Drillers also use sensors to detect particularly promising rock intervals within the formation, and are able to move the drill string up or down, left or right as they drill through the horizontalsection to target those intervals.
The technology employed is so advanced and exacting that drillers today can hit a target at the end of a drill string that is 10, 000 feet vertical with a mile long horizontalsection that is no more than a few inches in diameter.