Comment: 07:00 - 08:17 (01:17)
Source: Annenberg/CPB Resources - Earth Revealed 26. Living With Earth, Part II
Keywords: "Anthony Marino", Arco, Bakersfield, California, oil, deposit, well, drilling, reservoir, "sedimentary rock", sandstone, limestone, pressure, gas, "rock formation"
Our transcription: Arco's site in Bakersfield, California, is thought to contain over 100 million barrels of oil in a deposit that is roughly 38 feet thick and 2,000 feet long.
Although more than 1,000 wells have pierced this reservoir, a significant portion of the oil still remains underground.
The oil actually isn't contained in huge pools underneath the ground.
Really, it's contained within these very small pore spaces of sedimentary rocks like sandstones and limestones.
The flow openings through these rocks are really quite small, and it takes a tremendous amount of pressure to force the oil and gas through the pore spaces in the rocks.
In a new untapped field, the natural pressure of the formation may be enough to drive the oil to the surface.
But as wells draw oils from the ground, that pressure drops and extraction becomes more difficult.
Typically, as much as two-thirds of the oil remains underground because of this drop in pressure.
Geology School Keywords