Definition - What does Deviated Hole mean?
A deviated hole is a wellbore that is inclined and it's not in a vertical direction. Ideally, a deviated hole is drilled on purpose in a horizontal way, far away from the vertical. However, a hole can get deviated on its own as well, due to the cracks formed in the rock formation caused by the fracturing (drilling) process. Either ways, a deviated hole is a borehole that is inclined and is at an angle from the predetermined borehole placement from the vertical.
Petropedia explains Deviated Hole
In petroleum engineering, a borehole is planned in advance so as to get started with the oil drilling program. Drilling rigs are set up on the location and a vertical well path is followed to drill the oil well and reach the reservoir. When the drilled hole deviates, i.e., leans off from the actual vertical well path, it is called as deviated hole. If the hole gets deviated accidentally during the process of drilling, it is referred to as crooked hole. However, the oil well is also prone to deviate on its own due to the cracks, pressure, weight and many other factors.