Study on the Water Blocking Capacity and Influencing Factors of Hydrophobic Gravel Beds

Excess water production is a common and extremely serious problem during the process of reservoir development, especially in the middle and later stages of unconsolidated sandstone reservoirs. High water content ratios will negatively affect the recovery efficiency and equipment safety of oil and gas wells. In this study, a hydrophobic quartz sand proppant was prepared with 1,1,1,3,3, 3-hexamethyldisilazane (HMDS) for gravel packing technology. The capillary resistance of hydrophobic quartz sand beds to water was used to achieve water inhibition and oil enhancement. Then, a theoretical capillary bundle model of a quartz sand bed was developed to predict the capillary resistance and water blocking capacity of the quartz sand bed. An evaluation of the experiment results shows that the activation index is up to 96% and the water contact angle is up to 151° after treatment by 0.6 wt % HMDS, which indicates that the quartz sand after modification has strong hydrophobicity. The calculation results demonstrate that the capillary resistance (CR) and the water blocking capacity (WBC) decrease with increasing quartz sand particle size and porosity of the quartz sand bed. As the water contact angle increases, the CR and WBC are also increased. In addition, to make the WBC of hydrophobic quartz sand bed δ > 20%, the parameters of the quartz sand bed must be satisfied: particle size d _g < 50 μm, porosity ϕ < 30%, water contact angle θ > 150°, and production pressure difference Δp < 1 MPa. The results of this study could provide theoretical guidance for the construction parameters of hydrophobic gravel packing in high water-cut oil and gas fields.