Nanolaponite/Comb Polymer Composite as a Rheological Modifier for Water-Based Drilling Fluids

Abstract

During the drilling of deep/ultradeep wells, water-based drilling fluids (WBDFs) often experience harsh conditions of ultrahigh temperature and high salt. Ultrahigh temperatures and high salts cause rheological instability in drilling fluid, reducing its suspension and cutting-carrying capacity. In this study, a comb polymer, P-TPEG with isopentenol polyoxyethylene ether (TPEG) as the side chain, was prepared via free radical polymerization in an aqueous solution and then compounded with nanolaponite (LAP) to obtain a composite rheological modifier (LAP/P-TPEG). In situ Fourier transform infrared spectroscopy and thermogravimetric analysis showed that LAP/P-TPEG had an excellent thermal stability. The LAP/P-TPEG solution test showed a shear thinning behavior. The results demonstrate that LAP/P-TPEG can improve the rheology of WBDFs before and after aging at 240 °C and can resist 15 wt % NaCl. LAP/P-TPEG formed a strong adsorption with bentonite through hydrogen bonds and electrostatic interactions. LAP, P-TPEG, and bentonite formed a “reversible” “dual” spatial network structure in WBDFs, improving the rheology and the suspension, cutting-carrying, and wellbore-cleaning abilities of the drilling fluid under ultrahigh temperature and high salt.

Laponite®—From Dispersion to Gel—Structure, Properties, and Applications

“…The new LAP/isopentenol polyoxyethylene ether composite enhances the rheological properties of water-based drilling fluids under various conditions, including before and after aging at 240 °C, and it demonstrates resistance to 15% NaCl [ 173 ]. In water-based drilling fluids, the combination of LAP, isopentenol polyoxyethylene ether, and bentonite creates a flexible and robust network, allowing for better suspension and efficient transport of debris.…”

Polymer–SiO2/Laponite Composite as a Filtrate Reducer for High-Temperature and High-Salt Drilling Fluids

“…This stabilizes the spatial network structure among drilling fluid constituents, 48 resulting in improved filtration and rheological performance of drilling fluids under high-temperature, high-salt conditions. 45,49 In our previous studies, we have demonstrated that polymers undergo thermal degradation in high-temperature environments. 50 Utilizing the destruction of the polymer network structure at high temperatures releases polymer nanoparticles to plug the pores of the filter cake, thereby maintaining the filtration performance of drilling fluids under high-temperature conditions.…”

“…LAP serves as a dispersant, suspending agent, and viscosifier, demonstrating excellent high-temperature performance when combined with bentonite-based slurries. − Furthermore, LAP can adsorb onto polymer chains via electrostatic interactions and hydrogen bonding , or be incorporated into the spatial network structure of polymers through graft copolymerization, , enhancing polymer thermal stability. This stabilizes the spatial network structure among drilling fluid constituents, resulting in improved filtration and rheological performance of drilling fluids under high-temperature, high-salt conditions. , …”