Polymer-laponite composites as filtrate reducer for high temperature and salt resistant drilling fluid: Characterization and performance evaluation

In deep and ultra-deep well drilling, ultra-high temperatures and high salt lead to poor drilling fluid performance. In this study, N, N-dimethylacrylamide (DMAA), dimethyldiallylammonium chloride (DMDAAC), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), 4-acryloylmorpholine (ACMO) and modified laponite (m-LAP) were polymerized into polymer nanocomposites PDADA-LAP by free radical polymerization in aqueous solution. The structure of PDADA-LAP was characterized by FT-IR, 1H NMR and XPS. The microstructure of PDADA-LAP was characterized by TEM, SEM and EDS. The results showed that LAP improved the network structure of the polymer by hydrogen bonding and covalent bonding. The effect of temperature on the degradation of the polymer solution was investigated. The experiment showed that the degradation temperatures of the polymer was 220 °C. PDADA-LAP was used as a filtrate reducer in drilling fluids. The results showed that 3.0 wt% PDADA-LAP could improve the filtration performance of drilling fluids at high temperature of 220 °C and resist contamination with 20 wt% NaCl. The FLAPI and FLHTHP were 7.0 mL and 28.6 mL, respectively. PDADA-LAP is adsorbed on bentonite particles through hydrogen bonding and electrostatic interaction, which slows down the contamination of bentonite particles by NaCl and gives the drilling fluid a good effect to reduce fluid loss at high temperature and high salt. [Display omitted] •A polymer- laponite composite PDADA-LAP used as filtrate reducer.•The PDADA-LAP effectively controls the filtration loss of drilling fluid at 220 ℃ and 20% NaCl.•The thermal degradation experiment of polymer PDADA-LAP solution showed that the temperature resistance of polymer was 220 ℃.•Laponite improves the spatial network structure of polymers through hydrogen and covalent bonds.