HOW - Hydrofracking: What Everyone Needs to Know - page 21

the bit and the rig, allowing the bit to change direction, from drilling vertically to
horizontally. 9
Al Granberg/ProPublica
Operators on the surface carefully monitor instruments lowered into the well
to monitor the azimuth—the measurement of angle in a spherical context, like the
earth—and orientation of the drilling, and steer the drill bit underground. 10 Three-
dimensional seismic imaging technology has made it easier for drillers to identify
“sweet spots,” places where gas has collected in large reservoirs. Once the borehole
has been steered into the shale, straight-ahead drilling resumes, moving horizont-
ally through thousands of feet of shale rock.
The combination of directional drilling and hydraulic fracturing works well in
places like the Marcellus Shale and Bakken Formation, which were not productive