| Acoustic logging is in the field of geophysical and rapid development of a wide range of logging methods, acoustic logging on the recent formation of the detailed description of wells is not a substitute for other methods of logging. The acoustic radiation research and the interaction with the borehole are understanding and explanation cross hole seismic data of actual measurement of the essential foundation. With the actual production of the basic involved are well casing, International log markets logging in cased hole logging of the total workload of 47%. So it carried out the study of the plane SV wave incident axis tilt wells coupled with the well casing is more practical significance. Demands that we must study well casing of the sound field, the paper is in this premise of the research.This paper introduces the history of the acoustic logging and development, and then introduced the status of seismic exploration wells, and then introduced the study of scattering of history and current situation, discussed the study on the significance of coupling in well casing, and according to actual production, the establishment of the corresponding casing wells Physical model: the inner layer for the fluid , the second layer of steel casing, the third layer for the cement layer, the outermost layer of Biot Solid. Fluid exists only P waves, Steel casing and cement layer may have P-wave,SV wave and SH wave, Biot Solid may have the first and second category of scattering P wave,SH-wave and incident and scattering of SV waves. Convenient for the study, the establishment of cylindrical coordinates, the Z-axis coincide with the well axis, according to general principles of Fourier series, the incident plane started for the SV-wave band-bessel function of the stack, the use of cylindrical coordinates the solution of wave equation , the displacement,stress,strain expressions and wide frequency of Biot theory, detailed derivation of the expression of wells inside and outside sound field,When the wells outside the Biot solid for fluid-saturated strata, the plane SV wave incident axis tilt wells coupled with the well casing。Again based on the three boundary conditions on the interface can be the sound field in the potential function defined coefficients. Thus be expressed of wells inside and outside sound field with potential function.Production as a result of real life, our measurements are carried out in the wells, Therefore, use of Matlab software on the wells outside the Biot solid for fluid-saturated strata, the plane SV wave incident axis tilt wells coupled with the well casing by a numerical simulation.The paper first discussed when the plane SV wave incident Well axis tilt, the incident angle of the impact sound pressure wells. In the hard strata formation, in the angle of incidence greater than 0 degrees, 90 degrees less than the framework of well-axis sound pressure near the fluid in the middle-and high-frequency band, a series of sharp resonance peaks,with the incident angle increases, the resonance peaks move to low-frequency,these results, the situation is similar with the open hole; when the incident angle of 57 degrees, the most significant resonance phenomenon, the maximum sound pressure wells; In the incident angle of 45 degrees or so, in the frequency range of 40KHz-50KHz more than a formant,these results, the situation is similar with the P wave. In the soft strata formation, when the angle of incidence is less than 50 degrees, the well-axis sound pressure value of fluid near the small,these results, the situation is similar with the open hole ,need to be larger when the incident angle, the resonance phenomenon is obvious; As the angle increases, the frequency f is greater than in the high frequency area 20kHZ a series of sharp resonance peaks,and with the increasing incidence angle, the resonance frequency to the low-frequency mobile, soft stratum than the rate of the mobile hard formation. While the incident angle of 67 degrees, the most significant resonance phenomenon, maximum sound pressure wells.As porosity and permeability of the oil and gas resources in the development of important significance, the paper mainly inspected the porosity and permeability of the impact of sound pressure wells. Porosity of the inspection results show that: Whether hard or soft strata formation, taking into account the porosity changes arising from the permeability and bending of the changes, porosity clear influence on the sound pressure wells, In the soft strata formation, small-angle incidence, the formant disappear, the resonance phenomenon was not obvious, When the frequency is lower than 20KHZ, the influence of small pressure;with the porosity increases, the resonance peaks move to low-frequency,these results, the situation is similar with the open hole.In the hard strata formation, with the porosity increases, the resonance peaks move to low-frequency,When the smaller the angle of incidence, the higher the frequency, the wells of the resonance frequency of sound pressure to the low-frequency movement of the more obvious, with the changes in the porosity range of formant change more fierce;with the porosity increases, the resonance peaks move to low-frequency,these results, the situation is similar with the open hole。For Biot solid, permeability is a very important parameter, so we focus on the case study in well casing from permeability induced changes of sound pressure wells. The results show that: both hard and soft strata, permeability only affect sound pressure peak, and the location of the resonance peak was less affected. These results, the situation is obviously different with the open hole.Since the actual measurement, when logging equipment are generally placed in the wells, under normal circumstances require wells in the shaft, but due to various errors, apparatus is not well in the shaft, and with advances in technology, machines can be placed on the wall, so we need to study deviated from the well-axis measuring the impact of research results show that: In both hard and soft strata, the different position of the wall Sound pressure differences more obvious,。the hard formation, when measured less than 2KHz frequency, different position on the wall of sound pressure is basically the same,Not much difference in 3KHz。but,when more often than 4KHz, the different position of the wall Sound pressure differences more obvious;the soft strata, To a larger incidence angle,when measured less than 1KHz frequency, different position on the wall of sound pressure is basically the same, when more often than 1KHz, the different position of the wall Sound pressure differences more obvious, so both hard and soft strata, different from the position of sound pressure differences must be considered. This article is the work of our predecessors is mainly directed against the background well casing of the sound field carried out, the use of wide frequency of Biot theory, detailed derivation of the expression of wells inside and outside sound field,When the wells outside the Biot solid for fluid-saturated strata, the plane SV wave incident axis tilt wells coupled with the well casing,finally, Matlab software was simulated, been a number of new results and understanding.In this paper, the research done so far no one has done, has some innovative. This article has been received by some of the findings and knowledge, to cementing quality testing,,repairing old wells,explaining the seismic section of the vertical wells and seismic survey data have a certain significance.
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