Definition - What does Casing Scraper mean?
A casing scraper is a wellbore clean-up tool with a blade-like attachment used to remove filter cake, scale, debris and other obstructions from the internal diameter of a casing pipe. This keeps the casing pipe clean and allows downhole tools to run smoothly within the casing. Most casing scrapers are adapted to suit any casing size and drill pipe combination.
A casing scraper is generally run on tubing or drill pipe and routinely used in workover operations to ensure a clean wellbore before reinstalling the completion string. The cleaning of the casing internal diameter (ID) is a critical part of successful wellbore completion, especially for fluid filtration and the proper setting of sealing elements used in downhole tools.
Casing scrapers are designed to provide 360° coverage to ensure complete clean-up of rust, perforation burrs, scale, debris, cement, or filter cake that may be stuck to the casing pipe.
A well-executed clean-up removes any residue that can block screens and pores which can otherwise reduce wellbore productivity. It also helps reduce non-productive time during wellbore completion.
Casing cleanup is necessary whether a new well is being drilled or an old well is being reworked and is a critical part of successful completion operations. Obstructions in the casing can interfere with the operation of downhole tools during drilling, wireline jobs, fishing, or completion.
For packers, patches, and similar tools that require a grip on the casing, a clean ID is necessary for a good grip. In such areas, the casing scraper is run two or three times to ensure that the wall of the casing is clean and smooth.
Trenchlesspedia explains Casing Scraper
During a drilling operation, the casing wall gets clogged with mud, cement, rust, scale buildup, and other obstructions which can hamper the operation of downhole tools. The casing scraper removes these deposits including burrs and irregularities in the casing ID.
For the life of a wellbore, debris is a recurring issue and ranges from drilling fluid residue to perforation fragments. Operating downhole tools in a casing that is not cleaned can damage completion equipment, cause production losses, and damage the formation.
Casing scrapers can:
- Remove paraffin, mud, and hardened cement
- Remove burrs and nicks caused by fishing tools and drill bits
- Take care of dents caused by tool mishandling
- Remove burrs from perforations
- Remove bullets embedded in the casing
Scraper Construction and Operation
In general, casing scrapers consist of a single scraper body, a blade retainer, scraper blades with springs and retainer rings. The body of the scraper is splined and locks the blades into the body to ensure safety. The blades are made of high-quality steel for durability and proper scraping. The blades can cover 360° surface area and are designed with a long taper to pass easily through casing connections.
The springs in the blade keep the blade firmly pressed against the pipe and allow it to compress and depress during scraping operations. A blade retainer and retainer rings hold the blades and springs in place on the body of the scraper. The scraper is run into the casing or tubing by rotation or spudding.
A well-maintained casing scraper will ensure long service life and proper casing cleanup with each operation. It is recommended to completely disassemble and thoroughly clean the casing scraper after each use. Parts that are worn or show signs of damage should be immediately replaced.