What is the purpose of "casing" in drilling?

The purpose of "casing" in drilling primarily centers around maintaining the stability and integrity of the wellbore. When a well is drilled, the surrounding rock formations can be unstable, and the casing provides structural support, preventing the collapse of the wellbore. It also isolates different pressure zones within the geological formations, ensuring that the integrity of the well is maintained throughout the drilling and production processes. This stabilization is essential for safe drilling operations and to prevent any environmental hazards that could arise from wellbore failure.

In this context, while other options may mention aspects that are related to the overall drilling operation, the most crucial function of casing is its role in preserving wellbore stability and ensuring safe drilling practices.