Research On The Key Technology Of The Launch Circuit Of The Array Laterolog System

With oil and gas exploration goals gradually turn to complex reservoirs,and the difficulty of oil and gas development continuously improve. The dual laterolog become difficult to meet the new demands of fine oil and gas exploration because of the logging more and more precise analysis and evaluation of formation. Based on the dual laterolog, array laterolog tool is developed. With multi probing depth,array laterolog has incomparable advantage in thin-layer evaluation and formation invasion characteristics, oil and water identification, reserves estimation, etc, it is a Advanced instruments in evaluation of thin and deep formation. Although there is some domestic enterprises successfully developed the array laterolog tool prototype, but the development of array laterolog with independent intellectual property rights still has great significance and economic value.For the background of develop array laterolog Prototype,this paper main discuss the key technology of launch system of the array laterolog. Because the logging instrument working in harsh high temperature environment, and low power design requirements, logging instrument emission control circuit abandoned FPGA based on SRAM technology and choose FPGA based on Flash.This paper will introduces how to enable microprocessor-based embedded remote ISP(in-system programming) on the logging instrument’s FPGA based on Flash。The platform hardware circuit is designed with the TMS320F28335 DSP as the core control device, developed to implement A3P400 in system programming base on JTAG principle.In addition, according to the measured formation resistivity changes a lot, dynamic range of received signal is very large and the signal is also very faint,a 4-channel sinusoidal signal generator is designed of high signal to noise ratio,in order to reduce the dynamic range of the receiving circuit requirements. In this paper, two multi-channel sinusoidal signal generator based on different principles were used,one of which is based on PWM on the DSP device and Another is design with FPGA and low-pass filter based hardware platform used CORDIC and Delta-Sigma modulation. By spectrum test the spurious-free dynamic range of the design meet the requirements. All work finished have lay the foundation for the development and production of the array laterolog tool.