Comb polymer/layered double hydroxide (LDH) composite as an ultrahigh temperature filtration reducer for water-based drilling fluids

In deep-formation drilling, effective filter loss control in ultrahigh-temperature conditions and high-salt conditions faces challenges. Comb polymer/LDH composites (P-LDH) with partially intercalated and partially exfoliated structures were prepared by in-situ polymerization as fluid loss materials. A series of characterization results showed that the P-LDH composites were successfully synthesized. P-LDH had partially intercalated and partially exfoliated structures and excellent thermal stability. In addition, the rheological evaluation results showed that P-LDH had a low viscosity effect while maintaining the rheological properties of the drilling fluid. PLDH can significantly reduce the filtrate loss of drilling fluids at ultrahigh temperatures and high salt concentrations. At 240 degrees C and 15 wt% NaCl, the filtration loss was only 6.3 mL, and the high-temperature and highpressure filtration loss was only 29.6 mL. Through the analysis of drilling fluid particle size and filter cake microstructure, based on hydrogen, ionic bonds, and intercalation effects, P-LDH acted closely with bentonite to promote stable dispersion, improve the drilling fluid's stability, and form a dense filter cake to reduce the filtration loss. Therefore, P-LDH has broad application prospects in ultrahigh-temperature and high-salinity formation drilling.

Automated summary

This study successfully synthesized P-LDH composites with partially intercalated and partially exfoliated structures by in-situ polymerization. The P-LDH showed excellent thermal stability and low viscosity effect, which significantly reduced the filtrate loss of drilling fluids under ultrahigh-temperature and high-salt conditions.