Study Of Ultrasonic Flow Measurement Technique Methods

Lost circulation often happens in the process of oilfield drilling construction.It is harmful and not easy to deal with among all the downhole engineering accidents.Serious lost circulation may not only waste drilling fluid,but also cause damage to oil reservoir,pollute the underground environment and affect the progress of normal construction.If the lost circulation gets worse,it may cause borehole collapse or blowout accident.When lost circulation seriously affect the normal drilling,effective measures should be taken to detect and plug the leakage zone.The plugging time is also uncertain because of the uncertainty of the determination of leakage zone.Currently,the oil fields are in urgent need of efficient and reliable leak detected instruments and techniques to locate the downhole leakage zone and ensure the normal construction of oilfield.The influences of different factors such as the fluid properties,the installation conditions of ultrasonic sensors on measurement results for existing underground flowmeters based on the predecessors' research have been analyzed in this paper.A set of ultrasonic flow detection system which was based on the time difference method aiming at downhole leakage well was designed to detect the downhole leakage zone.The system includes hardware parts such as ultrasonic transducer which is made of piezoelectric ceramics,high precision time difference method of velocity measurement circuit,wireless communication module and software parts such as underground system measurement program and upper computer program and so on.The downhole velocity parameters acquisition can be carried out by the hardware circuit.The ground wireless communication system was designed to obtain data in the field in remote communication.According to the functions' requirements,a set of upper computer program was designed by using LabVIEW software to realize functions such as the configuration of serial port,the recording of depth,curve drawing of velocity and depth and so on for the data interpretation.Integration tests and static water simulation experiments were carried out after the debugging of software and hardware modules.A set of fluid circulated experiment platform was set up to perform interior simulation experiments under different kinds of conditions.The experiments' data processing and analyzing were also carried out.The experiment results showed that the ultrasonic flow detection system designed can work stably and it can effectively detect the change of flow velocity.The data interpretationand detection of leakage zone can be direct and reliable after drawing the curve of velocity and depth by using the upper computer designed with LabVIEW.This system can help improve the efficiency of leak detection and plugging and ensure the normal schedule of oilfield construction.