Simulation Of Acoustic And Mechnial Proerties Of Sound Insulation In Logging While Drilling

Known as the "blood of industry",petroleum has an important impact on a country's economy,national defense and society.How to improve the extraction efficiency of oil is an urgent problem to be solved.In recent decades,LWD has become a new exploration method,but the collar wave generated in the exploration process will affect the extraction of formation signals.How to extract formation signals more effectively has become a key topic for many engineers and scientistsBased on the research background of LWD,through the analysis of the acoustic characteristics of different groove structures,the acoustic isolates with better acoustic performance are designed,which are called low porosity acoustic isolates.In this paper,first of all,based on the related theory,periodic structures by using the finite element software to calculate the band structure of different groove structure.It is found that all calculation of band appear inverted u-shaped groove structure,did not form a complete band gap,the further calculation groove in the water of the band gap structure,it is found that low porosity groove structure band structure has little change.From the perspective of band structure,no matter the traditional groove structure,the layered grid groove structure and the low porosity groove structure,they cannot produce better band gap.Then,by using the method of frequency response function curve,the same excitation point and receiving point are set on different groove structures.Comparison.By compared different structure,the frequency response characteristics are obtained.The effects of groove width and depth on the group velocity of elastic wave are studied in an idealized groove model.Then the responses of different groove structures in the formation and fluid are researched.Firstly,the full wave responses of finite element software and analytical method are calculated when the sound source frequency is 4 k Hz.By comparing the calculation results,it is found that they are basically the same,which verifies the correctness of the finite element software calculation.Then the displacement full wave response and STC signal processing of smooth drill collar in fast and slow formation are calculated,which are consistent with the previous comparison.In order to analysis the waveform characteristics of the different groove,we calculate the frequency of the sound source is 8k HZ full wave of displacement in different groove structure.All of the structure of the transformation of stoneley wave amplitude value almost always increase,this is because the original spread along the wall of collar wave to the groove part of the energy leakage will lead to delay into a transformation of stoneley wave.Further we analyze the ability of different structures to extract formation signals and calculate the displacement full waves of different groove structures when the sound source frequency is 14 k Hz.STC method is used for extracting the strata information.It is found that the groove structure with low porosity can better extract the refraction p-wave and s-wave from the formation.Finally,the mechanical properties of different slot structures are calculated.The natural frequencies of different drill collar structures differ greatly from the excitation frequencies of sound sources,so resonance phenomenon will not occur.The results show that the maximum stress of the sound insulation with layered structure is the highest compared with other structures.By keeping other conditions unchanged,the maximum stress changes of different groove depths and different groove widths are calculated,and it is found that the maximum stress increases gradually with the deepening of groove depth in other structures except the inner groove structure.With the increase of groove width,the variation of maximum stress is not the same.In addition to the internal groove structure,the maximum stress of the structure is the smallest when the groove width is the widest.