Fuzzy-ball fluid for stabilizing oil production and water control in formations with high-salinity water

To clarify the performance of fuzzy-ball fluid in stabilizing oil production and water control in formations with high-salinity water, the constant flow velocity was used under temperature of 120 ℃, confining pressure of 15 MPa and backpressure of 1.5 MPa to determine changes in permeability and injection pressures of steady flow in man-made sandstone columns with kerosene and salt water of various salinities before and after plugging by fuzzy-ball fluids. Test results show that, under constant flow rate of 0.1 mL/ min, displacement pressures of formation water containing Fe2+, Ca2+ and Mg2+ with salinity of 1×104 mg/L, 10×104 mg/L, 20×104 mg/L, respectively, increased from 0.46-0.63 MPa to 1.39-2.23 MPa, plugging capabilities increased by 205.83%-262.64%, and permeability decreased from 140.82-193.30 mD to 66.96-109.85 mD with a losing rate of 43.15%-52.53% after plugging by the fuzzy-ball fluid. In addition, kerosene was used to simulate formation oil to determine plugging performances under identical conditions. The results show that displacement pressures increased by 5.83%-8.08%, from 0.48-0.52 MPa to 0.51-0.55 MPa, and permeability decreased from 232.05- 272.52 mD to 211.09-249.25 mD with losing rate of 2.26%-4.51%. Fuzzy-ball fluids were applied in Well Y and Well Z with formation water salinity of 8×104 mg/L and 4×104 mg/L for stabilizing oil production and water control. By promoting pumping frequency and deeper pumping, water production in these wells decreased by 46.38% and 15.99%, whereas oil production increased by 6 200% and 180% respectively. These research results and application performances suggest that the fuzzy-ball fluids with resistance to high-salinity formation water can be deployed for stabilizing oil production and water control.