The rock formation consists of three members: lower
, middle
, and upper shale. The shales were deposited in relatively deep marine conditions, and the dolomite was deposited as a coastal
bank during a time of shallower water. The middle dolomite member is the principal oil reservoir,
roughly two miles (3.2 km) below the surface. Both the upper and lower shale members are organic-rich marine shale.
in the Bakken average about 5%, and
permeabilities are very low, averaging 0.04 millidarcies—much lower than typical oil reservoirs.
[4] However, the presence of horizontal fractures makes the Bakken an excellent candidate for
techniques in which a well drills along the extent of the rock layer, rather than punching a hole vertically through it. In this way, many thousands of feet of oil reservoir rock can be penetrated in a unit that reaches a maximum thickness of only about 140 feet (40 m).
[5] Production is also enhanced by artificially fracturing the rock,
[6] to allow oil to seep through for centralized collection.
08-23-2008, 02:51 PM
Bloody Pingu Champion!
Bakken_Formation
Linear Mode
