Research On Key Techniques Of Segmented Bond Tool And The Implementation

The acoustic log is an effective method to examine the condition of the cement bond; the segmented bond tool is not affected by many conditions down hole, which is seriously degrading other cement evaluation devices. By measuring the correlative parameters of first-arrival, SBT can check whether the well is well cemented or not. With the development of the project, three key techniques are thoroughly investigated, that are data acquisition, down-hole first-arrival detection and single conductor channel equalization, and then the electronic circuits are developed.Data acquisition module whose parameters are changeable is designed, which enable the tool to change the sampling parameters according to the surface system's command.Through the research of first-arrival detection methods using by surface system, a method based on the long window-short window energy ratio is chosen to pick the first-arrival. In order to increase the veracity of the detection, the FIR filter is designed on FPGA by the method of decreaseing the intensity of operation, and then used to increase the SNR of digited waveform.Manchester code will be distorted when it is transmitting though the cable. In order to ensure the validity of the transmission of the system, a model of single conductor is designed depending on the transmission line theory and the research of the transmission characteristics. Then the equalizer is designed based on that model, using PSpice emulation tools.The experimental results shows that the tool can complete the entire task and the aims are achieved.