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Vol. 20, July 2009 |
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Tobin Newsletter - Vol. 20, July 2009
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Don't Let Haynesville Prospects "Disappear"
How to Minimize the Risk By Knowing “the True (Well) Path”
Click here to download this newsletter as a PDF.
There are multiple risk elements involved in oil & gas prospect generation in any area. It’s logical to assume any company wants to keep risk at a minimum. But what most companies don’t know about the wellpaths in their prospect areas CAN hurt their chances of finding gas or oil.
The picture to the right demonstrates some of the superb wellpath control that is currently being captured by P2 Energy Solutions in the Haynesville Shale Play area.
Why should you care about this directional well survey data?
It is crucial information for any company prospecting for oil or gas, and here's why:
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(click to enlarge)
1) What you don’t see (wells/wellpaths) may hurt your interpretation.
In a previous newsletter entitled “How do you know if your well data is real or an illusion?” (Vol, 15, Feb. 2009) the issue of missing wells and wellbores was discussed. See also our instructional handout, "What's missing on your maps?" In almost all areas, because of historic industry collection practices, 15-20% of the drilled wellbores are missing. The missing wellbore issue causes a related pitfall for interpreters: They could be using the wrong well data.
2) Well data will get linked to the wrong well header.
The simplest and most common example of where wellbores are missing from the industry well records is shown in Figure 1. The sidetrack is there that led to a discovery, but the original hole is missing.
Figure 1.
What then happens to all the digital well data (logs, tops, perfs, cores, paleo, etc.) in the original hole (OH)? In the digital interpretation environment, all the data from the original hole is either lost (rejected) or it is linked incorrectly (lumped) with the sidetrack (ST) wellbore. Spatially the OH & ST are often quite different, and the ‘lumped’ OH data linked to the ST creates confusing subsurface ‘control’ points.
In areas with horizontal drilling like the Haynesville or Barnett Shale plays, the ‘pilot’ hole often becomes this ‘missed’ wellbore. All this incorrect information plays havoc with correct interpretation.
3) Formation tops being linked to the wrong wellbore.
As we review formation ‘tops’ (depths in a well of a specific pay horizon or lithologic unit) reported in state agency final well forms or in industry vendor databases, it is frequently not clear what wellbore the tops came from: the pilot hole or the sidetrack. Formation tops are often picked in the pilot hole because they have less distortion due to directional drilling and clearer log response than in horizontal logs.
But more often than not, formation tops are really associated with the ‘officially numbered’ wellbore - the horizontal wellbore. Thus great care must be exercised using reported tops in interpretation efforts.
Secondly, in tops created in-house by company interpreters, similar care must be exercised to link these tops to the correct directional survey, wellpath and respective API number. The Shelby County example (Figure 2), where 7 wellbores exist and originate from the same surface location, is an example that linking tops to the correct wellpath is not always trivial.
Figure 2.
Even when all wellbores for a well are recognized, log headers and other forms of well data require care to link as sometimes there is no sidetrack indicator, or sometimes the wrong sidetrack number is indicated. Further there are differences in sidetrack numbering based on information available or provided to service companies at the time. The long and short of it is that information from the same wellbore may get referenced as if it is from different wellbores - only care in comparing services dates and depths will eliminate data integration errors.
The Good News
Missing data on your maps means an unclear picture of what’s going on underneath the surface. No one can afford to drill unnecessary wells in this competitive environment.
The good news: P2 Energy Solutions is now targeting the Haynesville-Bossier-Cotton Valley play area of NW Louisiana and NE Texas to create a directional survey composite database that focuses on solving several of the common risk factors:
1) Every wellbore is recognized and assigned an API number,
2) Every wellbore ( where data is available) has an accurate directional survey composite captured and created.
3) Each directional survey composite is standardized for mapping purposes and formatted for use in the common industry interpretation applications.
For the interpreter, there is not finer wellpath control available anywhere.
If you’re interested in Haynesville-Cotton Valley-Bossier directional well survey data, head to http://info.p2es.com/tobinhaynesvilleDWS and we’ll keep you up-to-date on the progress. For further questions about P2 Energy Solutions’ aggressive work to add missing wellbores to well inventories, contact us at http://info.p2es.com/tobin. |