Slawson: Drilling the Upper Bakken Shale

Again, this is a very tantalizing story sent to me by a reader.  This is a continuation of a discussion that began here.

I am not a geologist, but this is what I think "they" are saying.

The source rock for the Bakken Pool (which includes the Bakken formations and the Three Forks formations) is the upper Bakken formation and the upper Bakken formation.

The oil migrates from this source rock into tight reservoirs: the middle Bakken and the upper Three Forks.

The drillers in the current Bakken boom are concentrating on the two reservoirs: the middle Bakken and the upper Three Forks.

Some argue that the upper and the lower Bakken are both source rock and reservoirs. At the link, the writer discusses the "only" operator who is targeting the source rock as a payzone: Slawson.

There are two important data points according to the geologist at the linked article:

• 90 - 95 percent of the oil in the source rock has not migrated to the tight shale that current operators are targeting
• 5 - 10% of the oil in the source rock is recoverable

For comparison: it is generally accepted that the operators are currently recovering 3 to 15% of the original oil in place (OOIP). The lower, more conservative figures come from government agencies; the upper figures come from some of the operators in the Bakken. I suppose the real answer is somewhere in the middle, though it certainly appears that "best practices" could result in 10% recovery of OOIP.

If the geologist is correct, that 90 - 95 of the "Bakken" oil is still in source rock (which has not been targeted for the most part) and that 5 - 10% is recoverable, it does not take an advanced degree in mathematics to see that the amount of oil that could be recovered from the Williston Basin defies one's wildest imaginations.

As noted above, one operator (Slawson) is targeting source rock. It is my understanding that the technology does not exist or the lack of understanding of how to use existing technology precludes successful wells targeting the source rock.

So the proof will be in the pudding.

According to the linked article, one company is drilling into source rock, the upper Bakken: Slawson.

Slawson says they are producing "some oil" from the source rock (upper Bakken) in three fields, most notably, for me, Squaw Gap in McKenzie County. They say the first Squaw Gap wells were drilled and/or completed in 2007-8 permits, so I will have to go back and check on how those wells are doing. And regardless of how they are doing, one will have to determine if there horizontals are in the upper Bakken or the middle Bakken (it may not be all that easy; I don't know).

In addition, the linked article mentions that permits for six new Squaw Gap wells were issued in mid-April of this year.