Study And Realization Of Water Cut Detection Method For Crude Oil By Conductance Method

With the continuous exploitation of oil resources in China,most oil fields have entered the stage of high moisture content exploitation.In order to achieve stable production and increase the recovery rate in the high water-cut stage,high-pressure water injection is required in the underlying reservoir.Long-term high pressure water injection can lead to some sections of the well water content surge,which needs to effectively seal the section.In this way,it is very important to measure the moisture content of each layer accurately.In order to adapt to the modernization of the oilfield,it is necessary to realize the real-time measurement of water content in the well,avoid the waste of human and material resources caused by the measurement on the well,shorten the measurement and adjustment period and provide the correct water content data for the oilfield development decision,which is the important significance of the design of the water content measurement system in this paper.Firstly,by studying the background and status of water content detection technology,it is found that the method of measuring water content of crude oil based on conductivity method has the characteristics of simple hardware structure,stable and reliable system and accurate measurement.According to the principle of maxwell model,the conductivity of pure water phase should be known when determining the moisture content of crude oil by conductivity method.However,the conductivity of downhole pure water phase cannot be directly obtained when real-time underground moisture content measurement is carried out,and the dynamic characteristics of moisture content of downhole crude oil cannot be characterized in real time by pre-set conductivity value of pure water phase.According to the above problem,this paper,based on the fraction of crude oil properties,by measuring the conductivity of the two groups of oil-water mixture under different temperature phase value and further expression derived oil moisture content,avoid water phase conductivity test question and the preset water phase conductivity impreciseproblems,realize the existing crude oil moisture content measurement method is improved.Secondly,in order to verify the above methods,the software and hardware of moisture content system are designed.Build hardware system based on ARM cortex-m4 processor.It mainly includes core controller minimum system module,excitation module,signal acquisition and measurement module,data transmission module and power module.The software system is divided into upper computer and lower computer design,the main function of the upper computer is to receive the data transmitted by the lower computer and used for display,analysis and storage,the main function of the lower computer is to measure the water content of the data and send it to the upper computer.Finally,the above method is used to measure the water content in the well.The experimental results show that the error of moisture content is less than 2% when the moisture content is more than 90%.When the oil-water two-phase flow with the pure water phase salinity within 7g/L is measured,the moisture content error is not affected by the salinity.The experimental results verify the effectiveness of the optimization method and the feasibility of practical application.