Bulk Well Track Import

[Lorenzo Perozzi]

Hi all,

has someone already had succes in import a bulk set of wells?. All wells are vertical, and my csv files to import is as follow:

Name, Eastin, Northing, TD (m), KB (M)

Now, when we need to define the format, we need to put either MD or TVDSS (or TVD).

 But in a case of a vertical well I only have TD(m) and KB(m). How to manage importing a bulk set of vertical well?

Many thanks in advance

[Hesham Refayee]

Hi Lorenzo,

In perfectly vertical wells, the TVD is equal to MD. In your case, define your TD column as MD.

Hope this helps.

Regards,

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Hesham Refayee

Senior Geoscientist

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[Friso Brouwer]

Lorenzo, from your question I assume you are not familiar with this kind of data, so let me write down a few things that I hope get you on the way.

TVD, TVDSS and MD are both measures of position along the well track. They differ as follows:

MD is length along the well track reference from usually regerence from the KB (Kelly Bushing) point. For vertical wells MD - TVD is constant, and is the distance between their reference levels.

TVD is the depth of the well track, usually referenced from local ground level, downward*.

TVDSS is the depth of the well track, reference from the reference plane (sea level, or it's onshore equivalent), downward*.

*Disclaimer, for the sticklers, you occasionally see that TVD is provided positive upwards...

KB, and TD are points along your well track, in fact they are the starting and ending point of the well track, so they would define the geometry of your well track completely if the well is vertical. But,

KB is typically provided as an elevation above SS (sea level == geodetic datum).

TD is typically provided as a MD.

You need to verify these are indeed the definitions used in your dataset.

In the default situation (and it is up to you to verify if you are in the default situation), you can get to a well track definition in MD by setting the KB value to 0 (zero) and that seems the most straight forward solution to your question,

If your survey is in seismic time, (not depth) then you will also need to provide depth time relations as additional step and this will actually determine how your well stick relates to the seismic data. If you plan to post well markers, import well logs, or tie seismic data the depth-time relation needs to be fairly accurate, otherwise you can just get away by providing depth-time pairs for the end points of the well track, or stick with the constant velocity option provided in the track import.

Just heads up, I did not address this, but in general you need to be extra careful and specify some extra information, if your seismic reference level is not equal to the geodetic reference plane. This is often the case in onshore surveys. 

I would recommend a good read of this help entry, especially the image towards to bottom is very clarifying in addition to the explanation here.

Friso Brouwer

Geophysical Consultant

I^3 GEO LLC

fr...@i3geo.com

+1 303 968 8688 

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[Friso Brouwer]

Oops, I see the link to the help entry I reference might not have come through or referenced to a local help file, here is the whole link to the relevant online help entry: http://doc.opendtect.org/6.6.0/doc/od_userdoc/Default.htm#survey/import/import_wells.htm?TocPath=4%2520Survey%257C4.3%2520Import%257C4.3.14%2520Import%2520Wells%257C_____0

Friso Brouwer

Geophysical Consultant

I^3 GEO LLC

fr...@i3geo.com

+1 303 968 8688 

[Friso Brouwer]

Hesham, your right, Lorenzo, I got that wrong in the TVD definition in my earlier email, TVD and MD are both referenced from KB (normally). Should have looked at that image in the OpendTect help myself first.

Friso Brouwer

Geophysical Consultant

I^3 GEO LLC

fr...@i3geo.com

+1 303 968 8688 

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[Lorenzo Perozzi]

Dear Hesham and Friso,

many thanks for your replay. 

@Hesham. By setting TVD and MD to TD in the definition format, the bulk well importation works but is missing the KB (all wells KB are set to 0). The best solution for me is to add a column to my csv file with the TVDSS depth that is MD-KB.

@Friso, many thanks for the exhaustive explanation. Effectively these terminology is alway confusing me when I'm faced with a new survey with new wells. This was the first time I tried the bulk importation and the definition format confused myself a bit. I look often to the image of your link but I think I should print and hang on my wall for reference

Thanks again for your sharing

Lorenzo

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Lorenzo Perozzi

[Hesham Refayee]

Hi Lorenzo,

You can import your wells using the "import simple wells" option wells manager . See the image below.

Regards,

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[Lorenzo Perozzi]

Many thanks Hesham for the hint

Lorenzo

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Lorenzo Perozzi