Fluorescent tracers for drill cuttings labelling - compatibility with oil-based drilling mud, long-term stability, and possibility of the recovery.

Tracers are specialized compounds that are often used in the modern oil and gas industry. Tracing is one of the methods of comprehensive reservoir characterization used along with production rate monitoring of reservoir fluids, 4D seismic, and others for modeling of downhole processes. Tracers are typically used in oil production and reservoir monitoring in the single-well tracer tests and interwell tracer tests with or without partition. The current work proposes innovative use of engineered fluorescent tracers for color tagging of drill cutting at the drill-bit site to determine the depth of cuttings formation.

Previously we reported synthesis and laboratory characterization of novel composite fluorescent tags [1]; at the current work we perform extensive evaluation of operational properties of the obtained materials.

Namely, we examined the effect of tracer’s additives on the rheological characteristics of the oil-based drilling mud, electrical stability, and thixotropic parameters of the drilling emulsion as well as on shear stress, gel strength, plastic viscosity, and yield point. The hot rolling test mimics conditions of mud and formation cuttings circulation in the well and demonstrated the possibility of tracers’ recovery and reuse. It was noted that tracers retain fluorescence and could be detected visually even after 4 months of exposure to the drilling fluid.

Thus, we demonstrated the compatibility of fluorescent tags with oil-based drilling mud and their suitability for downhole applications. Our ongoing work is focused on the development of tracers’ detection system via camera at the shale shaker.

[1] Khmelnitskiy, V.; AlJabri, N.; Solovyeva, V. Preparation and Selection of Best-Performing Fluorescent-Based Tracers for Oil and Gas Downhole Applications. Processes 2022, 10, 1741. https://doi.org/10.3390/pr10091741