Study On Adaptability Between Suspended Particles In Injection Water And Reservoir Formation

Water flooding production is one of an important form in development of the oil filed,79%of Shengli Oilfield is water drive reservoir,which are generally in the face of higher injection pressure along with low permeability reservoir development which lead to low capacity of water injection and difficulty of production energy supplement.Therefore,this paper is supposed to explicate the influence factor and rule of injection pressure by studying adaption between suspend particles and reservoir,intend to provide some theoretical support to water injection in oilfield.This paper based on the phenomenon of suspend particles movement in porous media,combined with filtration theory,fluid factors and physical property of porous media are considered to constructed suspend particles movement model in porous media.NMR method was used to measure pore size distribution,then constructed numerical simulation with the method of numerical difference and programmed a software to run the simulation.After series of experiments,simulation results are adjusted to reflect the reality.The particle diameter,particle concentration,injection rate,porosity,permeability and length of core are studied to find the influence of these factors on injection pressure.Multi-factor analysis is used to confirm the main controlling factor.The research find that while suspends particles are retained in the porous media,the porosity must decline,the circuity of pore must increase and the quantity of flowable pore must decrease,therefore,permeability of porous media must reduce,then give a rise to injection pressure.Injection pressure is influenced by particle diameter,particle concentration,injection velocity,length of porous media,porosity and permeability.For Al₂O₃ suspend particles,the optimum particles size should be less than 10%of average pore size of porous media,the optimum particle concentration should be less than 16mg/L,so that injection pressure would increase not too much and plugging rate would less than 5%.Injection velocity and length of porous media have little effect on the increase of injection pressure and plugging rate,but it effect the increase speed of water injection pressure,it's better to keep a lower injection velocity and length of porous media.Suspend particles are more easier to retain in porous media when porosity and permeability of porous media are lower,particle diameter should keep less than 1?m when porosity less than 15%and permeability less than 2mD.From large to small,the impact of each factor on the plugging rate are written as:particle diameter>porosity>permeability>injection velocity>length of porous media>particle concentration,particle diameter is the main control factor of plugging rate,the key to control injection pressure is to control size of suspend particles.