The Design Of Near Probe Acquisition Module Of 3D Acoustic Logging Tool

The design of acquisition module of three-dimensional acoustic logging tool, which is close to the probe, is the subtopic of the national 12 th five-year major project, named the research of three-dimensional acoustic logging tool technology. In order to enhance our technology on acoustic logging technology and reduce the cost of the introduction of relevant technology and equipment, independent research and development of three dimensional acoustic acquisition system become very important. Actually, the logging instrument works in bad environment. And the acoustic signal which represents the information of earth is weak. In order to ensure the accuracy of logging, multi-channel sampling and a variety of modes is necessary. However, uploading a big amount of data leads to the logging time eventually;It is difficult to parse and perform the command stably.In order to solve these problems, this dissertation mainly elaborates the design and implementation of the acquisition module of three-dimensional acoustic logging tool on the basis of predecessors’ technology. It mainly includes weak signal detection technology, high speed serial data transmission technology, high temperature PCB design technology, mine communication protocol and the realization of the control logic. Weak signal detection techniques mainly includes the design of low noise signal conditioning circuit and the design of high precision acquisition circuit. Low noise signal conditioning circuit ensures the effective acoustic signal to be received, and the high precision acquisition guarantees the analog-to-digital conversion signal is accurate. What’s more, the dissertation focuses on the noise analysis and calculation from each sub-module to the whole module, in order to reach the goal of reducing noise. High-speed serial transmission technology mainly deals with the interface technology and the sampling data recovery technology. And it is realized based on an LVDS. High temperature PCB design technology focuses on improving some chips and local heat, which makes the whole acquisition boards work stable in high temperature environment. The realization of the control logic focuses on the design of underground communication protocols, and the implementation of the acquisition command parsing and the control logic of acquisition system.Through the main technical research and the implementation discussed in the above, the acquisition module,which can work under the environment of high temperature is designed. It is able to detect and converse weak acoustic signal, and parse acquisition command and control the whole system correctly and stably. Through the high temperature veneer, system alignment, flume experiment in the laboratory and the well field experiments, the acquisition module designed in the dissertation achieved the desired technical index.