<p>Good afternoon. Inside the creation of the synthetic seismogram some softwares have the option to run what is called "sonic calibration" or "checkshot calibration". I have some questions:</p>

<p>1)why some softwares consider that the sonic should be calibrated while others consider the checkshot should be calibrated?</p>

<p>2)what is the interpretation of a positive drift curve and a negative drift curve?</p>

<p>3)According to my research, in order to apply drift correction, you should apply a smoothing to the drift curve. In the case of the softwares that apply checkshot calibration, the idea is to use the sonic data points to infill the checkshot. Also you have 3 curves in one log track:the original sonic log, the original checkshot and the calibrated checkshot. You then have another track with two drift curves: a fixed one, that represent the difference, in time value,between the original  checkshot and the original sonic log a a movable drift curve. In this curve,if apply a lot of smoothing, the corrected checkshot curve will be more similar to the original sonic curve. If you apply a small smoothing, the calibrated checkshot curve will be more similar to the original checkshot curve.</p>

<p>Is the idea that the calibrated curve to make it more similar to the original sonic curve, the original checkshot curve or something in between?why?</p>

<p>4)Similar to question 3, how does this apply in case you do a sonic calibration?</p>

<p>5)Are there big consequences of not doing checkshot/sonic calibration?which ones?</p>

CC BY-SA 4.0
2021-06-15T10:09:24.037Z
You can find your answer in this paper: Seismic versus sonic velocities: A vertical seismic profiling study
Boon Ee Juan
CC BY-SA 4.0
2021-06-15T18:23:13.493Z
@BoonEeJuan *If* it is the paper you refer to, it would be easier for the OP to retrieve it with a link [like this one](https://www.researchgate.net/publication/274443386_Seismic_versus_sonic_velocities_A_vertical_seismic_profiling_study) which leads e.g., to [doi 10.1190/1.1441745](http://dx.doi.org/10.1190/1.1441745).
Buttonwood
CC BY-SA 4.0
2021-06-30T15:37:01.070Z
This is the paper GEOPHYSICS Volume 49, Issue 8
Seismic versus sonic velocities: A vertical seismic profiling study
Authors: Robert R. Stewart, Phil D. Huddleston and Tze Kong Kan
https://doi.org/10.1190/1.1441745
Steve
<geophysics>
Construction of a drift curve in the well tie calibration and how to interpret it?. Sonic calibration vs checkshot calibration
reed_adkins86
# Construction of a drift curve in the well tie calibration and how to interpret it?. Sonic calibration vs checkshot calibration

(Asked by: username_0 on 2020-05-18)

Good afternoon. Inside the creation of the synthetic seismogram some softwares have the option to run what is called "sonic calibration" or "checkshot calibration". I have some questions:

1)why some softwares consider that the sonic should be calibrated while others consider the checkshot should be calibrated?

2)what is the interpretation of a positive drift curve and a negative drift curve?

3)According to my research, in order to apply drift correction, you should apply a smoothing to the drift curve. In the case of the softwares that apply checkshot calibration, the idea is to use the sonic data points to infill the checkshot. Also you have 3 curves in one log track:the original sonic log, the original checkshot and the calibrated checkshot. You then have another track with two drift curves: a fixed one, that represent the difference, in time value,between the original checkshot and the original sonic log a a movable drift curve. In this curve,if apply a lot of smoothing, the corrected checkshot curve will be more similar to the original sonic curve. If you apply a small smoothing, the calibrated checkshot curve will be more similar to the original checkshot curve.

Is the idea that the calibrated curve to make it more similar to the original sonic curve, the original checkshot curve or something in between?why?

4)Similar to question 3, how does this apply in case you do a sonic calibration?

5)Are there big consequences of not doing checkshot/sonic calibration?which ones?

**Tags:** geophysics

> **Comments:**
> **username_1**: You can find your answer in this paper: Seismic versus sonic velocities: A vertical seismic profiling study  
> **username_2**: @username_1 *If* it is the paper you refer to, it would be easier for the OP to retrieve it with a link [like this one](https://www.researchgate.net/publication/274443386_Seismic_versus_sonic_velocities_A_vertical_seismic_profiling_study) which leads e.g., to [doi 10.1190/1.1441745](http://dx.doi.org/10.1190/1.1441745).  
> **username_3**: This is the paper GEOPHYSICS Volume 49, Issue 8 Seismic versus sonic velocities: A vertical seismic profiling study Authors: Robert R. Stewart, Phil D. Huddleston and Tze Kong Kan https://doi.org/10.1190/1.1441745  

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