(116e) Novel Star Polymer for Efficient Fluid Loss Control in Oil-Based Mud

Oil-based mud (OBM) is an important drilling fluid in high temperature environments due to its reliability and effectiveness. Fluid loss control additives are necessary to prevent excessive filtration loss into the formation and to achieve minimal filter cake thickness.

This study focused on developing a new star polymer for fluid loss control in OBM, which was synthesized using Reversible Addition Fragmentation Chain Transfer polymerization (RAFT). The star polymer showed remarkable fluid loss control properties compared to traditional natural and synthetic based additives. Various fluid properties such as rheology, fluid loss, mud cake thickness, and emulsion stability were evaluated for OBM at simulated downhole pressure and temperatures and compared with commercially available additives.

Spectroscopic analysis and thermogravimetric analysis confirmed the desired chemical architecture and thermal stability of the star polymer, which remained stable up to 350 °F. The addition of the star polymer had a negligible effect on plastic viscosity (PV), which is usually increased with the addition of other fluid loss control additives. The study was conducted on both diesel and mineral oil-based mud systems, and high temperature and high-pressure viscometers were used to investigate rheological properties at up to 10,000 psi and 350 °F.

The results of the study showed that the star-polymer was a highly effective fluid loss control additive with excellent thermal stability, low PV, high emulsion stability, and an ultrathin filter cake for OBM systems. This new molecule has the potential to improve the performance of high-temperature drilling operations and can be easily synthesized and scaled-up commercially.