Study On The Technology Of Enhancing Oil Recovery By Nano Displacement In Low Permeability Reservoir

The reserves of low-permeability reservoirs account for a large proportion of the total reserves of reservoirs in China.Due to the poor physical properties of reservoirs and the complex percolation mechanism,it is difficult to develop them.However,nano silica has a good prospect in improving the recovery of low-permeability reservoirs as an oil displacement agent due to its small volume and high surface energy.Therefore,it is of great significance to study the displacement behavior and mechanism of nano oil displacement agent under the condition of complex heterogeneous and low permeability reservoir.In this paper,the sand filled pipe is used to simulate the low-permeability heterogeneous reservoir,and the oil displacement ability of modified nano-SiO₂ is compared with that of surfactant and polymer.The oil displacement effect of six binary systems of modified nano-SiO₂ and polymer(anion,cation)/surfactant(anion,cation,amphoteric and non-ionic)is investigated,and the EOR machine of Nano-SiO₂ is explored Li.The experimental results show that the modified nano-SiO₂ and polymer are not suitable to be used alone as oil displacement agent in low-permeability reservoir;the dual system of nano-SiO₂ and lauryl betaine(1:2,1wt%)has the best oil displacement effect,with an enhanced oil recovery of 39.39%;the dual system of nano-SiO₂ and poly quaternary ammonium salt-7(1:2,1wt%)has an enhanced oil recovery of 30.43%;combined with six kinds of Nano-SiO₂ Based on the oil displacement effect of the binary composite system and the characteristics of nano silica itself,the key mechanism analysis chart of enhancing oil recovery of nano silica in low permeability reservoir is inferred,and the quantitative regression formula between the enhanced oil recovery,surface tension and static adsorption capacity of the binary composite system nano oil displacement agent is determined under the condition of low permeability reservoir The adsorption amount of nano silica on the rock surface is the key factor of EOR.