The Technology of Classified Combination of Deep Profile Control in the Bohai Oilfield

Based on calculation of the pressure index for profile control decision-making, laboratory experiments for selecting profile control agents, and design of profile control parameters, the particle grading combination for deep profile control technology was studied. Laboratory experiments showed that injection of high-intensity(final frozen strength 0.07 MPa)profile control agent in continuous phase after injection of low-intensity(final frozen strength 0.05 MPa)agents provided a recovery efficiency 3.1% higher than that by reverse injection sequence, and injection of profile control agent with small particle size(initial particle size 0.5-3.0 μm)in dispersed phase after that with large particle size(initial particle size 50-500 nm)contributed a recovery efficiency 4.1% higher than that by reverse injection sequence. Highest plugging rate was obtained when the ratio of dispersed phase particle size after expansion to the size of pore throat inside formation was 1, and it was required that initial particle size was less than 1/7 of pore throat diameter, and minimum size of particles after expansion greater than 1/3 of pore throat diameter. The application of the technique in the Bohai Oilfield was analyzed, water cut declined by 5.0% and oil increased 3.4×104 m3 in two clusters of wells through particle size grading and combination for controlling deep profile. The research results showed that, if the target well is determined using the parameters for overall profile control, appropriate profile control agent is selected according to the reservoir property, optimized combination of profile control system is conducted, the best effect of profile control can be achieved.