A Study On Diagnosis And Evaluation For Near Wellbore Formation Damage To Injection And Production Well In Jiyuan Oilfield

The chang8 reservoir of Jiyuan oilfield is extra low permeability reservoir,poor physical property,strongly heterogeneity.It is more vulnerable to suffer damage near wellbore formation to injection and production well in the development.X-ray diffraction,scanning electron microscopy,casting thin sections,pressure mercury injection experiment and other technical means were used to analyze the rock properties and physical properties of reservoir core.It is concluded that the main clay mineral is feldspar,kaolinite,illite.Reservoir is holes,low permeability reservoir which has complex pore structure.Potentially velocity sensitivity,water sensitivity and acid sensitivity damage is existed in the study reservoir area.Combined with the indoor flow sensitivity experiments to determine the acid sensitivity is major potential damage factors in the study area.The reservoir fluid and injected water assay analysis results show that the formation water contains calcium,barium strontium ions,bicarbonate ion and injected water containing sulfate ion which is not compatible.Calcium carbonate and barium sulfate scaling trend are serious by means of scaling prediction.Finally,the prediction result is comfirmed by water and formation water static compatibility experiments and dynamic core damage experiments.The comprehensive analysis of pollution factors of Chang 8 reservoir in Jiyuan oilfield indicates that the imcompatibility of injected water with formation water is the leading cause of the pollution of near well formation of injection well.Oil wells were blocked with calcium carbonate and particle migration caused by acid sensitivity.According to the results,proposed preventive measures for pollution of Chang 8 reservoir in Jiyuan oilfield.Electrical pulse was applied to injection wells,and acidification was applied to oil production wells,putting forward the the acetic acid as leading acid.Field test results show that the measures are effective,and to be able to effectively discharge reservoir restriction.