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New, rigorous assessment of shale gas reserves

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New, rigorous assessment of shale gas reserves

Unread postby Graeme » Fri 01 Mar 2013, 10:09:11

New, rigorous assessment of shale gas reserves forecasts reliable supply from Barnett Shale through

The study, conducted by the Bureau of Economic Geology (BEG) at The University of Texas at Austin and funded by the Alfred P. Sloan Foundation, integrates engineering, geology and economics in a numerical model that allows for scenario testing based on many input parameters. In the base case, the study forecasts a cumulative 44 trillion cubic feet (TCF) of recoverable reserves from the Barnett, with annual production declining in a predictable curve from the current peak of 2 TCF per year to about 900 billion cubic feet (BCF) per year by 2030.


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Re: New, rigorous assessment of shale gas reserves

Unread postby Keith_McClary » Sat 02 Mar 2013, 02:47:48

While the BEG model shows the correlation between price and production, it suggests that price sensitivity is not overly dramatic, at least in the early phase of a formation's development. This is because there are still many locations to drill in the better rock, explains Tinker, which is cost effective even at lower prices.
"Drilling in the better rock won't last forever," says Tinker, "but there are still a few more years of development remaining in the better rock quality areas."

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Re: New, rigorous assessment of shale gas reserves

Unread postby kuidaskassikaeb » Fri 08 Mar 2013, 18:06:58

When I was reading the FAQs I saw this

Decline rate is the function of permeability, porosity and well depth and is proportional to 1/sqrt(Time) that is the square root of time.
Decline rate is the function of permeability, porosity and well depth and is proportional to 1/sqrt(Time).
that is the square root of time.

This is something that bothers me. I notice that typically the declines are plotted on log scale and people are always talking about decline rates in exponential. Anyway I looked around and it seems that while the Bermans are talking about high decline rates the operators are expecting very slow long term declines, and the square root of time dependence used in this study is by far the most optimistic I have seen, and most shale operators are already assuming decline rates better than the theoretical best.

Bermans take on the Bakken shows the effect of assuming the decline rate on the ultimate recovery.
http://theseventhfold.files.wordpress.c ... r_2009.pdf

Since the takeaway on this paper seems to be that the Barnett will last forever, and the data in his paper is from the Barnett somebody got it wrong.
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Re: New, rigorous assessment of shale gas reserves

Unread postby SamInNebraska » Fri 08 Mar 2013, 19:14:30

Just as a practical aside, it strikes me that "new" and "rigorous" aren't the right words when talking about a particular producing formation which has been...producing...for 31 years. Call it a "gee we've manufactured wells all over this area and if we extrapolate the dregs that are left" its more like guessing at how much cereal is left in the box after you've eaten 3/4's of it...hell a chimpanzee could do that. Getting the answer right from the beginning, now THAT requires some talent. Like what Hubbert did.
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Re: New, rigorous assessment of shale gas reserves

Unread postby Buddy_J » Fri 08 Mar 2013, 19:44:55

kuidaskassikaeb wrote:Bermans take on the Bakken shows the effect of assuming the decline rate on the ultimate recovery.
http://theseventhfold.files.wordpress.c ... r_2009.pdf

Since the takeaway on this paper seems to be that the Barnett will last forever, and the data in his paper is from the Barnett somebody got it wrong.


It is somewhat amazing how many low EROEI, uneconomic wells have been drilled since Berman wrote that, and the BEG says will continue to be drilled in the face of such poor results, for the following decades. It would be nice if reality would just conform to expectations sometimes.
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Re: New, rigorous assessment of shale gas reserves

Unread postby dissident » Sat 09 Mar 2013, 01:55:33

Image

I don't see t^(-0.5) dependence in this graph from the same report that claims algebraic time dependence. All I see is exponential dependence. It's easy to tell by the fact that the tails for production initiated before 2010 are basically hitting the time axis over the range shown. With t^(-0.5) dependence all the tails would be extending past 2030.

Here is what t^(-0.5) dependence looks like:

Image

(from this link)
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Re: New, rigorous assessment of shale gas reserves

Unread postby kuidaskassikaeb » Sun 10 Mar 2013, 17:31:46

Mr. Dissident person:

Um I got the square root dependence out of the FAQs for the papers, which as far as I know are not available. Your graph is accurate, but exponentials actually look like the graph you gave also. You would have to put them next to each other to see the difference. In the long term one square root of T dependence is equivant to a B of 2. This according to Berman is outside the range of theory and must be wrong. But it is what you expect from diffusion and other processes where flow rate is propotional to pressure difference and removing the gas produces a depleted layer. To me this one half power thing was a big insight, in that despite reading the posts regularly on this site, I never quite figured where people disagreed.

I thought that Fraking was supposed to be a short term thing with a fast payback, that kind of died off quickly, but produced lots of gas. Now I find out that it is supposed to be a long term thing with a slow payback due to a long production tail. Also if these people are using a square root of T and the data has been exponential for another 4 years. Well that's not right.
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