<DrumBeat: January 27, 2008The Oil DrumCSIRO Future Fuels Forum>

64 comments on US Petroleum Supply, Ethanol, and State of the Industry - API

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mdsolar on January 26, 2008 - 4:30pm Permalink | Subthread | Parent | Comments top

I think that is correct. I'm just not sure if this should be called a shale play since the drilling is not in shale but in dolomite and sandstone. I think this is why people are so uncertain about how to make a guess about the recoverable fraction. Estimates range between 50% and 3%.

Chris

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westexas on January 26, 2008 - 4:54pm Permalink | Subthread | Parent | Comments top

The key point is that the Middle Member--the shaly dolomite/limestone/sandstone--is productive locally, presumably in discrete traps. The billions and billions of oil estimates principally come from extrapolating the shale thickness across the whole basin. Again, the two key questions are to what extent the shale members are commercially productive across a large region and what the recovery factor is going to be.

http://www.contres.com/index.cfm?id=50

The Bakken formation is widespread and relatively uniform in development throughout the Montana and North Dakota portions of the Williston Basin. The Bakken formation consists of three lithologic members—the upper shale, middle member and locally a lower shale. The shales are highly organic, thermally mature and overpressured and act as both a source and reservoir for the oil. The middle member is also productive locally and varies in composition from a silty dolomite, to shalely limestone or sand across the Williston Basin. Horizontal drilling and advanced fracture stimulation technologies have enabled commercial recovery from this historically non-commercial reservoir. Generally, the Bakken formation is drilled horizontally on 1,280-acre units to vertical depths ranging from 9,000 to 10,500 feet with opposing horizontal laterals each extending approximately 4,500 feet, for a total drilled footage of approximately 18,000 to 21,000 feet. The wells are typically fracture stimulated to maximize recovery and economic returns.

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mdsolar on January 26, 2008 - 5:40pm Permalink | Subthread | Parent | Comments top

The description, as I understand it, is that it is continuous so the oil does not pool up anywhere, it just fills the middle member. I think that the geology has been mapped so that it is more interpolation than extrapolation. Perhaps we won't know how much can be recovered until it is all recovered. The USGS is unwilling to publish the study it had done though you can read in on the web: http://www.undeerc.org/Price/

Chris

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westexas on January 26, 2008 - 5:48pm Permalink | Subthread | Parent | Comments top

Okay, let me try one more time. From the excerpt above:

The shales are highly organic, thermally mature and overpressured and act as both a source and reservoir for the oil.

The middle member is not continuously productive across a widespread area--that is what locally productive means.

The shale members are continuously productive across a wide area.

The key question is whether the shales are commercially productive across a widespread area.

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Gail the Actuary on January 26, 2008 - 6:02pm Permalink | Subthread | Parent | Comments top

I think the Bakken formation would be an interesting topic for a TOD post or a guest post.

On the natural gas side, unconventional production has done very well, and has prevented a steep decline in natural gas production. We can't expect as much on oil, but every little bit helps.

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mdsolar on January 26, 2008 - 9:14pm Permalink | Subthread | Parent | Comments top

I think I see where we are missing each other. My meaning is that it is spatially continuous. There are no places that it drains to, it is just one wide layer or trap. Your meaning is that the oil is located where it formed (or nearly so). My picture is probably too simplistic, as some areas will have more oil than others and those will be the commercial portions. This model is a little above my head but it might help you get a feel for what people are thinking: http://www.searchanddiscovery.net/documents/2006/06035flannery/index.htm
Again, what is interesting to me is that there seems to be something to be remarked on in the aggregate production numbers from the conference call. Perhaps this is a slow motion discovery that is significant. I'm paying attention because I'm trying to figure out how much carbon dioxide needs to be cleaned up. An extra 20 years of US oil consumption could be a problem.

Chris

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The Dude on January 27, 2008 - 10:34am Permalink | Subthread | Parent | Comments top

From peakoil.com: Finally, the Bakken makes the national media (NY Times). Lots of links there. Peak oil: Do you want it to occur? detoured into Bakken territory as well.

Also would love to see a TOD piece on this. API of 41 they say.

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