1. n. [Reservoir Characterization]

The angle at which a wellbore diverges from vertical. Wells can deviate from vertical because of the dips in the beds being drilled through. Wells can also be deliberately deviated by the use of a whipstock or other steering mechanism. Wells are often deviated or turned to a horizontal direction to increase exposure to producing zones, intersect a larger number of fractures, or to follow a complex structure.

See related terms: bed,  deviation survey,  dip