Acrylamide-Based Polymer/Laponite Composite as a Filtration Reducer in Water-Based Drilling Fluids

Abstract

With deep and ultra-deep drilling engineering, silane coupling agent KH-570 was used to modify the surface of nanolaponite, and acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), N-vinylpyrrolidone (NVP), and dimethyldiallylammonium chloride (DMDAAC) were selected as monomers. A new fluid loss agent, YH-1, was synthesized by aqueous solution polymerization, and the copolymer was characterized by infrared spectroscopy, nuclear magnetic resonance hydrogen spectroscopy, TEM, molecular weight analysis, and thermal stability analysis. The results show that the synthesized product is consistent with the molecular structure design goal. The modified nanolaponite was successfully introduced and relatively uniformly distributed in the filtrate reducer, and the molecular weight distribution was wide. After hot rolling at 240 °C for 16 h, it can still maintain good apparent viscosity, plastic viscosity, and dynamic plastic ratio. When the addition amount is 1.5 wt %, the apparent viscosity can still be maintained at 40 mPa•s, and its high-temperature and high-pressure (HTHP) filtration loss is the lowest compared with the domestic and foreign commercial filter loss reducers. Through particle size distribution, scanning electron microscopy, and zeta potential analysis, the surface of the filter cake formed after adding YH-1 was smooth and shiny, and the hydration film of bentonite particles was thicker. The adsorption group is adsorbed on the surface of bentonite particles, and the hydration group ionizes a large number of negatively charged groups, which increases the thickness of the hydration film of the bentonite particles and the potential of the bentonite particles. The addition of nanolaponite enhances the plugging effect of mud cake, improves the impermeability of mud cake, and enhances the filtration performance.