Research On Signal Launch Technology Of The Resistivity Imaging Logging While Drilling Instrument

The resistivity imaging logging while drilling is a basic tool for modern formation evaluation.By recording the micro-resistivity around the well wall we can provide the formation and lithology characteristics of heterogeneous reservoirs and carry out structural analysis and fracture analysis and reservoir analysis.This paper mainly focuses on the research and design of the launching part of the resistivity imaging instrument while drilling.In this paper,on the basis of the reference to the principle structure of foreign drilling wall resistivity imaging logging tool,the spiral coil structure that constitutes the signal transmission device is studied in-depth.The core parameters and the coil winding on the spiral rings and its electrical performance are analyzed.find the most optimized launch spiral design.A signal transmission circuit board for driving a spiral loop is designed and manufactured and a direct frequency synthesizing technology is adopted to realize the modulation and control functions of a signal source through DSP and DDS and a signal with sufficient drive capability is generated for driving a spiral transmission loop.In order to achieve the versatility of the transmit circuit the circuit is designed as a signal emitter with a frequency adjustable from 0 to 2 MHz an amplitude of 0 to 20 V and an adjustable phase.In order to verify the practical function of the launching spiral loop and the signal transmission circuit,an experimental system for a simple simulation of the electric imaging instrument for drilling was first designed in the laboratory and the entire instrument system was simulated and tested to obtain the measurement of the resistivity of the simulated formation.Data by analyzing the data finally verified the practicality of the experimental device and the transmitting circuit.