摘要
本文介绍了周围为无限固体介质的裸眼井中多极子声源激发的弯曲波、扭转波等模式声波的理论基础,从数值上计算了弯曲波等模式在不同的井孔半径下,硬、软地层井孔中的速度频散曲线。结果表明,在截止频率处,其速度最大且等于地层的横波速度.计算了理想的井孔模型(无衰减)及有吸收衰减情况下由偶极子及四极子声源激发的声波波形图,从图形看出其首波是以横波速度传播的。曾在模型井中进行了测试,实验结果与理论计算有较好的一致性。本文所介绍的方法对于软地层中横波速度的测量有重要意义,有助于进一步研制横波测井仪。
Fundamentals of torsional, flexural and the other modes excited by multipole soprce in afluld—filled borehole surrounded by infinite elastic formation are introduced in thispaper. Dispersion curves are calculated respectively for various borehole diameters in bothfast and slow formations. The numerical results show that the velocity at cut-off frequency isthe maximum and is equal to the shear wave velocity of the solide formation. Calculating thesynthetic waveforms excited by dipole and quadrupole sources in a fluid-filled borehole withor without physical attenuation, we find out that its head wave velocity is the shear wave ve-locity. Experiments have been made in test well, the results agree with the theory. Thc meth-ods introduced in this paper are very important to shear wave velocity logging in slow, forma-tion and will be helpful to the development of direct shear wave logging tool.
