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在过去的十年里,已经开发了新一代的声波测井仪。这种新仪器,专门设计用来测量各种岩石的横波速度,而用常规声波仪器并不总能获得这种信息。地层横波速度资料可以改善井孔评价,尤其是增加对所关心地层力学特性的了解。声源在井液中产生纵波,常规仪器产生的纵波从声源均匀地向各个方向扩展,在地层中激发对称于井轴的波动。新式仪器的声源也在井液中产生纵波。但不对称于井轴,这种非对称纵波所形成沿井壁传播的声波,与常规声源激发的声波沿井壁传播有很大差异,新式声源产生的波型的特性可以用来测量地层横波速度。常规声波测井的声源是单极子换能器,可以数值模拟成点声源。已成功地用于测井仪的新式声源包括偶极子和四极子,这些声源的数值模拟,需要比单极子仪器更为复杂的声源表达式。作为一种类型,新式声波换能器被称为多极子。
In the past decade, a new generation of sonic logging tools has been developed. This new instrument, specifically designed to measure the shear velocity of various rocks, is not always available with conventional sonic instruments. Stratigraphic S-wave velocity data can improve wellbore evaluation, especially to increase understanding of the mechanical properties of the formation of interest. The sound source generates longitudinal waves in the well fluid. The longitudinal waves generated by the conventional instruments expand uniformly in all directions from the sound source to excite the fluctuations in the formation symmetrically to the shaft axis. The sound source of new instruments also produces longitudinal waves in the well fluid. But asymmetrical to the shaft axis. The acoustic waves propagating along the borehole wall formed by such asymmetric longitudinal waves are quite different from the acoustic waves excited by conventional acoustic sources along the borehole wall. The characteristics of the wave patterns generated by the new acoustic sources can be used to measure Stratigraphic shear wave velocity. Conventional acoustic logging sound source is a monopole transducer that can be numerically simulated as a point source. New sources of sound sources that have been successfully used in logging tools include dipoles and quadrupoles. The numerical simulation of these sources requires more complex source expressions than monopole instruments. As a type, new acoustic transducers are called multipoles.