Geologic Update Of The Three Forks -- January 25, 2018

For newbies: I'm starting to see more and more Three Forks first bench wells being reported, but still the mix is probably about 90% middle Bakken wells/production and 10% Three Forks first bench 9%. The other 1%: second and third bench.

Also for newbies, previously posted, September 26, 2013; these would be upper Three Forks/first bench wells: Three Forks wells in northeastern McKenzie County five times better than middle Bakken wells -- Lynn Helms.

There is a fourth bench, according to the commercial oil industry, but apparently the academic community sees three benches in the Three Forks, calling the second bench, the middle Three Forks. Or more likely, the lower Three Forks will be comprised of the 3rd and 4th benches.

The middle Bakken is book-ended by the upper Bakken and the lower Bakken, neither of which are significant oil producers, but rather the source rock for the producing payzones.

On the other hand, the Three Forks has four benches: the first bench, fairly well demarcated and a definite payzone; a second bench, now referred to by the academic community as as the middle Three Forks; and a third bench and fourth bench, of which relatively little is known.

That is preamble for this. DMR.ND.GOV has a link to a study of the middle Three Forks, the second bench. It will download as a pdf.  The article is written by Tiothy O. Neshieim. Data points (and this will get quite long):

Part I:

• the study area was pretty much centered between Watford City and Stanley
• wells #26990 and #22388 were in the center of the study area
• oil saturations were typically 25 - 50%; extending from the Bakken down through the base of the middle Three Forks (2nd bench)
• beginning in 2012, various operators began testing the middle to lower portions of the Three Forks formation (2nd, 3rd, and 4th benches)
• the prospective Three Forks reservoir horizons were informally subdivided into four benches, numbered 1 to 4 in descending order
• prior to 2012, most drilling was focused on the middle Bakken
• beginning in early 2015, the NDIC began tracking Three Forks wells
• since then, 180 wells have been drilled and completed in the middle to lower Three Forks formation;  the middle to lower Three Forks have cumulatively produced nearly 20 million bbls of oil ot date (this does not include the upper Three Forks, the 1st bench, which may be more prolific than the middle Bakken in some areas of North Dakota)
• the majority of those middle to lower Three Forks wells targeted the middle Three Forks (2nd bench) -- again, note, we are talking about the middle to lower Three Forks formation, not the first bench which is often referred to as the upper Three Forks
• a significant number of additional, pre-2015 middle to lower Three Forks horizontal wells are also present, but status and cumulative production volumes have yet to bet determined
• currently there is limited geological information available regarding the middle to lower Three Forks
• resource assessments of the Three Forks have ranged from 2 to 4 billion bbls of recoverable oil, but these assessments have been limited to the upper Three Forks [by the way, 2 to 4 billion bbls as an estimate of recoverable oil is so conservative as to be laughable]
• this study reports the preliminary findings of a recently initiated study on the origin and distribution of oil saturations within the middle Three Forks
• the author also examines oil saturations and hydrocarbon production in thee lower Three Forks (3rd and 4th benches)
• hydrocarbons present with the Three Forks are believed to be sourced from the overlying lower Bakken shale, which is considered to be a world class petroleum source rock

Part II:

• the second bench is the middle Three Forks, author
• contains similar rock types to the prolific upper Three Forks (1st bench)

Part III:

• middle Three Forks (2nd bench) oil saturations
• 50+ wells studied
• the middle Three Forks can be further divided into three areas based on oil sats and water sats
• 1st tier area, highest oil saturations: northeastern McKenzie to southeastern Dunn and southwestern Mountrail counties; almost identical to the upper Three Forks, the 1st bench
• a larger 2nd tier: lesser oil sats but still significant
• 3rd tier: water sats increase; oil sats decrease to less than 10%
• 1st tier: correlates with where the lower Bakken shale exists; 20' thick; has reached the greatest level of thermal maturity with respect to oil generation
• 2nd tier: correlates with thinner lower Bakken shale; less thermally mature, but still with the peak oil generation window
• oil saturations of the middle Three Forks appear to be primarily a function of thickness and thermal maturity of the lower Bakken shale
• wells drilled in middle Three Forks to date have mostly been in Tier 1 areas

From the article: