Design And Development Of Azimuthal Electromagnetic Wave Resistivity Logging Instrument While Drilling

Azimuthal electromagnetic wave resistivity logging instrument can be used to implement formation resistivity test,while its orientation in formation can be estimated precisely.In this case the path of wellbore can be kept in reservoir,which will decrease cost of exploration and development through this technology.The working theory of the azimuthal resistivity logging instrument and corresponding prototype were introduced in this thesis.According to the propagation characteristics of electromagnetic wave,the influence of coil parameters on drilling responses was analyzed,meanwhile,the key structural parameters of coils such as distance between transmitter and receiver,distance between receivers,working frequency,angles of inclination coils were determined,which based on measure requirements and various constraints.The logging instrument will be faced with several impacts such as surrounding rocks and formation interface during the drilling.In order to analyze above impacts,finite-different timedomain as the forward methods was applied in this thesis.First of all,the effects of drill collar,borehole,invaded zone,borehole inclination angle on logging responses were discussed by the methods of control variables.In addition,In contrast with the traditional response signal,a new directional signal was developed.This directional signal had the capabilities of formation evaluation as well as geosteering.According to numerous of simulation results indicate that azimuthal resistivity logging instrument have excellent capabilities to estimate relative position with formation interface and forecasts the distance to the interface.Based on the coil parameter designing principles,a trial production of prototype has been accomplished in the laboratory.The prototype hardware include transmitter module,receiver module and control module,and the core circuit include: the power amplifier,the voltage amplifier of receiver signal,filter,and LC resonance network.The prototype software include the detection methods of amplitude ratio and phase difference,and DSP-FPGA collaborative works.The orthogonal sampling methods was used to calculate the receiver signal amplitude radio and phase difference was introduced in this thesis,according to the comparison between simulation results and experimental results to verify the function of the prototype.In order to test the performance of the prototype,a metal ring which known resistance was designed as a calibrator.According to the comparison between simulation results and experimental results,the function of the prototype was verified and calibrated.And then,a strata model which is simulated by salt-water was designed to test the sensitivity of the prototype for detecting the formation interface.And the test results were satisfactory,which is a good basis for the subsequent development of real logging products.