The Sanish vs the Pronghorn -- The Bakken, North Dakota, USA

Update

According to Whiting, NDIC recently renamed "Sanish Sand" the "Pronghorn Sand":

On Slide 8, our 2 typical production profiles for non-Sanish field, Bakken or Pronghorn sand/Three Forks wells. Note the NDIC has recently renamed the Sanish Sand the Pronghorn Sand. This is the zone we drill in across Lewis & Clark and Pronghorn. The production profile EURs range from 600,000 BOEs to 350,000 BOEs, which we believe reflects the range of our Lewis & Clark, Pronghorn, Hidden Bench, Tarpon and Cassandra Prospect wells. Average well cost is estimated at $7 million. As you can see, these wells have excellent economics at current oil prices.

I don't find any evidence of this change at the NDIC website yet, but I could have missed something. It will be interesting if we see reflection of this change by end of 2012. My hunch: it will still be confusing. I say that because the statistical data through 2010 shows these six formations as separate formations: Bakken, Bakken/Three Forks, Three Forks, Sanish, Lodgepole/Bakken, and Lodgepole.

I have my own ideas on how to separate out these formations but my opinion will only confuse matters so I will keep them to myself. But when I see the Bakken, Bakken/Three Forks, Three Forks, Sanish, Lodgepole/Bakken, and Lodgepole and then then hear that NDIC has changed "Sanish Sand" (which, by the way, is not even in that list of six) to "Pronghorn Sand" it's anybody's guess how to sort this out.

Original Post

Someone asked earlier how much different is the Sanish Three Forks from the Pronghorn Three Forks, suggesting perhaps that the Pronghorn was just a different name for the Sanish, but in a different geographic area?

This is my take on it, subject to change as more information comes out.

First, the "Sanish" is a confusing term. See this link: a geologist's take on the Sanish, April, 2011.

 The term Sanish is used in several different contexts in North Dakota. Confusion over the name led one local geologist to declare, “The Sanish should vanish,” Sonnenberg said.

Now look at how Whiting separates out the Sanish in their November, 2011, corporate presentation, slide 14.  In their presentation, Whiting looks at four prospects:

• Sanish Bakken
• Sanish Three Forks
• Lewis & Clark Pronghorn
• Hidden Bench

Based on other sources and this slide, the "Sanish" is not a formation. The "Sanish" is a geographic location, specifically associated with the Sanish oil field, north of the reservation and west of the Parshall oil field.  In that geographic location, in that Sanish oil field, one finds the entire stratigraphic column, including the upper, middle, and lower Bakken formations, as well the upper and lower Three Fork formations.

On the other hand, the Pronghorn is a sub-formation of the Three Forks, located between the lower Bakken and the "upper" Three Forks.

Just as the one, two, three, or possibly four "benches" below the Three Forks are sub-formations, the Pronghorn is a sub-formation of the upper Three Forks.

The Sanish is not an additional sub-formation; it is a geographic area in North Dakota.

The Pronghorn, and the "benches" are new sub-formations, new pay zones. The Pronghorn is not necessarily located throughout the Williston Basin.

The question asked earlier had to do with the geology of the Sanish compared with the geology of the Pronghorn. I don't think that can be asked, based on my very limited understanding of the terms.

For me, bottom line: the Sanish is a geographic term associated with the Sanish oil field; the Pronghorn is a new, oil-producing pay zone. I cannot comment on the geology of the various formations.