Study On Key Technologies Of Main Control Circuit Of Azimuth Array Lateral Logging Tool

At present,oil exploration and development in various countries have stepped into tight sandstone,carbonate rock and other difficult reservoirs,and the thin layer and high-steep structure make the reservoirs show strong anisotropy.The azimuth array lateral instrument can not only detect multi-radial depths,but also image the azimuth resistivity of strata around the well,which is a great weapon to solve the complex geological evaluation problem at present.The design of the main control circuit of the instrument is the central part in the development of the azimuth array lateral instrument.The design level of the software and hardware of its internal units such as signal transmission,response signal acquisition and control,data processing and operation will determine the measurement performance of the instrument,so it has high research value.The main work and achievements of this thesis are as follows:1.Based on the lateral logging theory,on the basis of analyzing the functional requirements and performance indexes of the main control circuit of the azimuth array lateral instrument,the main control system is studied based on the control operation architecture of DSP+FPGA.2.Aiming at the problem of poor logging signal quality from logging tool,a DDS high-precision signal generator based on improved CORDIC algorithm is designed and implemented.This signal generation method can effectively improve the system running speed and signal emission quality while saving chip resources.3.A complete and efficient multi-channel signal acquisition and data processing system is designed and implemented in the order of collecting and processing response signals by instruments.By optimizing the calculation flow of radix-2 FFT,the data operation speed of the main control circuit is obviously improved.4.Aiming at the phenomenon of power deviation caused by the traditional power control method of the instrument,an adaptive power control method is proposed,so as to realize a wider measurement range and higher accuracy of the instrument.Single-board test,system debugging and other tests show that the circuit can meet various functional requirements and index requirements,and can withstand the high temperature environment test of 180℃/12 h.The calibration linearity test proves that the azimuth array lateral instrument equipped with the main control circuit can maintain a good linear relationship in the dynamic range of 3.6Ω～180kΩ,and the measurement error is far less than the instrument index.The field downhole experiment finally proves that the instrument can successfully distinguish thin and anisotropic geological structures with high vertical resolution,and the adaptive power control method is effective and feasible.The research work in this paper provides theoretical and technical support for the development and application of azimuth array lateral instrument.