Experimental Study On Ultrasonic Treatment For Rremoval Of Near Wellbore Damage And Technological Parameters Optimization

With the development of oilfield exploitation and production,recovery difficulty and cost of land oil increased.At the same time,it becomes more and more difficult to carry out the harmonious development of oil production and ecological environment,so it needs high efficient and environment friendly EOR technologies.Ultrasonic treatment for removal of near wellbore damage is one of those technologies.But theoretical study of this technology is lagging behind process technology seriously,this makes field construction blind and the effect unstable.Focusing on those problems,this paper developed the following research work.First,we founded mathematical models of fracture generation mechanism,fluid adhesion layer elimination,depolymerization etc.Then by means of coupling wave field, seepage field and soild medium field,we set up theoretical models of particles bridge formation and particles deposition onto the pore walls,after force analysis and model solution, the dynamics conditions of ultrasonic treatment for removal of near wellbore solid particles damage was obtained.Using the multifunction dynamics simulation system of fluctuating oil extraction technology,we have carried on experiments of ultrasonic treatment for removal of polymer plugging,precipitation of paraffin, drill fluid damage,inorganic scale plugging and water sensitivity of cores. Influencing factors of ultrasonic removing formation damage was founded,as well as its influence rules.Finally we compared the effect of plugging removal by ultrasonic single,chemical single and composite members,and effect of the composite one is better,this because that ultrasonic and chemical have synergetic effect.By comparison of theoretical results and experimental datas, they agreed well with each other.Based on the study of theoretical and experimental research,we optimized the ultrasonic parameters,and established the standard and principle of well and layer selection.Those all provide theoretical and experimental basis for ultrasonic treatment for removal of near wellbore damage in the field application,it helps to ensure the implementation effect and success rate.