What is described as a cylinder of rubberlike material which is run on a tubular string down hole and is compressed to expand and seal the well at that level?

• A. Sealing plug
• B. Tubing hanger
• C. Packer
• D. Swelling sleeve

Answer: (C)

A packer. It’s run on a tubular string down the well and, when set, its elastomer (rubberlike) element is compressed so it expands radially to press against the wellbore or casing. That expansion creates a seal at that depth, isolating the interval for operations like perforating, testing, or production. The mechanism relies on the elastomer expanding once compressed by the setting action, which is exactly what the description describes.