Filloon: Three Forks -- Great Potential -- The Bakken, North Dakota, USA -- SeekingAlpha.com

Note: the "Three Forks" is a formation just below the Bakken formation. The Bakken formation is further divided into the upper, middle, and lower Bakken.  In 2011, operators started talking about four benches "below" the Three Forks.  The Bakken formations and the Three Forks formations are part of the Bakken Pool. The "Sanish" or the "Three Forks Sanish" is a specific part of the Three Forks found in western Mountrail county, where the Sanish oil field is located. 

Over time operators are becoming more consistent when referring to the various Three Forks formations. The "legacy" upper Three Forks formation is TF1; the second bench is TF2; the third bench is TF3; and, the lowest bench is TF4. As of 2014, TF4 has not been tested widely. 

Updates

August 27, 2021: at this post.

• Three Forks, second bench
• Three Forks, third bench
• sand, fracking sand in North Dakota
• landslides in North Dakota

January, 2021: the lower Three Forks formation (third bench), Bakken-Three Forks petroleum system, overview of development history and future potential; Timothy O. Nehsheim, GeoNews, DMR, North Dakota, link to source article. Link to blog post.

January 25, 2018: a geologic update of the middle- to lower-Three Forks, ND geologic survey. A must-read.

September 26, 2013: Three Forks wells in northeastern McKenzie County five times better than middle Bakken wells -- Lynn Helms

June 23, 2013: the 2013 USGS Survey -- The Three Forks

May 24, 2010: Source Rock for the TFS

January 6, 2010: Continental Resources (CLR) reports six wells that targeted the TFS; excellent results.

Original Post

Link at SeekingAlpha.com here.

The article is very detailed and I won't go through it now. Maybe later for future reference.

Suffice to say:

Filloon: The Three Forks could be a bigger story than the middle Bakken. At its thickest point it is 270 feet thick, compared to the middle Bakken at 90 feet.

Yup. See an earlier (November, 2011) post here. 

Something tells me ONEOK did the math.

*******************

This is from Mike's article linked above. I am providing bare details. Go to the link for the full story.

Data points:

Upper Bench

• the Three Forks is commercial throughout a good portion of the Williston Basin
• the thinnest portion of the upper Three Forks is in the northwest portion of the Williston Basin in Montana; it thickens significantly to the east and south
• the further north in Williams County, the thinner the upper Three forks
• a notable well: Magnum Hunter's Thomte, just a few miles from the Canadian border
• in McKenzie County, Three Forks seems thicker in the south and east
• gets thicker into northern Billings and western Stark counties
• extends into South Dakota

Second Bench

• Continental Resources testing the second bench
• of the few wells drilled so far into the second bench, it appears that bench is consistent throughout the Basin
• if the second bench is like the first, an additional four wells/pad possible
• Hess has planned its first 12-well pad, and an additional 6 locations could be possible with the second bench --> 36-acre spacing without wells in the third or fourth bench

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.

AAPG Article on The Three Forks Formation

Link here. Published April, 2011.

The article appears to be based on an interview with Steven Sonnenberg. Sonnenberg is professor of petroleum geology at the Colorado School of Mines in Golden, CO, and heads the school's Bakken Research Consortium, with 20 member companies and a grant from the National Energy Technology Laboratory.

Current thinking puts recoverable oil from the Bakken Shale at just over two billion barrels, and from the Three Forks Formation at just under two billion.

The U.S. Geological earlier estimated mean, technically recoverable, undiscovered volumes in the Bakken system of 3.65 billion barrels of oil, 1.85 trillion cubic feet of associated/dissolved natural gas and 148 million barrels of natural gas liquids.

Sonnenberg said the main source rock for the upper Three Forks is the lower Bakken Shale, although where the lower and middle Bakken thin in the southern Williston Basin, the upper Bakken is the main source.

The Three Forks underlies the Bakken, separated by the Sanish Formation.

The article, thus, clarifies the Sanish formation a bit more. 

(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.)

I was happy to read that; I wasn't the only one confused by the "Sanish" term.