction with a variety of geothermal-related fracturing operations in Germany, either chemical-based or plain-hydraulic, with or without proppants, both with short-term tracings (during and immediately after fracturing) and for long-term production monitoring, in sedimentary and crystalline formations in the N-German Basin, at the sites Horstberg and Groß Schönebeck. As an outcome of tracer test analysis for the latter site, a tool for the tracer-based quantification of individual frac discharge in single-well multiple-frac backflow and production can be derived, whose major advantage consists in using only stable conservative tracers, and in its independence from hydrogeological a priori knowledge. This tool can also be applied in unconventional hydrocarbon reservoir development and operation, where assessing the uniformity of multiple inflow zones is crucial to reservoir economics; complimentary use of reactive alongside with conservative tracers, with dual partitioning behavior for source and daughter species, enables to further determine the relevant hydrogeologic parameters of producing fracs or matrix ‘damage’ zones, independently of their productivity.