The Study On Signal Processing Of Array Induction Logging With Three Frequencies

With the continuous development of oil exploration technology,logging equipment is also constantly upgrading.Array induction logging tool is one of the most effective resistivity logging tool.It can provide a wealth of formation information and plays an important role in the accurate evaluation of oil and gas reservoir.In this paper,we study the signal processing method of an array induction logging with three frequencies.It includes the skin effect correction of three frequencies logging signal,filter design of signal focusing synthesis and resolution matching filter design of different depth of investigation curves.The research results lay the theoretical foundation for the development and design of three frequencies array induction logging tool.The research contents include the following five aspects.In the first part,the basic principle of array induction logging is analyzed,and the structural parameters of the tool are given.Secondly from the three coils system brings the induced electromotive force,the apparent conductivity,skin effect and other basic theoretical knowledge.Finally,the 1D,2D characteristics and uniform layer response characteristics of the three frequencies array induction logging tool are studied in detail from the geometric factors of Gianzero.From three aspects,including different arrays,different working frequencies and different conductivities,discuss the tool vertical resolution and radial investigation depth.In the second part,we study the skin effect correction method of three frequencies array induction logging signal.Firstly,the current methods of skin effect correction are discussed and the advantages and disadvantages of these methods are analyzed.An new skin correction method of the three frequencies array induction logging tool is proposed from the relationship between frequency and apparent conductivity.The theoretical basis and the realization principle of the three frequencies skin effect correction method are studied.Finally,we compare the difference between the curve after skin effect correction and the skinless effect of the two different three layers model.It verifies the practicability of the three frequencies skin effect correction method.The third part studies the filter design problem of three frequencies logging signal focusing synthesis.Firstly,the design principle of the focusing filter,the selection of the objective function,the application of the correlation function as well as the problems and solutions in the process of designing the filter are studied.Secondly,soft constraints are analyzed,such as constraint conditions on the filter method.Finally,true resolution focusing synthesis filters with 15 background conductivities and 7 different depth of investigations are designed.The fourth part tests and improves the focus synthesis filters through processing the specific model signal.First of all,use the designed focus synthesis filter to process the forward modeling data about 15 background conductivities.The logging curves with different depth of investigation and different vertical resolution were synthesized.From the synthetic results,we can judge whether the filter design is reasonable.Adjust the filter constraint parameter to improve the designed filter.Secondly,seven different detection depths and different resolution curves are matched to each other,and the logging curves with the same resolution are obtained.The fifth part is the computer simulation.Firstly,the algorithm design of the whole signal processing is given.Secondly,the 21 layers model with contrast ratio of 10 and 100 as well as the model of the Oklahoma model are simulated.The adaptabilities of the research algorithm and the design filter are verified.