Design And Implementation Of Electromagnetic Detection Signal Source In Well Logging

In the development of underground resources and geological prospecting,electromagnetic wave logging is an important means to obtain formation information;among them,there are two important detection methods in electromagnetic wave logging,one is the carrier-free pulse radar system in a single well,and the other is a cross-well electromagnetic system between two wells or multiple wells.This article will discuss the design and implementation of the emission sources of the two systems.The emission source used in the carrier-free pulse radar system is a bipolar Gaussian pulse,which has the characteristics of high instantaneous power,large bandwidth,and high amplitude;in the design of this article,the unipolar Gaussian pulse is mainly generated by an avalanche tube Pulse,and increase the pulse amplitude through Marx cascade,use reflection line coupling to generate bipolar Gaussian pulse,and use the switch gating method to design to produce four frequency adjustable double Polar Gaussian pulse source,and finally realized the width is less than 35 mm,the length is about 50 cm,50MHz,100 MHz,150MHz,230 MHz four frequencies adjustable pulse source,and the amplitude of each channel is above 800 V,and the tails are all within20%,the bandwidth of the four pulse sources is greater than 50M;This pulse source can change its center frequency without raising the instrument to the ground.In the field of cross-hole electromagnetic,due to the cross-hole logging and its long distance,the requirement for the emission source is to have sufficient power;the cross-hole electromagnetic emission source designed in this article converts the DC power into the sinusoidal alternating current is applied to the transmitting coil to realize the design of a high-power transmitting system,and finally a transmitting source with a width of less than 33 mm and four transmitting frequencies of 15.625 Hz,125Hz,500 Hz and 1k Hz is designed,and the test results are It shows that when the frequency is15.625 Hz,when the applied DC power is 35 V,the emission current loaded on the coil can reach 1A,which can meet the requirements of the entire system for cross-well electromagnetic detection.This signal source realizes a small size for the first time,Emit magnetic signals downhole.This article will explain the design of the two emission sources from the background and significance of the topic,the overall scheme design of the system,the selection of key components,the determination of key parameters and the simulation of key parts,and the design of each type of emission The source conducts a final performance test.