Drilling fluid plays a critical role in drilling engineering. With the deepening implementation of clean production concepts and increasingly stringent environmental regulations, the treatment standards for drilling wastewater at operational sites have been significantly elevated. In response to the characteristics of high oil content, high COD, high chromaticity, high ammonia nitrogen, and total phosphorus content in drilling, the use of fine bubbles to improve gas utilization efficiency and mass transfer effect, combined with ozone gas, is aimed at degrading difficult-to-degrade high-molecular-weight organic compounds, aiming to solve the problems of high viscosity and high oil content in drilling fluids returned from offshore platforms. Indoor simulation experiments have shown that by using ozone fine bubble technology to treat drilling fluids, the viscosity reduction rate can reach over 29%, and the oil removal rate can reach 40%. Ozone fine bubble technology has significant viscosity reduction and oil removal effects on high viscosity drilling fluids.

The treatment of high-viscosity oil-bearing drilling mud from offshore platforms is constrained by limited space and stringent environmental regulations, yet no previous study has demonstrated the combined application of ozone-assisted micro-nano bubble (MNB) oxidation with filtrate recycling for this specific waste stream. Here, we address this gap by integrating ozone MNB treatment, flotation oil removal, and filtrate reuse into a unified process for the viscosity reduction and deoiling of water-based drilling mud. Experimental results show that the ozone MNB process achieves a viscosity reduction rate exceeding 50.2% and an oil removal rate of 60.87%, with filtrate ion concentrations (Ca²⁺ 382 mg/L, Mg²⁺ 1380 mg/L, SO₄²⁻ 1107 mg/L) within reuse thresholds. Drilling fluid reformulated with the recycled filtrate maintains consistent rheological properties before and after thermal aging. These findings demonstrate that the coupled ozone MNB treatment-reuse strategy is scientifically viable for managing high-viscosity drilling waste, advancing beyond conventional disposal approaches by enabling simultaneous viscosity reduction, oil removal, and resource recovery within a compact process footprint.