What is the function of well casing?

• A. Material used to fill in voids around well casing.
• B. What must be installed to displace air from the well?
• C. Steel pipe cemented into the wellbore and prevents the caving in of the hole, protects fresh water sands, confines production to the wellbore, and controls formation pressure.
• D. Elevation or level of the water table in a well when the pump is not operating.

Answer: (C)

Well casing is the protective lining placed inside the drilled borehole and cemented in place. Its main job is to keep the hole from collapsing, providing structural support for the well as it produces. It also isolates different underground layers, which protects fresh groundwater sands from coming into contact with production fluids and prevents cross-contamination between formations. By enclosing the production zone and forming a stable conduit, it helps confine production to the wellbore and supports formation-pressure control by creating a sealed barrier in the annulus. So the function is to stabilize the borehole, protect freshwater zones, confine production to the wellbore, and aid in managing formation pressure. The other options describe materials around the casing, air-displacement steps, or water-level measurements that aren’t the function of the casing itself.