CALCULATING THE TRUE SEISMIC VELOCITY OF THE DIPPING INTERFACES USING A NEW GENERALIZED ALGORITHM | ||
| Journal of Egyptian Geophysical Society | ||
| Volume 15, Issue 1, 2017, Pages 165-173 PDF (10.58 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jegs.2017.385709 | ||
| Author | ||
| M. Rabei | ||
| * Exploration Division, Nuclear Material Authority, Cairo, Egypt. | ||
| Abstract | ||
| The shallow refraction seismic technique is broadly used to determine the elastic moduli and true depths of the underlying layers by calculating the true velocities of seismic waves travelling through these strata, which are critical to engineering investigations. At dipping interfaces, computing the true seismic velocity is so difficult until the harmonic mean velocity approximation of the apparent velocities is used to figure out the true velocity. However, the harmonic approximation fails to determine the true velocity of the dipping interfaces when the dipping angles of the interfaces are equal or greater than the critical angles. This study presents a new generalized algorithm to compute the harmonic mean velocity of any dipping interface using a new formula aiming at providing us with a good estimation for the true velocity of these inclined interfaces. This does not only maintain the error percentage between the calculated harmonic mean velocity and the true velocity, but it also succeeds in determining the harmonic mean velocity even when the dipping angles of the dipping interfaces are equal or greater than the critical angles. The trials experienced on the provided synthetic and real seismic data, representing most realistic earth models, establish that the harmonic velocities estimated using the generalized algorithm to fit the actual model velocities with a fair measure of error percentage, can be remained below 0.7% within synthetic data and 1.5% within real case studies. | ||
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