Bent sub:

Its purpose is to deflect the downhole motor off vertical to drill a directional hole.

See drill stem.

Terms Related to Bent sub

• Dyna-drill

  Trade name for a downhole motor driven by drilling fluid that imparts rotary motion to a drilling bit connected to the tool, thus eliminating the ...

• Directional drilling

  1. Intentional deviation of a wellbore from the vertical. Although wellbores are normally drilled vertically, it is sometimes necessary or advantageous to drill at an ...

• Sub

  A short, threaded piece of pipe used to adapt parts of the drilling string that cannot otherwise be screwed together because of differences in thread ...

• Drill collar

  A heavy, thick-walled tube, usually steel, used between the drill pipe and the bit in the drill stem to provide a pendulum effect to the ...

• Turbodrill

  A downhole motor that rotates a bit by the action of the drilling mud on turbine blades b built into the tool. When a turbodrill ...

• Bottom hole assembly

  (bha) the lower portion of the drillstring, consisting of (from the bottom up in a vertical well) the bit, bit sub, a mud motor (in ...

• Drill stem safety valve

  A special valve installed below the kelly. Usually, the valve is open so that drilling fluid can flow out of the kelly and down the ...