Wednesday, November 17, 2010

Tyler Formation: Correction

For newbies: EUR is "estimated ultimate recovery." This is the estimate (in barrels of production) that a given well will produce in the well's lifetime. Some (many? most?) of the wells in North Dakota will last for decades.

Stephan Nordeng, a Department of Mineral Resources geologist, says more than 100 wells have been drilled into the Tyler formation and have produced more than 200 million barrels of oil to date.

By my calculations, that works out to a EUR of 2 million barrels/well.

What's the "party line" for the Bakken? 700,000?

SPOILER ALERT ----  SPOILER ALERT ---- SPOILER ALERT

I have been told that the "200 millions of oil to date" is incorrect and should have been 20 million bbls; see first comment below.

The 20 million figure appears correct, according to the NDIC website. But even 20 million is too high; it's closer to 17 million, so for rounding 20 is okay, but it is still significantly on the high side. One could have rounded to 15 and been closer.

There are three possibilities to explain the "200 bbls" figure: a) he misspoke (possible); b) typo by the newspaper (most likely); or, c) not sure what he is including in the "Tyler." If one includes the Heath formation which is directly below the Tyler, one can add another 65 million cumulative barrels, but 17 plust 65 is still less than 200.

However, doing that does not jive with the number of wells drilled.  There have been 87 wells drilled into Tyler and Tyler A, and 197 wells drilled into the Heath.

17 million / 87 wells = a more reasonable 200,000 bbls/well -- old wells, old technology.

By the way, the quote that more than 100 wells have produced more than 200 million barrels of oil was carried in at least two regional newspapers, the Billings Gazette and the Dickinson Press. I would assume a correction has been published but I have not seen it.

2 comments:

  1. the article was wrong ,it was 20million bbls total not 200 million.

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  2. You are correct. I should have checked the NDIC website. Three possibilities: a) he misspoke, hard to believe; b) typo by the newspaper, most likely; or, c) not sure what he is including in the "Tyler."

    The Bakken Pool includes the three formations of the Bakken and two formations of the Three Forks.

    I don't know what is included in the "Tyler." If the "Heath" formation was included, which lies just below the Tyler, then one can add 65 million bbls to the total.

    But you are correct: the Tyler and the Tyler A have produced a cumulative around 17 million combined.

    I will change the posting above. Thank you for pointing this out.

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