Post-treatment horizontal hydraulic fracture modeling with integrated chemical tracer analysis, a case study

Abstract

As early as the 1950s, the need to track water in various applications, including stream water, sanitary systems, ground water, and oil field water flooding, resulted in the development of chemical tracer technologies. While the utilization of tracer technologies to track water during reservoir development is mature, the use of chemical tracers in unconventional hydraulic fracturing operations is relatively new. With the increasing use of chemical tracers in unconventional settings, questions related to the proper execution, interpretation, and integration of chemical tracer tests arise. The first part of this research discusses the design and analysis of a tracer study conducted in a section of the Wattenberg Field, Colorado. The results of the tracer study showed that the preferential direction of cross-well tracer flow during hydraulic fracturing reflected the order of completion rather than the geology. However, large geologic features, such as a faulted graben, can facilitate cross-well transport of water-based chemical tracers during fracturing. Minor faults between wells can facilitate cross-well transport of oil-based chemical tracers during production. Furthermore, the percentage of recovered tracers from different intervals along the wellbore varies, which can reflect the contribution of that interval to the net production. Based on the analysis, suggestions on how to conduct a tracer study to obtain high-quality data are provided. The second part of this research shows how the results of the tracer study can be integrated into a post-treatment hydraulic fracturing model to evaluate production efficiency. Using the fractional production flowback results from the chemical tracer study, hydraulic fractures were calibrated to match the fractional production from each interval. The fracture model provides insight into what the hydraulic fractures look like, potential communication avenues for the chemical tracers, and production efficiency.