Ultrasonic Detection Technology And System Development Of Wellbore Leak

Due to the complicated geological conditions and harsh downhole conditions,in natural gas mining process,tubing wall,casing wall,thread connection and downhole components are easily damaged by corrosion,aging and various stresses,which result in wellbore leak.Once the leak occurs,the leak will be aggravated with time,which will cause damage to the tubing and casing.The consequences of damage is to pay tens of thousands of yuan for repair,and even cause serious leak accident and natural gas well scrapped.The earlier the leak point is found,the more it can reduce the repair cost and avoid the accident.In order to find out the early tiny leak of natural gas well,a leak detection system based on passive ultrasonic propagation measurement is designed according to the ultrasonic propagation characteristics of fast attenuation and good directivity,which includes the design of signal processing,signal acquisition and communication,circuit board and instrument structure.In terms of signal processing,the amplification and filtering measures are taken for the extremely weak ultrasonic caused by leak,and the countermeasures are put forward for the input noise of the system caused by signal connection,which further improve the signal to noise ratio of the measuring circuit.In terms of signal acquisition and communication,the port configuration of the selected single chip computer is carried out,and the program of the lower computer is developed.In terms of the circuit board and instrument structure,the measurement environmental influence on the circuit components and the structure of the instrument are analyzed,the selection criteria of components and the considerations of the design details of the circuit board and the instrument structure are put forward.In order to evaluate the measurement performance of the leak detection system,an experimental system for simulating the leak of the wellbore is built.The small leak of tubing and casing is simulated by the wellbore simulation device.In the leak test of the tubing,leak detection system can not only detect the occurrence of leak,but also accurately determine the leak location.In the leak test of the casing,the leak detection system detect the occurrence of leak,but the location of the leak is not accurate enough.The test results show that the leak detection system can detect and locate the wellbore leak,which achieves the basic goal of design and has the basic conditions for field application.