A Research On The Feasibility Experiment Of Nanhai M OilfieldWater Injection

Because of the complex geological reservoir characteristics,much faults and strong longitudinal heterogeneity,complex plane connectivity and insufficient energy supply,the formation pressure has decreased greatly and the production has decreased rapidly since Nan Hai M oil field was put into operation.In order to improve the development effect,water injection is urgently needed to replenish formation energy.It can provide theory and basic parameter for the water injection project design of the oilfield through feasibility research of water injectionBased on the reservoir characteristics and injected water quality of Nanhai M Oilfield,this paper has carried out a series of studies,such as reservoir physical properties analysis,reservoir rock characteristics analysis,water injection quality analysis,reservoir injury evaluation,formation analysis of water injection scale formation and scaling trend prediction,screening experiment of injected water treatment agent,calculation and analysis of formation water absorption capacity.Through the research of this project,the following main conclusions are drawn:the water B of water source well is more suitable for water injection for target layer of M oil field than that of water source well A.Sterilization treatment is needed in water treatment;under 25-60?conditions,injection water for water source well water can B meet the injection anticorrosion requirements of N80 steel;seawater has a small corrosion effect on the pipeline at 25?.However,as the temperature increases,it may lead to pipeline corrosion,which cannot meet the injection requirements and requires corrosion inhibition.Through the scale prediction and analysis,it is concluded that the source well water B is more suitable than the source well water A and seawater as the injection water source,and the priority order of selection is as follows:source well water B>source well water A formation water>seawater.Through the experimental analysis of velocity sensitivity and water sensitivity,it can be determined that the target layer of M oilfield has the characteristics of weak velocity sensitivity and strong water sensitivity.The injection of two source Well water and seawater will not cause strong sensitivity damage,but it will cause serious damage when low salinity water enters the formation but will cause serious damage when the low-salinity water enters the formation.The critical injection flow of target layer is 5ml/min and the injection flow rate should not exceed 80 m/d.The target layer has a high water absorbing capacity and needs a small injection pressure.No matter how small the injection pressure is,it will cause damage to the formation permeability.The recommended injection volume of target layer is 134-156m3/d,and the critical injection volume is 178m3/d.Based on this research,a set of water injection quality index suitable for M oil field is established,the influence factors of reservoir injury,the influence factors and mechanism of water injection scaling are studied,and the parameters of water injection process are studied and designed.It can not only provide the basis for water quality treatment,but also provide theory and basic parameter for reservoir protection and water injection development scheme design.