To improve the selective fluid conductivity of proppants in hydraulic fracturing, a hydrophobic quartz sand proppant was developed using a cost-effective, water-dispersible formulation composed of dodecylamine (DDA), diesel, and sec-octanol. The modified sand exhibited strong hydrophobicity (contact angle 110.4° vs. 63.4° for raw sand) and retained stability after 72 h water flushing, six months air exposure, and heating at 150 °C for 8 h. The proppant maintained its hydrophobicity in high-salinity brines (up to 10,000 mg/L) and in solutions containing 12% cetyltrimethylammonium chloride (CTAC), 0.25% polyacrylamide (PAM), and across a pH range of 5–9. X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) confirmed the surface adsorption of amine functional groups. The incorporation of diesel and sec-octanol enhanced the dispersion and uniform adsorption of DDA, improving interfacial modification while minimizing foaming. Water-blocking tests showed the modified sand supported a 42 mm capillary column and effectively delayed water breakthrough. Conductivity tests demonstrated enhanced oil flow capacity under closure pressures up to 30 MPa. These results indicate that the hydrophobically modified proppant can effectively suppress early-stage water invasion and improve oil productivity, offering strong potential for applications in tight and low-permeability reservoirs.
Wang et al. (Wed,) studied this question.