Polymers marry with carbon nanospheres: A promising strategy to develop high-performance filtrate reducer

Polymeric filtrate reducers have limited uses under high temperature and salinity conditions. The incorporation of nanoparticles to polymeric networks is a popular and effective method for creating high-performance filtrate reducers. However, present nanofillers are costly, have negative environmental consequences, and are difficult or impossible to disseminate. Herein, a simple hydrothermal process using low-cost and renewable glucose as raw ingredients resulted in hydroxy-rich carbon nanospheres (CNs). After modification by acryloyl chloride, the CNs were copolymerized with acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and sodium p-styrene sulfonate. The obtained CNs-doped polymers (CAAS) were able to maintain high viscosity and colloidal stability even after salt contamination and high temperature aging. CAAS-based drilling fluids can tolerate temperatures of up to 240 °C under 30 % NaCl conditions. The API filtration loss (FL_API) and the high-temperature high-pressure filtration loss (FL_HTHP) were 10 and 63.5 mL, respectively. Considering the low-cost and renewable raw materials, high dispersibility and high compatibility of CNs as well as significant improvement in thermal-resistance and salt-tolerance, this work provides a simple yet effective approach to developing high-performance filtrate reducers for complex geological conditions.