Continental Resources Inc.’s news Monday of a successful test of the Three Forks 3 bench proves yet a fourth layer of horizontal oil production from the prolific Williston Basin, which already hosts abundant and growing production from the Bakken and Three Forks 1 bench.

In a 24-hour test, Charlotte 3-22H flowed 953 barrels of oil equivalent (BOE) per day — mostly oil — from a 9,701-foot lateral with 30 frac stages at 21,324 feet below the surface. The test was at 1,700 psi with a 28/64 choke, and the well had been online for 15 days upon Continental’s announcement.

Drilled in McKenzie County, N.D., in the heart of the Bakken play, Charlotte 3 is near Continental’s Charlotte 2-22H well, which tested the Three Forks 2 bench last year and has made 87,000 BOE in its first 10 months online. Since that Three Forks 2 test, ConocoPhillips has drilled a Three Forks 2 test as well: Sunline 11-1TF-2SH, which has made 85,000 BOE in six months.

Continental proved the Bakken play, which targets the Middle Bakken formation that is trapped between two shales, in 2004, and proved the Three Forks 1 bench in 2008.

The TF2 trial, Charlotte 2, had tested 1,140 BOE per day, mostly oil, from a 9,700-foot lateral after 30 frac stages on a 26/64-inch choke.

“If the Charlotte 3-22H continues to perform in line with the second-bench Charlotte 2-22H, it will be the first well to establish commercial production in the third bench,” Oklahoma City-based Continental reports.

Harold Hamm, Continental chairman and chief executive officer, adds, “This could be a real game-changer.” The company plans 14 wells by year-end 2013 to further test Three Forks 2 and 3, and the company also plans in the coming year to test the fourth of four Three Forks benches: Three Forks 4.

Based on Middle Bakken and Three Forks 1 findings, Continental had estimated two years ago that the Williston Basin play could yield 24 billion BOE and had 557 billion of original oil in place.

“… With the addition of oil found in the lower Three Forks benches (the TF2, TF3 and TF4), the company now estimates the field has 903 billion barrels of original oil in place …,” the company reports.

Jack Stark, Continental senior vice president, exploration, adds, “The results are very encouraging and indicate there may be upside to our estimate of 24 billion BOE of recoverable reserves for the Bakken (petroleum system).”

In the January 2012 issue of Oil and Gas Investor, Stark explained that the Three Forks 1 and 2 tests also proved that these reservoirs produce independent of each other and independent of the Middle Bakken. Essentially, this means each well landed in any of the three Three Forks zones produce oil that isn’t simply draining each other or the Middle Bakken. Further Three Forks 3 tests are expected to show this as well, he said.

Each of the four Three Forks benches is trapped between layers of shale. The 15,000-square-mile Bakken petroleum system — incorporating three pervasive layers of Bakken, the occasional Sanish, which sits atop Three Forks in some areas, and four layers of Three Forks— are sealed by the Lodgepole limestone at the top and uber-tight anhydrides of Birdbear (aka Nisku) at the bottom, resulting in an overpressured system between the two normal-pressured seals.

Stark noted too that, from core samples, each Three Forks bench is slightly less thick, with the first being about 50 feet and the fourth being about 30 feet. Also, the four benches appear to be ubiquitous under the Middle Bakken. However, their aerial extent may become smaller across the map as the drillbit gets deeper; essentially, that means the geographic footprint of each is less enormous than that of the productive Middle Bakken’s extent. They’re bowls within bowls, Stark explained, but, unlike those stacked on a kitchen shelf, these are in reverse — from largest to smallest from top to bottom, rather than smallest to largest.

Jefferies & Co. E&P analyst Subash Chandra says of the new Three Forks 3 findings, “Overall, although the (initial BOE/day) result may not have ‘knocked it out of the ballpark,’ we see it as a solid first step to (Three Forks) third-bench exploration.

“Rates could improve further along the learning curve. Continental was able to improve rates with its first-bench tests back in 2008. The first Three Forks 1 well recorded a seven-day rate of 693 BOE per day. The rate improved to 1,000-plus BOE per day by the second well.”

He concludes, “The first (Three Forks 3) result indicates that there’s a good chance the third bench could become a resource comparable to the Middle Bakken, Three Forks 1 and Three Forks 2.”

NOTE: For more on the Three Forks 2, 3 and 4 benches, see “Emerging Plays,” January 2012, Oil and Gas Investor.