<p>I am currently working with sonic measurements in the wells and there is an observation, that velocities are faster in shales over the deviated parts of the well. So, when the relative dip between the well and bedding is high the velocity in shale is faster than in the case when the relative dip is small.</p>

<p>I have found some papers stating the same fact, but majority of them describe how to correct for that. However, I am looking for what is the reason?</p>

<p>Is it the way the measurement is done? Is it the Snell's law? Fermat's principle or anything else?</p>

CC BY-SA 4.0
2020-02-20T19:22:57.153Z
Based on the kind of articles I find, such as https://pubs.geoscienceworld.org/geophysics/article-abstract/68/2/464/302571/anisotropy-correction-for-deviated-well-sonic-logs, it seems that the reason for your findings has to do with anisotropy (loosely speaking, a direction-dependent wave speed). Are those the kind of papers you've been looking at, as well? Then the reason might be entirely physical, not related to your measurements, Snell, or Fermat...
Erik
CC BY-SA 4.0
2020-02-20T22:54:16.263Z
You would have more success searching SPE literature ( society of petroleum  engineers )
blacksmith37
<geology><rocks>
Faster shale velocities in deviated wells
akkab
# Faster shale velocities in deviated wells

(Asked by: username_0 on 2020-02-20)

I am currently working with sonic measurements in the wells and there is an observation, that velocities are faster in shales over the deviated parts of the well. So, when the relative dip between the well and bedding is high the velocity in shale is faster than in the case when the relative dip is small.

I have found some papers stating the same fact, but majority of them describe how to correct for that. However, I am looking for what is the reason?

Is it the way the measurement is done? Is it the Snell's law? Fermat's principle or anything else?

**Tags:** geology, rocks

> **Comments:**
> **username_1**: Based on the kind of articles I find, such as https://pubs.geoscienceworld.org/geophysics/article-abstract/68/2/464/302571/anisotropy-correction-for-deviated-well-sonic-logs, it seems that the reason for your findings has to do with anisotropy (loosely speaking, a direction-dependent wave speed). Are those the kind of papers you've been looking at, as well? Then the reason might be entirely physical, not related to your measurements, Snell, or Fermat...  
> **username_2**: You would have more success searching SPE literature ( society of petroleum  engineers )  

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## 0 answers

