Tuesday, July 20, 2010

Three Forks Formation -- Basic Review, Part I

I was sent this presentation on the Three Forks formation. It's a PDF file so it might take a few minutes to download depending on your internet connection. I don't know where it was originally presented or posted. It is undated, but most likely very current since much of the information about the Three Forks Sanish has only recently been sorted out. I first received it May 24, 2010. This is the second time it's been sent to me.

The author is Stephan H. Nordeng, NDGS.

The source rock is the upper and lower Bakken shales, which includes the upper fifty feet of the Three Forks formation and probably the lower fifty feet of the Lodgepole.

Note the relationship of the Lodgepole, Bakken and Three Forks on the second slide.

The Bakken source rock has a very high total organic content (TOC) -- as much as 11%. To put that in perspective, Schlumberger says that most source rock has a TOC of at least 0.5%. "Very rich source rock might have a TOC as high as 10%" according to Schlumberger -- and, again, the Bakken has a TOC of as much as 11%.

Wikipedia lists five areas in the world where "world class" source rock exists:
  • The Bakken
  • Norwegian Sea (North) and North Sea
  • Venezuela
  • Saudi Arabia
  • Norwegian Sea (South) and The Netherlands
For comparison, TOCs:
    Slide five: note how far east and south the Three Forks Sanish in North Dakota extends; east, well beyond Minot, and south all the way to the North Dakota/South Dakota border (the TFS extends into South Dakota, west into Montana, and north into Canada).

    Slide 25 shows the various divisions of the Lodgepole, Bakken and Three Forks formations. Note that the Lodgepole has been referred to as the "false Bakken." [See this post, also, for Whiting's interest in the Scallion.]

    Slide 28: when you look at slide 28, you can see graphically where the bulk of the oil in place (OIP) will be found. The "bulls-eye" or the very center of the basin is northeastern McKenzie County and southwestern Williams County. It's interesting that the Parshall oil field is fairly east of this center but yet has been so prolific for EOG. It makes one wonder about the potential yet to be seen in Williams and McKenzie Counties.

    Slide 30: This is the slide that should knock your socks off. It shows the original amount of oil in place (OOIP) in barrels, and the estimated ultimate recovery (EUR) based on available technology. As predicted from slide 28, McKenzie County has the most OOIP, followed by Williams, and Mountrail, and then come Dunn, Divide, and Burke (6th).

    McKenzie is by the far the biggest county. Williams, Dunn, and Mountrail are about the same size. Burke and Divide are each about half the size of Williams or Dunn, so on a per acre basis, I would bet the OOIP for Burke and Divide is similar to that of the very prolific Mountrail County.

    Now in round numbers, here is the OOIP for each of these five counties (Bakken plus TFS):
    McKenzie:  36.4 billion boe
    Williams:    28.9
    Mountrail:  28.9
    Dunn:         20.1
    Divide:       17.7
    Burke:        17.0

    Again, in round numbers, here is the EUR for each of these five counties (Bakken plus TFS):
    McKenzie:   737 million boe
    Williams:     714
    Mountrail:    576
    Dunn:           475
    Divide:         200
    Burke:          375

    Finally, the EUR/OOIP ratio, as a percent:
    McKenzie: 2.0%
    Williams:   2.5%
    Mountrail:  2.0%
    Dunn:         2.4%
    Divide:       1.1%
    Burke:        2.2%

    I do not understand the low percentage for Divide County.

    But, in general, the USGS assumes that about 2% of the OOIP will ultimately be recovered. In fact, it appears that drillers are getting close to 3 or 4 percent. In some corporate presentations, the companies are suggesting they are getting as much as 8 percent (if I remember correctly; I have to confirm that). But my hunch is that the 2% figure provided by the USGS is a very, very conservative figure.

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