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在科罗拉多州的 Limon 附近进行了各种衰减测量。这里从不到100英尺到大约4000英尺的深度范围内,皮尔(Pierre)页岩异常地整合。在远至750英尺的距离内,对爆炸震源和机械震源激发的质点速度波形进行了测量。爆炸震源激发出比较清晰的胀缩脉冲,沿垂直或水平传播路径可以观测到。重锤下投到钻井的底部,激发出带有垂直质点运动的水平传播剪切波。在每种情况下,三分量检波器组紧紧箝固在钻井里,接收到的信号用一个能校准的宽带系统进行放大,并进行示波和记录。每个波形的频率通过傅里叶分析得到,并且,作为频率的函数,衰减就是利用这些频谱计算的。在50到450周/秒的频带内,对垂直传播的胀缩波进行的6次测量给出平均值α=0.12f。对于频带20—125周/秒内水平传播垂直运动的剪切波,结果为α=1.0f。每种情况的衰减用每传播1,000英尺的分贝数表示,f 是以周/秒为单位的频率。这些测量说明了,皮尔页岩的性质与粘滞弹性介质不同。
Various attenuation measurements were made near Limon, Colorado. Here less than 100 feet to about 4,000 feet depths, the Pierre shale anomalously integrated. Within a distance of up to 750 feet, the particle velocity waveforms excited by the explosion source and mechanical source were measured. The explosion source excites a relatively clear expansion and contraction pulse, which can be observed along the vertical or horizontal propagation path. Hammers dropped to the bottom of the well to excite horizontal propagating shear waves with vertical mass motion. In each case, the three-component geophone is tightly clamped in the well and the received signal is amplified with a calibrated wide-band system for oscillography and recording. The frequency of each waveform is obtained by Fourier analysis, and as a function of frequency, attenuation is calculated using these spectra. Six measurements of vertically propagating swell waves in the frequency band of 50 to 450 cycles / second gave an average of α = 0.12f. For horizontal shear wave propagating vertically in the frequency band of 20-125 weeks / sec, the result is α = 1.0f. The attenuation in each case is expressed in decibels per thousand feet of propagation and f is the frequency in weeks / seconds. These measurements show that the nature of the pen shale is different from that of the viscoelastic medium.