In oilfield terminology, which device is expanded to seal a downhole zone during completion?

In oilfield terminology, which device is expanded to seal a downhole zone during completion?

• A. Packer
• B. Cement plug
• C. Subsurface safety valve
• D. Cementing plug

Answer: (A)

The thing being tested is the idea of an expandable sealing device used in completion work. A packer is placed in the well and, when activated, its sealing elements expand to press against the casing or borehole wall, creating a fluid-tight barrier in the annulus. This allows isolating a specific downhole interval so operations like perforating, testing, or cementing can be performed without fluids moving between zones. The expansion mechanism can be hydraulic, mechanical, or electric, and packers can be permanent or retrievable. In contrast, a subsurface safety valve is a downhole safety device that controls flow in the production string, not a tool used to seal a zone during completion. Cement plugs and cementing plugs form barriers through cement hardening or placement, not by an expanding mechanism, so they don’t fulfill the same function as an expandable packer.

The thing being tested is the idea of an expandable sealing device used in completion work. A packer is placed in the well and, when activated, its sealing elements expand to press against the casing or borehole wall, creating a fluid-tight barrier in the annulus. This allows isolating a specific downhole interval so operations like perforating, testing, or cementing can be performed without fluids moving between zones. The expansion mechanism can be hydraulic, mechanical, or electric, and packers can be permanent or retrievable. In contrast, a subsurface safety valve is a downhole safety device that controls flow in the production string, not a tool used to seal a zone during completion. Cement plugs and cementing plugs form barriers through cement hardening or placement, not by an expanding mechanism, so they don’t fulfill the same function as an expandable packer.