Study On The Influence Of Metal Casing On Induction Logging And Its Calibration Technology

In oil logging,induction logging is an important electrical logging method.Induction logging is usually carried out in the open hole,but in actual except for the exploration of oil and gas wells or new drilling oil and gas wells,almost all wells have to use metal casing to ensure oil well stability.When the Cased hole is studied,because of the influence of the metal casing,So that the induced electromotive force generated by the secondary electromagnetic field received on the receiving coil in the well is not only related to the stratum,but also to the metal casing.This paper studies the influence of metal casing on the induction logging and eliminates the influence of metal casing.The corrected data can be processed by mature open hole induction logging method.Therefore,it is very important to study and correct the influence of geometrical parameters and material parameters on the casing well induction logging.The main contents of the study include the following four aspects.Firstly,the basic principle of the induction logging method of the double coil is introduced,and the expression ofthe electric field component and the magnetic field component in the cylindrical coordinate system of the casing well induction logging model is deduced.Which lays a theoretical foundation for the establish of the casingwell induction logging model and the study of the response characteristics of the casing well induction logging.Second,the use of COMSOL to establish casing wells and open hole well induction logging model.Thirdly,based on the physical model,the parameters such as formation conductivity,emission current frequency,casing conductivity,casing permeability and casing thickness were changed,and different induction logging models were obtained.The distribution characteristics of electromagnetic field in open hole and casing well and the response of different formation conductivity logging were studied respectively.The influence of the emission current frequency on the electromagnetic field distribution of the casing well is studied,and the relationship between the excitation frequency and the casing parameter is determined.The influence of casing parameters such asconductivity,permeability and thickness on the distribution of electromagnetic field is studied under the condition of determining excitation frequency andstratum parameters.Finally,the study of calibration techniques.In this paper,the influence of uniform metal casing parameters on the induction logging response of cased hole is studied,which lays a foundation for the study of the influence of nonuniform metal casing parameters and the influence of metal casing parameters under inhomogeneous formation.