Wang-17 Block of Wangji Oilfield is the first zone in China to carry out polymer flooding EOR test with multi-stage heterogeneous profile control slug in oil reservoirs with low-medium permeability. The objective is to form the matching technology of chemical flooding in small fault block and low-medium permeability reservoirs

and to lead

demonstrate and use the remaining Class I and Class II chemical flooding reserves of 3 512×10

4

t in Henan Oilfield. The keys of the technology are adaptability of flooding agent to reservoir

effective plugging of extreme water-consuming layers and well pattern adjustment. Therefore

starting with the adaptability of polymer and preformed particle gel（PPG） to reservoir

the grain size distribution of PPG and the

factors affecting water absorption and swelling of viscoelastic particulate have been studied and the salt resistance

shear resistance and thermal stability have been characterized. Meanwhile

the relation between particle number and concentration

the possibility of injection

the oil displacement efficiency and the diversion rate of heterogeneous system have been evaluated. The results show that the optimized heterogeneous flooding system has better adaptability to low-medium permeability reservoirs. Field application has achieved the effect of increasing oil production and reducing water

which provides technical support and significant reference to EOR in the similar oil reservoirs.