| The PudBei 125 well area is located in the middle of the fault block in the north of Portugal.The main oil-bearing formation is the Portuguese I group oil reservoir,and the reservoir depth is relatively shallow 800 to 1000m.The reservoir has an average porosity of 14.34%,an average permeability of 298.0×10-3?m2,an average temperature of 47.4?,and an oil field formation salinity of 8490-9978 mg/L.The reservoir has strong heterogeneity,low level of waterflooding control,large proportion of one-way communication,large differences in production between wells,ineffective circulation of water injection within layers,large contradictions between layers,poor utilization of thin and poor oil layers,and a gradual decline in polymer flooding effects.The water content keeps rising and the production wells are not effective.It is urgent to change the development mode and control the increase of water content.In this paper,according to the characteristics of the strong heterogeneity reservoirs in the Pu 125 test area and the problems existing in the development,it is proposed to use polymer/hole throat microspheres to increase the efficiency of flooding and polymer flooding.Based on the controlled flow of polymer flooding,through the addition of polymer/hole throat microspheres,the ability of the microspheres to gradually adjust the flooding,enhance the ability of the polymer to turn,and delay the unidirectional breakthrough of the polymer,thus continuously Start the thin differential oil layer to realize full-range flooding.According to the pore throat diameter of the reservoir in the Pu-125 test area,the WQ-I with the average particle size of 4.420?m microspheres was selected according to the“1/3 to 2/3”bridging principle of the particulate blocking agent;WQ-I in the water Good dispersion,good temperature and salt tolerance,the expansion ratio of the microspheres under reservoir conditions is 1.25 particle size of 9.842?m;after 60 days in the reservoir conditions,the microspheres have good roundness,and the particle size range is still There are 11.15 ?m to 12.55 ?m.During the injection process of the microspheres,the injection performance is good,and the injection pressure is continuously up and down.The maximum resistance coefficient of the injected microspheres is 23.92,and the maximum residual resistance coefficient is 9.17.Under reservoir conditions,the polymer/microsphere system has good compatibility with fresh water and formation water;the polymer/microsphere system has a better viscosity-increasing effect than the addition of the same quality polymer;after the composite system is cut The viscosity retention rate is above 65%?and the shear resistance is strong.The microstructure and viscoelasticity of the system after addition are better than that of a single system,and the temperature and salt resistance and stability are good.The resistance coefficient and residual resistance coefficient are respectively 34.41 and 16.64 showed better fluidity control and plugging capabilities.The injection parameters of the polymer/microsphere were optimized by flooding experiments.When the amount of microspheres in the 1000 mg/L polymer solution was 0.2wt%,0.3PV was injected into the slug and the recovery factor was 15.46%..Different injection methods have shown that the use of mixed injection can significantly increase recovery.The parallel core flow experiment shows that the polymer/microsphere system has obvious effect on the start of low permeability pipe,which makes the high and low permeability pipe flow rate tend to 50%.Subsequent flooding caused the flooding system to move deeper into the sand filling pipe and could achieve full-range flooding.The study of the improvement of water absorption profile shows that the compound displacing agent can effectively drive the low permeability layer,and the larger the permeation differential is,the more obvious the profile improvement rate is,the profile improvement rate reaches 77.41%?83.15%,and the enhanced oil recovery can reach 15.61%?15.98%.In this paper,the results of the research on the addition of polymers and microspheres have been made.It is of great significance to improve the development of the Pu 125 test area. |
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