The Design Of The Master Control System Of Multi-Parameter Combinatory Logging Instrument

The logging instrument, which is designed by using a combination of induced polarization, spontaneous potential and formation water resistivity, could implement inter-compensation among the parameters when logging interpretation. It is beneficial to implement stratigraphic inversion. Compared with the traditional logging, it could obtain more accurate relative parameters as for instance in formation water resistivity and polarizability. And it is of great significance to evaluate the flooded layer of oil filed and solve the remaining oil saturation. Master control system, as the core of the logging instrument, whose performance directly affects the access of multi-parameter and the realization of combination logging.Based on the study of the principles of three kinds of electrical logging, according to the differences, the thesis proposes a combinatory logging method, which could implement three different kinds of methods by one workflow dependence on the precise control timing of the master control system. Taking Digital Signal Processing (DSP) and Field Programmable Gate Array (FPGA) as the master controller and the associate controller, respectively, the master control system implements multi-channel sample processing and exchanges information with the ground control system in the form of CAN message by CAN Bus. Not only the circuit of the main control system, but also the specific method of the software, is introduced. A bus controller and an interrupt controller are designed in the FPGA which is used as the peripheral of the DSP. All of those make the two work together to generate the control sequence and transmit the data. By using star design structure and modular design approach, the software has high flexibility. And it which has been designed in the parameter-control mode could real-time adjust the timing by changing the parameters of the FPGA controlled by the DSP. In addition, some averagers are designed in the FPGA to preprocess the sampled data, so, the signal-to-noise ratio (SNR) of the system is improved effectively. Finally, the electrochemical experiment platform is built in the lab. According to the simulation experiments of induced polarization logging, the features and performance of the system designed have been proved. The experimental results indicate that the combinatory logging instrument operates with high stability, precise control sequence, high accuracy. All of those reach the design target of the combinatory logging.