Preparation and Performance Evaluation of Oil-Absorbing Expansive Particles for Oil-Based Drilling Fluid

Abstract

With the development of deep and ultradeep wells advances, oil-based drilling fluids play a significant role. To enhance the plugging performance of oil-based drilling fluids, this study synthesizes an oil-absorbing expandable particle, P(AM-SMA-St-DVB), which was prepared by solution polymerization and used acrylamide (AM), stearyl methacrylate (SMA), styrene (St) as reaction monomers; divinylbenzene (DVB) as a cross-linking agent; polyvinylpyrrolidone (PVP) as a dispersant and 2,2′-azobis (AIBN) as an initiator. Through methods including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis-differential scanning calorimetry (TGA-DSC), contact angle analysis, particle size analysis, oil absorption testing, and oil-based drilling fluid performance testing, the structure and properties of this particle were investigated. The results indicate the successful synthesis of the target product with a well-defined three-dimensional network structure. The particle demonstrates excellent thermal stability, remaining nearly intact until around 450°C. The contact angle between the particles and water exceeds 90°, indicating its hydrophobic and oleophilic nature. Oil absorption levels stabilize within 10 min with an absorption ratio exceeding four across various temperatures, showing significant stability and excellent absorption capacity. When added to the drilling fluid system, P(AM-SMA-St-DVB) particles reduce fluid loss at ambient and high temperatures as well as after aging, while maintaining stable rheological properties for oil-based drilling fluids.