[OpendTect_Users] Importing data sets with different survey geometries

[Paul de Groot]

Hello Nayyer,

Good question. I am glad you asked this because this is one of these hidden
features in OpendTect that no one seems to know about. Here is the work
flow and a few other tips you may find useful. (For your info: A), B) and
C) are open source features; for D) you need commercial plugins.)

*A) Merging of 3D surveys with different geometries.*

   1. Load Volume A in Survey 1 (survey parameters are correct for A)
   2. Load Volume B in Survey 2 (survey parameters are correct for B; the
   file is now stored in OpendTect's own CBVS format)
   3. Open the Menu: Import -> Seismics -> CBVS -> From other Survey. You
   can chose between taking the nearest trace at the new inline, crossline
   positions and interpolating neighboring traces to obtain interpolated
   traces at the new inline, crossline positions.

*B) Shifting one volume 8ms*

   1. You could have shifted either Volume A or Volume B during the SEGY
   data load. Chose "Mostly Rev. 1" and the wizard will show a window where
   you can overrule a couple of parameters including the SEGY start time in ms.
   2. Or, you create and apply the "Reference shift" attribute after
   loading.

*C) Aligning time-lapse (or other) volumes*

   1. Create and Apply the Match Delta attribute. This attribute computes
   local cross-correlations to determine how much each position in a Cube
   should be shifted to align with a reference cube.
   2. Create and Apply a smoothing filter to filter the Match Delta Cube.
   You can do this with the Volume Statistics Attribute (output Average, or
   Median).
   3. Create and Apply the Delta Resample Attribute using the smoothed
   Match Delta Cube to align Cube A. (I recommend evaluating the parameters of
   the smoothing operator on a test line before applying it to the entire
   volume.)

*D) Smoothing Time-lapse differences and Time-lapse Inversion*

   1. If you have access to Common Contour Binning plugin you can create
   and apply a Localized CCB smoothing operator to enhance differences in
   response due to saturation differences.
   2. If you have SynthRock you can stochastically simulate thousands of
   difference models and match these against the (optionally CCB smoothed)
   difference cube in a HitCube inversion work flow, see e.g.
   http://dgbes.com/images/stories/PDF/wo0513_huck.pdf .

I hope this helps. Good luck with your project and best regards,

Paul.


-- 






*Paul de GrootPresident dGB Earth Sciences, Nijverheidstraat 11-2, 7511 JM
Enschede, The Netherlands.Tel. +31 53 43 15 155, Fax +31 53 43 15
104.paul.degroot at dgbes.com <paul.degroot at dgbes.com>, www.dgbes.com
<http://www.dgbes.com/>, www.opendtect.org <http://www.opendtect.org/>.*



On Thu, Dec 26, 2013 at 7:10 PM, Nayyer Islam <nislam at mtu.edu> wrote:

> Hi All,
> I am working on some time-lapse data that were restricted to a small area
> aiming to study the one producing reservoir. I have legacy data from the
> same area but with a broader survey geometry and different inline and xline
> numbers. One main difference between the two geometries is that the
> time-lapse data starts from -8ms while legacy starts from 0ms.
>
> I am having trouble in loading both the data-set under the same
> survey/project.
>
> Any suggestions on how can I import the both data-sets under one survey???
>
>
> Sincerely,
> *Nayyer Islam*
>
> PhD Candidate, Geological Engineering
> President, Geophysical Society at MTU
>
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