A horizontal oil well can reach oil that a straight-down well cannot.
It goes down about 20,000 feet, then turns sideways and goes up to three miles through the rock.
When it reaches the right spot, the well is filled with sand and water is pushed in with high pressure to crack the rock.
This is called fracking.
The cracks let more oil flow into the well so it can be pulled up.
One well can reach a lot more oil this way.
The risk of hitting no oil is never zero, but with horizontal wells it is very low.
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