Study On Bidirectional Wireless Pressure Wave Communication In Water Injection Wells

At present,the most economical,efficient and potential technology in the field of oil field development is stratified fine water injection.Layered water injection can effectively control the oil-water ratio of oil production wells,improve the oil recovery rate of the oil field,make the oil production of high output of the oil field,maintain the stable output of the oil field,and improve the economic benefits of the oil field.However,with the development of layered water injection technology,the number of layered water injection wells in oil field is increasing year by year,which leads to the increase of the workload of water injection well measurement and adjustment.At the same time,due to the long interval period of testing and adjusting,the qualified rate of water injection can't be maintained for a long time.Therefore,this paper proposes a two-way wireless communication method based on the pressure wave of the string.The data transmission process does not need to stop water injection,so as to ensure the continuity of layered water injection process.At the same time,real-time measurement and adjustment can also reduce the workload of manual measurement and adjustment.Through the wireless communication method based on the pressure wave of the string,the wellhead control equipment and the downhole water distributor can control the flow and pressure of layered water injection and collect the data of the flow and pressure of downhole water injection in real time.Firstly,the transmission dynamic characteristics of pressure wave pulse signal in water injection pipeline are studied.The calculation method of the transmission speed and the water hammer pressure of the pressure wave signal in the transmission process is discussed.At the same time,the amplitude frequency characteristics of the pressure wave signal are studied,and the main factors that affect the attenuation of the signal in the process of pressure wave transmission are analyzed and simulated.According to the attenuation law of the signal,the measures to improve the transmission speed and reduce the attenuation of the signal are proposed.Secondly,according to the transmission characteristics of pressure wave signal in the well,the format of pressure wave communication data frame is defined,including start bit,function bit,layer bit,target information bit,data bit,stop bit and check bit.Based on the Manchester coding and decoding,the pressure wave control layered water injection method is formed.At the same time,according to the characteristics of the received data,different filtering methods are compared,and filtering methods suitable for pressure wave decoding are designed.Finally,the hardware of the ground controller is designed and manufactured,which is used to send control instructions from the wellhead to the bottom of the well and receive real-time data from the bottom of the well.The software of computer upper computer is developed.Through communication with ground control equipment,the computer upper computer monitors the water injection information such as flow,pressure,temperature,etc.collected in real time from the well,on the one hand,and indirectly sends the water injection control instruction to the water distributor in the well through the wellhead control equipment on the other hand.Using the developed hardware and software to simulate the well experiment in Jidong Oilfield,the experiment shows that the communication between the wellhead control equipment and the downhole water distribution device is realized through the wireless communication method based on the pressure wave of the string in this paper,which can be used to control the flow and pressure of layered water injection and distribution at the wellhead.