| Zhao 86 fault block reservoir is a high temperature and high salinity block reservoir of Huabei Oilfield, water channeling and flooding is serious between oil wells in the reservoir, the validity of conventional profile control and displacement is short and the results is poor, in this case, this block urgently needed an effective technique of deep profile control and displacement, to improve the deep flow of reservoir, increase the role of oil and water control, increase ultimate recovery reservoir. Nanospheres deep profile control and displacement technology is a new proposed technique. Nanospheres which become gel on the ground, can reduce the effects of salinity, formation temperature, formation shear and other environmental factors of system. Nanospheres have a small initial size, low viscosity, injection process is simple, expansion time can be controlled, progressively plugging can be achieved in low permeability oilfield.In this paper, we developed a nanosphere, using of inverse emulsion polymerization method, which adapt to Zhao 86 fault block formation and reservoir fluids characteristics of the formation, and evaluated its basic performance with the interior core flow experiments, evaluated the adaptability between nanosphere and Zhao 86 fault reservoir block, preferably a suitable optimum injection parameters of the reservoir, and finally use the best optimized injection parameters evaluate their effect deep profile control and displacement.The results shows that:Nanospheres synthesized has an initial average particle diameter of 405.87nm, and has good swelling properties, nanospheres’expansion multiples is 35.52, after absorbing 24h at 80 ℃,1% NaCl brine, and the higher the temperature, the lower the salinity, the smaller the pH value, the greater the expansion multiples of nanospheres, and the better expansion performance; Microspheres has obvious viscoelastic properties after absorbing water, and exhibit properties of a soft solid, and has good resistance to shear capacity at high shear rates; nanospheres has good compatibility for Zhao 86 fault block reservoir, by measuring the resistance factor and residual resistance factor we found that:the nanospheres system has good mobility in low permeability cores, can migrate into the deep core, the blocking rate of nanospheres dispersed system for rocks is greater than 95%, it has a significant anti-erosion performance in permeability range of 30 ～ 100 × 10-3 μm2; By nanospheres parameter optimization experiments, preferably a nanosphere system optimum injection parameters:Injection at a concentration of 2000mg / L, injecting an amount of 0.2PV, injection rate of 0.3mL / min, injection method 0.1PV microsphere + 0.1PV water + 0.1 PV microspheres; Flooding effects of Nanospheres system for square heterogeneity core and three parallel natural cores are good, the oil recovery rate of the square heterogeneous cores up to 17.29 percent based on water flood. By injecting a small amount of pre-polymer profile before injecting nanospheres system when, reservoir heterogeneity is serious, the flooding effect is more obvious, compared with water flooding the ultimate recovery increasel8.59%, higher 0.74% than the profile that not carry out the pre-polymer recovery profile, which is 17.85%; Microscopic oil displacement experiments showed that Nanospheres system have a good effect, both for the waterflood not spread to the continuous oil zone, or trapped in the pores on several types of residual oil (columnar, film, film, clusters), Nanospheres system reflects better sweep efficiency and wash oil efficiency. Flooding mechanism of nanospheres system are:a cross-sectional selective transfer mechanism; deep flow steering mechanism; nanospheres deformation flooding mechanism.The research results can provide laboratory experiments and theoretical support for the application of nanoparticles in Zhao 86 fault block reservoir, It is important for further EOR and achieve sustainable development of Zhao 86 fault block reservoir. |
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