Compatibility and Salt Sensitivity Analysis of Rhodamine-B as a Fluorescent Tracer in Water-Based Drilling Fluids for Wellbore Monitoring Applications

Abstract

Drilling fluids are essential for maintaining wellbore stability, controlling subsurface pressure, and transporting cuttings to the surface. However, real-time monitoring of fluid pathways and loss zones remains a challenge. One promising solution is the integration of fluorescent tracers into water-based mud (WBM), allowing visualization under UV light. Rhodamine-B (RhB) is widely used due to its strong fluorescence and high water solubility, yet its performance depends on compatibility with mud additives and its stability under saline and thermal conditions. This research analyzes the impact of RhB addition on mud properties and fluorescence response in WBM, both with and without KCl. Formulations using RhB concentrations of 0.03 g, 0.06 g, and 0.1g were tested for rheology, fluid loss, fluorescence, and aging tests at room temperature and 80°C for 8, 16, and 24 hours. Results showed that RhB is generally compatible with most additives, but strongly adsorbed by bentonite, reducing fluorescence. Fluorescence also declined in salt-rich conditions due to dimerization and quenching. Mud with 0.06 g RhB showed the most notable rheological changes, while 0.03 g RhB maintained optimal stability due to its resemblance to the base mud. Thermal aging reduced fluorescence over time.