Geology

The Bakken formation has received considerable recognition for its oil production capabilities. Oil was
discovered in this formation in 1951 but production was difficult to achieve at that time. Technological
developments and improvements since then have given operators the capabilities in recent years to develop the formation. In April 2008, the United States Geological Service (USGS) released a report estimating the amount of oil recoverable with current technology ranged from 3.0 to 4.3 billion barrels. At the same time, the State of North Dakota also released a report estimating recoverable oil at 2.1 billion barrels.

Other industry estimates place the total oil available, which includes oil that cannot be recovered with current technology, at 18 billion barrels. The USGS has recently released a report further reassessing the amount of technically recoverable oil in the Bakken formation. According to the report (USGS FS 2013-3013, released April 2013) “…the USGS estimated mean undiscovered volumes of 7.4 billion barrels of oil, 6.7 trillion cubic feet of associated/dissolved natural gas liquids in the Bakken and Three Forks Formations in the Williston Basin Province of Montana, North Dakota, and South Dakota.”

There are several formations below the subsurface of the Bakken formation known commonly as the Three Forks. Evaluative wells have already been drilled to these “benches” of the Three Forks. Operators have recently begun exploratory drilling into these benches. Several operators have announced plans to evaluate high density drilling possibilities to these benches. The graphic below shows a development pilot program Continental has announced as part of its Three Forks drilling program.

Horizontal Drilling

Horizontal or directional drilling has revolutionized the way the oil and gas wells are being drilled in the Williston Basin. The reason that horizontal drilling is changing the oil and gas business is that a well drilled sideways through a formation that contains oil and gas will produce many more times that of a vertical well. A vertical well will only penetrate a limited area of the productive zone, whereas a well drilled horizontally may penetrate up to 10,000′ of the zone. This also means that previously tight shale formations such as the Bakken Formation can result in prolific production.

The Bakken Formation has poor porosity which reduces the ability of the gas and oil to flow out of this horizon. Recently, horizontal drilling of lateral holes combined with hydraulic fracturing (“fracking”) has resulted in substantial production from thick formations that have poor porosity. Fracking is a procedure whereby packers (plugs) are set every 250′ to 300′ and up to ten 2,000 horsepower hydraulic pumps deliver high pressure fluids that contain a high percentage of round ceramic beads are utilized as propellant and keep the fissures and fractures open along the bedding-planes that are created by the high pressure fluids. The fissures and channels created by the high pressure fluid and held open by the ceramic beads that are left behind; provide a pathway to allow the gas and oil to flow into the drill hole.

New Technologies

Two new technologies are currently being used to enhance horizontal drilling: Log While Drilling (LWD) and Drill String Radar (DST).

LWD uses long sensors which read gamma radiation given off by the formation, which provides real time information to the drillers and this information is gathered and assists drillers to drill in the optimum sections of the formation.

DST provides information to the driller on the surface as to what direction and angle the well is being drilled. The combination of the two technologies greatly assists keeping the drill bit in the optimum location within the Bakken Formation.