The Study On Non-destructive Testing System For Oil-well Tubing Defects

At present the pumping tubing used in oil wells is working under poor conditions. Long time use often causes problems as corrosion, wear and tear perforation, rupture or even fracture, etc. And the problems do not always expose themselves, so production accidents happen easily under this situation to cause injury to the stuff. Therefore it is extremely necessary to develop inspection equipments of fast detection of defects in well tubing and without damaging the tubing itself.A non-destructive testing system is designed to solve the defects problems in oil-well tubing. And the new magnetic detector for inspection of defects in oil-well tubing is used to acquire signals, and then the signals are magnified, A/D conversed, and then transferred to PC through wireless receiving model ZigBee for easier operation. Meanwhile, Software C++ Builder6 is used to produce a host computer interface and a variety of oil-well tubing defects can be displayed in real-time.The whole system is divided into four parts, namely, Signal Acquisition, Signal Processing, wireless communication and real-time Display. In order to increase the speed of communication with the PC and to obtain accurate real-time display, a USB interface chip CH375 is used to make the signal processing part as a USB device, in this way communications with PC is built up through Universal Serial Bus. The currently most used ZigBee chip CC2420 is utilized to realize wireless communication function. And the rest three parts still run as a complete system when wireless communication is not working. When there is a far distance from the host computer to the lower computer, the wireless communication module will be put in between. And the wireless communication is under modular processing and it is also USB communication mode. The plug and play function offers great convenience to the use on site. An enhanced 51 single-chip STC12C5404AD is used as a system microcontroller.The paper analyses in detail the principle and composition of the above- mentioned parts. It meets the design requirement and the products are made to be proved on site that the system can detect fast and accurate various defects in oil-well tubing and that it is easy to operate. Moreover, this paper has laid a good foundation for the improvement of the products.