The Effect Of Water Re-injection On The Water Absorption Capacity Of Water Injection Wells

Produced water reinjection is one kind of waterflooding which could effectively enhance oil recovery in field and is able to solve the problem of environmental pollution and waste of resources. However, a great quantity of suspended particles, emulsified oil droplets, bacteria and chemical agents in produced water and the scale caused by the incompatibility between produced water and formation water will probably cause formation damage and decline of injectivity. Hence, it is meaningful to the steady production operation to establish and amend mathematical model for scaling type, scaling mechanism, and the mechanism of migration and capture of particles. This paper studied the following aspects:Firstly, based on a great deal of the records and literatures, the mathematical model for particle filtration was elaborated, and the impedence of the core on the deep bed filtration stage and the filter cake formation stage was fitted.Secondly, the ion distribution model for linear and radial flow was thoroughly studied, a different numerical method was employed for parameter fitting and the flow process was simulated through software.Then, the effect of suspended particles and barium sulfate under different influence factors on injectivity index was studied through core flooding experiment.Specific results are as follows:(1) The core impedance of different stages was obtained by subsectional fitting and the effect of particles of different phases on the impedance was compared in the model for particle filtration;(2) The more accurate result of the model parameters was obtained through the numerical solution of the transcendental equation and the curves of impedence and ion distribution under different ion concentration ratios were compared in the ion distribution model for linear flow;(3) The scale was simplified by the introduction of point source and the process of the flow was simulated through COMSOL Multiphysics in the ion distribution model for radial flow;(4) The effect of particles under different temperatures, fluxes, concentrations and diameters on the injectivity index was studied by core flooding;(5) The effect of barium sulfate under different temperatures, pH, fluxes and concentrations on the injectivity index was studied by core flooding.