Experimental Study on Dual Flooding of Low Permeability Heterogeneous Reservoir

Jurassic low permeability reservoirs with permeability less than 50mD in Changqing oilfield have strong heterogeneity, Now it's the "double high" stage, so it is urgent to explore enhanced oil recovery technology. In this paper, polymer and binary flooding experiments were carried out in parallel with cores of 30mD, 120mD, 160mD and 300mD to study the adaptability of binary flooding for low permeability heterogeneous reservoirs. The experiments show that the selection of appropriate polymer molecular weight and proper viscosity for binary flooding in low permeability heterogeneous reservoirs can not only ensure injection, but also increase the injection pressure. Improve the diversion rate of higher and lower permeability reservoir, expand the sweep volume of lower reservoir, and improve the oil displacement efficiency of heterogeneous reservoir. If the permeability is less than 10mD, the dual system cannot be injected into the reservoir.The permeability level difference of the reservoir is more than 6. Before the dual flooding, it is necessary to carry out profile control and block large pore to ensure the dual flooding effect. After the polymer is produced in the higher permeability layer, the diversion rate of each small layer in parallel core basically returns to the water flooding value, and the subsequent water flooding effect is not obvious. Therefore, profile control should be carried out after the accumulation of dual flooding.