NGWA General Drilling Practice Exam

The use of drilling fluid and casing is essential in preventing borehole collapse during the drilling process. Drilling fluid, also known as mud, serves multiple purposes: it provides hydrostatic pressure that counteracts the earth’s geological pressures, stabilizes the borehole walls, and minimizes the risk of formation damage. The weight of the drilling fluid helps to keep the surrounding geological formations from collapsing into the borehole, especially in unstable or loose soils.

Casing plays a critical role after drilling has reached the required depth. It involves inserting a pipe into the borehole and cementing it in place, which provides structural support to the borehole walls. This prevents the collapse of the borehole and also isolates different aquifers or formations to prevent contamination. Together, drilling fluid and casing provide a dynamic system that maintains the integrity of the borehole throughout the drilling process and afterward, ensuring safe and effective drilling operations.