The Study Of Remaining-oil Distribution After Polymer Flooding And The Technical Policy Of Ponding And Profile Control In Shengtuo Oil Field

As more and more oil fields coming into the late period of high water cut and the period of extra-high water cut, the contradiction of developing oil fields becomes increasingly prominent, so polymer flooding as a major mining technology to improve oil recovery becomes increasingly important. As known to all, the oil recovery after polymer flooding is still low, so other methods must be used to further enhance the oil recovery after polymer flooding. Therefore, the distribution of remaining oil after polymer flooding has an important guiding significance for the selection of measures to further improve oil recovery.The remaining oil distribution rules are studied in the paper through combining measures of lab experiments, numerical simulation and theoretical analysis. In connection with the geological characteristics of Shengtuo oil field, visualized models and parallel long-tube core models for different types of reservoirs are made of quartz sand for the displacement experiments of polymer flooding, meanwhile, typical geological models are established using numerical simulation sofeware for the simulation of polymer injection development, and the remaining oil affecting factors and distribution rules are studied respectively for different types of reservoirs after polymer flooding. The results show that the distribution of remaining oil are basically the same between the physical model results and the numerical simulation results. In positive rhythm reservoir, the more serious the heterogeneity is, the higher the residual oil saturation is; the greater the viscosity of crude oil is, the lower the oil and water mobility ratio is, and the residual oil saturation is higher; the greater the polymer injection concentration is, the better the sweep extent of the low-permeability layer is, and the residual oil saturation is lower; the larger the planar polymer injection rate is, the lower the residual oil saturation is; the residual oil saturation in the model of combined concentration slug is slightly less than it in the model of single slug.In this paper, the corresponding technology policies of water shut-off and profile control are proposed for different situations of the remaining oil distribution on the basis of comparing the experimental results and numerical simulation results, which provide an important theoretical guidance to further improve the oil recovery as well as to guide the exploitation of sequent water flooding .The results show that the comprehensive benefit of water shut-off is better when the single-well plugged radius is 16.9m, and the plugged time is that the water ratio is 96 percent,and the plugged proportion is 100%. The plugged effect of positive rhythm reservoirs is better than the inverted reservoirs, and the greater the permeability is, the more obvious the plugged effect of reservoirs is. The greater the production rate is, the more obvious the plugged effect of reservoirs is. The plugged effect is the most obvious when the polymer injection concentration is 1600mg/L, and the polymer injection rate is 0.12PV/a. The larger the polymer slug volume and the series, the less obvious of the plugged effect.