Numerical Simulation Of Effect Of Low Frequency Pulse Wave On Porosity And Permeability Parameters Of Low Permeability Reservoir

The low frequency pulse wave oil recovery technology uses the energy produced by the fluctuation to make the oil layer and its fluid produce physical and chemical changes,so as to improve the percolation condition of the oil layer,remove the blockage of the oil layer,create an environment conducive to the flow of crude oil,and achieve the purpose of increasing the production of oil wells and increasing the injection of water injection wells.This technology has the advantages of good oil enhancement effect,low construction cost,no damage to the reservoir,and no pollution to the environment.However,in the field test,the problem of‘unstable reservoir effectiveness'limits the application and development of this technology.The research on the dynamic mechanism of low-frequency pulse wave oil recovery technology is the key to improve its application effect.Based on Biot poroelastic theory in seismic exploration,combined with the existing experimental research results of low-frequency pulse wave oil recovery technology,a dynamic model of elastic wave propagation in porous media under the condition of single-phase seepage is established.Through the mathematical model equation derivation and numerical discretization,the PML perfect matching layer is introduced to establish a one-dimensional simulation physical model,and the numerical solution of the fluid-solid coupling model is obtained.The reliability of the model is analyzed by comparing the numerical simulation and experimental variation of permeability increment and frequency.The influence of low frequency pulse wave oil recovery on reservoir porosity and permeability parameters,fluid seepage velocity,and sensitivity to vibration frequency and amplitude are evaluated.The results show that for homogeneous reservoir,low frequency fluctuation has fluctuation effect on reservoir physical properties and fluid seepage velocity.For reservoirs with different porosity and permeability conditions,the low frequency fluctuation makes the porosity and permeability of the layers with poor porosity and permeability conditions improve more,and the seepage velocity of the fluid is faster.Under the action of low frequency wave,the maximum increase of porosity and permeability of low permeability reservoir is 4.6%and11.7%respectively.The seepage velocity of fluid can reach 1.6×10^-3m/s.The change of porosity and permeability is different when the vibration frequency and amplitude of low frequency wave are different.The best vibration frequency and amplitude are 10Hz and 100m respectively.It can be seen that low frequency pulse wave can improve the porosity and permeability conditions of low permeability reservoirs and fluid seepage environment to a certain extent.The research has a certain theoretical significance for the application and promotion of low frequency fluctuation technology in the field.