Hydraulic Rotary Boring Method

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Rotary Drilling

Hydraulic Rotary (Rotary Boring) Method

The hydraulic rotary or rotary boring method is widely used for water wells and deep oil wells. This technique works efficiently in both hard rock and unconsolidated formations. A major advantage of this method is that the drilling rate remains consistent regardless of the depth of the well.

In this system, drilling is performed by a rotating bit connected to the lower end of a hollow steel drill pipe. The drill pipe is connected to a square-section rod known as the kelly, which fits into a rotating table at the surface. As the table rotates, the drill pipe and bit rotate, cutting through the formation.

Components of a Rotary Drilling Rig

• Derrick or mast structure
• Rotating table or top-drive system
• Kelly (square or hexagonal rod)
• Mud pump for circulating drilling fluid
• Hoist system
• High-strength drill pipes (typically 6 m each)

How the System Works

• The rotating table turns the kelly, drill pipe, and drilling bit.
• Drilling fluid (mud) is pumped down the pipe and exits through the bit nozzles.
• The mud jets clean the bit face and carry rock cuttings upward.
• The fluid returns to the surface via the annulus and enters the settling pit.
• Cuttings settle out, and the mud is recirculated back into the system.