When oil rigs and offshore oil rigs are drilling wells, there are bound to be some problems with the piping along the way. Drilling problems are expensive. Anticipating and understanding piping complications, their causes, and planning solutions, are imperative for cost control, and ultimately effectively hitting the target zone. This article addresses two major problems with drill pipes.
Pipe- Sticking
During the drilling procedure, a drill pipe is deemed stuck, if it is impossible to free and pull out of the hole, without doing damage to the pipe, or without overreaching the maximum hook load on the drilling rig. Mechanical and differential are the two different kinds of p. sticking.Differential Pressure Pipe-Sticking
Differential pressure pipe-sticking is defined as, when a section of the drill string is surrounded with a mudcake; which forms on the pipe's wall of a porous growth while drilling. If the mudpressure grows on the outer wall of the pipe, and is more than the fluid pressure of the formation, then the pipe is considered to be differentially stuck. Some indicators of differential pipe-sticking, while drilling in depleted pressure or porous areas are; not being able to return the drill string, -sometimes while rotating it, or during uninterrupted fluid circulation of the drill or an increase of drag and torque.Mechanical
The causes of mechanical sticking, are as follows: inadequately removing previously drilled cuttings from the annulus, and instabilities of the borehole, such as:- Sloughing
- Hole caving
- Collapse
- Plastic shale
- Salt sections creeping or squeezing.
- Key seating.
Drillpipe Failures
Drillpipe failures can be classified into one of the following:- Fatigue - due to mechanical cyclic loads- which may or may not have any corrosion.
- Collapsing or bursting - due to too much external or internal pressure.
- Parting - due to too much tension.
- Twistoff - due to too much torque
