Mechanical Pipe Sticking
1 Introduction To Mechanical Pipe Sticking:Mechanical Pipe sticking is when any part from the Drill String such as Drill Pipe, Heavy Weight Drill Pipe HWDP, Drill Collars, Drilling Bit or Bottom Hole Assembly BHA is stuck in a borehole due to mechanical reasons as cutting accumulation, junk, large cement cutting and changing Drill String geometry and cannot be recovered from the bore without damage to the drill pipe. It can occur because of a variety of reasons as will be discussed below.
2 What Is The Real Mechanical Stuck Pipe Causes
We will discuss below the main causes for Mechanical Stuck Pipe and you can easily visit each link to have more details about the tips for preventive actions, indications and first action for each type of the mechanical stuck pipe.
Key Seating As a Mechanical Stuck Pipe Cause
Key Seating is caused by the Drill Pipe rotating against the bore hole wall at the same point and wearing a groove or key seat in the wall. During a trip out of the hole, the Bottom Hole Assembly BHA may be pulled into one of these grooves, which may be too small for it to pass though. This type of sticking is likely to happen in a soft formation while dropping angle.
Key Seating can also occur at the casing shoe if a groove is worn in the casing and cause a mechanical stuck for casing pipes.
Undergauge Hole Mechanical Stuck Pipe
|Undergauge Hole Stuck Pipe|
If it was decided to run quickly without reaming, the Drilling Bit can jam in the Under gauge hole and become stuck.
Ledges and Doglegs
|ledges at formation changes|
Closely spaced ledges decreases the effective diameter of the hole and produce a "shouldered" hole surface. The stiff casing string requires a smooth, more in-gauge hole diameter for free passage and not to stuck.Also Doglegs can be defined as following: While drilling a well bore, the characteristics of the rock cause the Drilling Bit to be deflected and can result in a change in Azimuth. Likewise when drilling with a directional Bottom Hole Assembly BHA, sudden changes in angle can cause a kink in the well bore direction. Sharp deviations in wellbore direction are called doglegs.
Metal Junks Dropped Or Parted Cause Mechanical Stuck Pipe
- Due to poor housekeeping on the rig floor.
- The hole cover not being installed.
- Downhole equipment failure.
Collapsed Casing Mechanical Stuck
through decreased wall thickness. Collapse is often discovered when the Bottom Hole Assembly BHA is run into the hole and hangs up inside the casing.
Mechanical Stuck Pipe In Cement Blocks
|Cement Blocks Stuck|
Mechanical Stuck Pipe In Green Cement
When the Drill String is inadvertently run into cement, the cement can flash set. The top of the cement may be higher than prognosed. The increase in pressure generated by the surge of the Bottom Hole Assembly BHA causes the cement to flash set.
Circulation is attempted with the bottom of the Drill String in soft cement.
The increase in pressure causes the cement to flash set.
A high penetration rate is used when cleaning out recently set cement, below which is un-set cement which flash sets.