Functions and Components of a Drillstring in Oil Drilling
Classified in Technology
Written at on English with a size of 1.76 KB.
Functions of the Drillstring:
- Transmits rotation to the drillbit
- Exerts weight on the bit; the compressive force necessary to break the rock
- Guides and controls the trajectory of the bit
- Allows fluid circulation for cooling and cleaning
Components of the Drillstring:
- Drillpipe
- Drillcollars
- Accessories including:
- Heavy-walled drillpipe (HWDP)
- Stabilisers
- Reamers
- Directional control equipment
The Kelly:
- Transmits rotation and weight-on-bit to the drillbit
- Supports the weight of the drillstring
- Connects the swivel to the uppermost length of drillpipe
- Transmits drilling fluid from the swivel into the drill string
The Top Drive:
A combined rotary table and Kelly mounted on the rig's swivel, assisting in pipe handling during operations.
Drilling Problems:
- Pipe Sticking
- Lost Circulation
- Hole Deviation
- Pipe Failures
- Borehole Instability
- Mud Contamination
- Formation Damage
- Hole Cleaning
Mechanical Sticking Causes:
- Hole pack off or bridging
- Settled Cuttings
- Shale Instability
- Fractured Rocks
- Key Seating
- Undergauge Hole
Total Losses:
- Maintain proper mud weight
- Minimize annular friction pressure
- Maintain adequate hole cleaning
- Set casing to protect weaker formations
- Treat mud with lost circulation materials if anticipated
If Losses Occur:
- Pump lost circulation materials in the mud
- Seal the zone with cement or other blockers
- Set casing Dry drill (clear water)