Thermal-setting resin-modified silica nanocomposites for self-regenerating and wide plugging distribution in water-based drilling fluids

Abstract

Effective pore and fracture plugging typically requires the integration of various types and sizes of particles, ranging from nanoscale to microscale, to minimize drilling fluid invasion into the formation. Here, we report novel thermosetting silica nanoparticles decorated with resin (RSNP), which not only retain their nanoscale distribution even at high temperatures but also promote the formation of micrometer-sized particles through interactions with clay in drilling fluids. Characterizations using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis and Differential Scanning Calorimetry (TGA-DSC), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM) were employed to confirm the chemical structure of the synthesized silica nanoparticles and their interaction with clay in the drilling fluid. The plugging effectiveness was systematically assessed using various filter media and natural shale rock samples. TEM and SEM images revealed a narrow, monodisperse particle size distribution of the synthesized silica nanoparticles in the nanoscale, which were found to adsorb on the edges and surfaces of clay lamellae. Original pores and fractures were effectively sealed by silica nanocomposites of comparable size. The strong adsorption of silica nanocomposites on clay particles facilitates clay flocculation in the water phase and expels water molecules from the clay interlayer due to the intercalation and plugging effects of the silica nanocomposites, thereby inhibiting water invasion. Due to the thermosetting nature of the silica nanocomposites, which encapsulate and bridge clay particles at high temperatures, the drilling fluid evolves from a monodisperse to a bimodal particle size distribution, particularly under high-temperature conditions. This transition results in the formation of micrometer-sized particles in water-based drilling fluids, effectively matching the pore and fracture sizes ranging from nanoscale to microscale. These findings offer a novel strategy for designing nanocomposites for multi-stage plugging, optimizing additive usage while minimizing drilling fluid invasion into porous formations.