Development and Performance Evaluation of Nanocomposite Filtrate Reducer for Water-Based Drilling Fluid

In the process of developing deep and complex formations, the drilling fluid treatment agent is facing the problem of poor temperature and salt tolerance. In this paper, acrylamide (AM), dimethyldiallylammonium chloride (DMDAAC), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and KH570 modified nano silica were used as materials to synthesize a nano composite filter loss reducing agent (NSDA). The structure of NSDA was analyzed by infrared spectrum scanning, and its thermal stability was measured by thermogravimetric experiment. Added it to the water-based drilling fluid to evaluate its effect. Explored the mechanism of NSDA by analyzing the distribution of bentonite particle size, Zeta potential and filter cake microstructure analysis. The results showed that the product structure conformed to the molecular structure design. The decomposition temperature of NSDA reached 320℃, which had good thermal stability. After adding 1.0 wt% NSDA to base mud, the fluid loss of freshwater drilling mud after aging at 210℃ was 10.0 mL. After adding 2.0 wt% NSDA to the saturated brine mud, the fluid loss of drilling mud after aging under 180 ℃ was only 6.4 mL. Mechanism analysis suggested that NSDA molecular chain has strong rigidity and anti polyelectrolyte effect, which can still adsorb with clay particles at harsh environments of saturated salt and high temperature, thus inhibiting the agglomeration of clay particles and maintaining good colloid stability of drilling mud.