Performance Analysis And Optimization Design Of Dielectric Tool Antenna In Complex Formation

Dielectric logging is a method to determine the material structure in the well by measuring the dielectric constant.It can detect the oil,gas and water layers in the formation and distinguish them.There are three kinds of logging methods,among which dielectric logging is a kind of electric logging.Because the dielectric constant range of minerals and petroleum is relatively concentrated,when the reservoir water content is large,the dielectric constant measured by logging equipment will be very large,which can be used to distinguish formation structure.The main purpose of this paper is to analyze and optimize the antenna performance of dielectric tool in complex formation.This paper mainly carries out the following three aspects of work:Firstly,this paper briefly introduces the dielectric property and its polarization mechanism of rock strata.Then,according to the propagation model and propagation path of electromagnetic wave in strata,the specific expressions of the parameter changes of dielectric constant and conductivity in electromagnetic wave propagation in strata are derived from Maxwell equations.According to the simulated data parameters,the formulas of dielectric constant and conductivity are deduced backwards.Secondly,the High Frequency Structure Simulator(High Frequency Structure Simulator,HFSS)software is used to design the 1.1GHz dielectric logging cavity slot antenna unit.The structure of the antenna unit is analyzed and the initial design process of the antenna unit is recorded in detail.And the simulation analysis is carried out to obtain the initial performance positioning,so as to determine the optimization direction in the subsequent optimization process,and make the antenna unit performance achieve good in the final optimization analysis of key dimensions.Finally,based on the above optimized antenna unit,the antenna array of dielectric logging tool is designed.The array adopts the form of single sending and double receiving.The size of the antenna array is simulated and optimized,and the data performance of the optimized antenna array is tested.The designed dielectric logger antenna is placed into the simulated complex formation,and the response analysis in homogeneous,isotropic,anisotropic and heterogeneous layered media is obtained.The conclusion is that the dielectric logging tool can show the formation medium characteristics when it is in various formation modes,and the response is regular under different conditions.However,at the stratified formation boundary,the amplitude detected by the antenna will jump,and there will be mutual coupling effect between the antenna units at the receiving end,which will influence each other.However,by optimizing the structure of the single-send and double-receive antenna,After calculating the difference between amplitude attenuation and phase attenuation at two receiving antennas,it is found that the error is well reduced and the optimization effect is remarkable.