Development and Application of Smart Polymeric Nanoparticles for Matrix Acidizing: Evaluation with a Novel Permeameter.

Matrix acid stimulation is widely used in carbonate reservoirs to enhance oil production by injecting an acid fluid under conditions determined by pressure, acid concentration (3 to 35%), flow rate, and temperature (50 to 180 °C) [1]. The fluid dissolves formation damage, increasing permeability and creating channels known as wormholes [1]. Hydrochloric acid ("HCl" ) is the most used solution; however, it presents limited reaction control, high operational costs, and corrosive behavior toward equipment [2]. Therefore, this research investigates smart nanoparticles as alternatives to conventional "HCl" fluids. Nanoparticles were synthesized by emulsion polymerization with two morphologies—core-shell and core-concentration gradient—and functionalized with carboxylic (AA) and amide (AAm) groups at three compositions: 70:30, 80:20, and 90:10 wt.%. The nanoparticles were characterized by DLS, Zeta potential (ζ), rheology (viscosity η, storage G', and loss G'' moduli), and SEM from 25 °C to 60 °C. Additionally, a custom permeameter was designed and calibrated to evaluate the dispersions using carbonate core samples from Mexican oil reservoirs. Results showed average particle diameters from 250 to 1200 nm and high colloidal stability (ζ=-46" to "-22" mV" ). Rheological analysis exhibited non-Newtonian behavior, where viscosity decreased as temperature (40, 50, and 60 °C) and shear rate (0.01" to " 100〖" s" 〗^(-1)) increased. FT-IR spectra confirmed functional groups on the surface, while SEM revealed distinct surface morphologies, indicating structural changes in response to temperature. The permeameter consists of an acid storage and pressurization system, a thermally controlled reaction cell, and a product recovery module. Initial test cores composed of cement and sand (porosity 0.2–0.3) showed high calcite content via FT-IR and XRD, promoting reaction with the latex material to increase permeability. Finally, the physicochemical properties, porosity, and permeability changes will be evaluated at 25, 40, and 60 °C under atmospheric pressure to assess their potential for controlled matrix acidizing.