Research On Antenna Structure Of Sweep-Frequency Dielectric Logging Tool

Sweep-frequency dielectric logging based on rock dielectric dispersion not only inherits the advantages of traditional dielectric logging,but also overcomes the limitations of dielectric logging and provides more accurate information for formation rock physics evaluation.Although great achievement on dielectric logging has been reached in China,the research on sweep-frequency dielectric logging is still at its beginning,and there is still a long way to go to achieve localized production of instruments,especially for the tool's antenna whose structure still needs to be optimized and improved.Therefore,it is necessary to carry out theoretical research and numerical simulation of the antenna structure of the sweep-frequency dielectric logging tool.In this paper,we first introduce the relevant principles and design requirements of the sweep-frequency dielectric logging instrument antenna,and then introduce the workflow of the antenna based on the HFSS-MATLAB-API script interface and some functions that are completed in the research,then simulate several antenna structure,and choose the optimal antenna by taking antenna performance and design requirements of sweep-frequency dielectric logging antennas into consideration.Finally,the applicability of this antenna in logging environment is studied.Firstly,the HFSS script and its function structure is studied.The script function library is supplemented and improved with practical research experience.The simulation of half-wavelength dipole antenna is taken as an example to describe the flow of simulation based on HFSS-MATLAB-API script library in detail.Then,four kinds of antenna structures are simulated by HFSS software.The electrical characteristics of these antennas are analyzed.And take the engineering requirements of the sweep-frequency dielectric logging antenna into consideration,the magnetic dipole antenna is chosen as the optimal sweep-frequency dielectric logging antenna.Finally,the measured signal intensity and input voltage of the antenna are calculated.The influence of the medium environment is investigated and the conversion charts at four discrete frequencies are drawn to optimize the antenna array structure.