The Design Based On CPLD For Control System Of G-ray Pedigree Well Logging

Nature gamma ray pedigree petroleum well logging is an instrument which can measure the gross content of natural radioactive element and the percent of such element as uranium, thorium, potassium in the stratum. The content of uranium, thorium, potassium is 99% of the whole natural radioactive element, while others is less 1% and can be ignored. According to the chemical properties of uranium, thorium and potassium, the existing law can be obtained by analyzing the information from the nature gamma ray pedigree petroleum well logging and other correlative data. Using this law, we can identify igneous rock, distinguish the shale, determine the content of clay, and plot out the storage layer. The sediment surroundings can be estimated by comparison the penetrability and throughput of storage layer, and then the geological problem in petroleum exploitation can be solved.Nature gamma ray pedigree petroleum well logging is mainly composed of crystal, photo multiplier tube, preamplifier, high voltage multiplier and signal processor. 50μCi of Am241 is right near to the crystal. The signal processor is composed of the part of measurement and pedigree stabilization, plugs. The design of the circuit include the design of circuit signal amplifier, comparable logical circuit, pedigree signal comparable logical circuit, high voltage circuit control and pedigree error control, transmission of energy window's rate and the circuit of plugs.In this dissertation, MAX+PLUS II development system, which was developed by ALTERA company in US, was used as design environment. MAX+PLUS II development system is an integrative, wieldy and programmable design environment,The design in this dissertation was based on the existing instrument, which entered the market more than 20 years ago and been accepted by the consumers and which had mature and reliable circuit design, so the improvement of the design was on the basic of the existing design. The design principle and the function of the circuit was the same, but function was realized by using advanced technology and the level of the instrument was heightened. In this dissertation, the design, improvement and debugging of the hardware circuit was finished and the corresponding experiment had testified that the instrument with new design could work steadily and had good linearity, and the expected purpose was achieved.