In drilling, a casing scraper is a downhole tool with blades that cleans the inside of wellbore casings by removing obstructions like scale, cement, rust, burrs, and debris, ensuring smooth passage for other tools (like bits, packers, or wireline) and preventing issues during well completion, workovers, or fishing jobs, crucial for well integrity and efficiency.
How They Work
- Mechanism: Scrapers use spring-loaded, cast steel blades or brushes that expand outward to contact the casing wall.
- Operation: They are run on drill pipe or tubing and work by rotation (rotary) or by moving up and down (reciprocating/spudding).
- Cleaning Action: The blades mechanically scrape and dislodge buildup from the casing’s inner surface.
Key Functions & Benefits
- Removes Obstructions: Cleans rust, scale, paraffin, cement sheath, perforation burrs, and mud.
- Ensures Tool Passage: Allows tools like drill bits, packers, gauges, and logging tools to run freely to the bottom of the hole.
- Improves Well Integrity: Cleans the casing ID for better cementing, stimulation, or fishing operations.
- Versatile: Can be used during drilling, well cleanup, fishing, and workover operations.
Types
- Mechanical Scrapers: The most common, using blades/brushes.
- Non-Rotating Scrapers: Used for specific applications where rotation isn’t desired.
When Used
- After drilling to clean the casing before completion.
- During workovers to remove scale or paraffin.
- Before running packers or setting plugs.
