Research On Key Technology Of Wireless Fluid Wave Code For Layered Injection Equipment

In view of the annual increase of injection Wells and the demand for accurate data,Petrochina has formed the fourth generation of stratified water injection technology represented by wire-controlled type and wave code communication during the 13 th Five-Year Plan period,which realizes real-time monitoring and automatic deployment of water injection data in strata.As one of the fourth generation of main injection technologies,the wave code injection process is widely used in injection Wells with pressure operation in low permeability oil fields,which has the advantages of simple operation and low cost.However,there is a problem of low communication efficiency,and it takes 2.5 hours on average to transmit a group of layer segment data wirelessly.The study shows that the main factor that affects the real-time monitoring of injection data is the efficiency of data transmission,and the main problems that cause the long time of underground data transmission are the encoding and decoding method and the high threshold pressure pulse.Based on the above engineering background,this paper carries out the following research:Firstly,the principle of the wave code injection process and the development of a wave code layered water injection device are introduced.In order to meet the requirements of rapid pressure pulse generation in the underground,the high-speed pulse switch actuator is designed with pressure balance,so that the driving force provided by the motor is only used to overcome the friction caused by the signal stem to realize the dynamic seal.Secondly,the transmission mode of pressure wave and the transmission characteristics of pressure wave in the transmission process were deeply analyzed,and the relationship between the transmission speed of pressure wave in the transmission process and the closing time of the valve was discussed.The intensity problem of pressure wave is studied,and the signal attenuation during the transmission of pressure wave is analyzed and simulated.According to the transmission characteristics of pressure wave in the wellbore,the communication protocol of wave code injection process is defined.By comparing amplitude time modulation and pulse position interval modulation and coding,a coding and decoding method based on pulse position interval is designed.Thirdly,aiming at the problem that the threshold pressure set value is too high,the temperature compensation algorithm of the pressure sensor is studied,and an adaptive filtering algorithm based on wavelet transform is proposed,and the original pressure pulse data collected in the field are filtered.Finally,the test of the encoding and decoding method and the method of reducing the threshold pressure were completed,and further tests were carried out through indoor comprehensive experiments and field operations.The test results show that the downhole communication equipment works stably and reliably to meet the design requirements.After the proposed method,when the pulse width is set to 5 seconds,the time used to transmit a single data is reduced from 40 minutes to 3 minutes,and the decoding success rate is 80%.The transmission efficiency of downhole data is improved,and the real-time monitoring of injection data and the automatic allocation of injection water are realized.