An Experimental Research On Stimulation Of Injection Well With Surfactant In The Low Permeability Oilfield

the reserve of low permeability reservoirs has become an important part of petroleum resources in our country. Most of the low permeability oilfield in China is mainly waterflooding development approach.The physical properties of low permeability reservoirs are usually different from common reservoirs,and pore small, low permeability and large flow resistance are commonly found in low permeability reservoirs.In addition sensitive minerals are in the reservoir and the injection of water is not compatible.These factors cause great damage to the formation.The injection pressure is increasing and the injection rate is reducinge.Furthermore, the scope of the common fracture and acid is small and the effective time is short.Surfactant associated with water injection to deal with larger radius,surfactant flooding in high permeability reservoirs has achieved good results.So the study of surfactant flooding in lowering injection pressure is significant to the development of low permeability reservoirs.In this paper, laboratory experiments as a means of water flooding characteristics in low permeability reservoir were studied.The interfacial tension is the main evaluation index of the surfactant used for reducing injecting pressure.The concentrations of surfactant,salinity and pH on interfacial tension behaviors are investigated.Carried out chemical flooding to reduce injecting pressure tests,evaluated the influence of surfactant flooding in low permeability reservoirs.Also,the surfactant slug size,injection rate and injection opportunity on reducing injecting pressure are investigated.Research indicates that surfactant flooding can reduce the injection pressure of lowpermeability cores,improve the two phase flow characteristics,increase the relative permeability of both phases,widen two phase flow region Detection results exhibit that with the increase of the surfactant slug size,the lowering injection pressure effectiveness rises,which decreases with the injection rate.There is a best parameter combination in surfactant flooding. surfactant concentration of NS-1 is 0.5%, the best injection volume is 1PV, the optimal concentration of surfactant SR -J3 is 0.3%, the best injection volume is 1PV.