Wellbore
Wellbore refers to the hole drilled in the ground either on land or offshore to explore or produce oil, gas, or water. A wellbore is drilled using a drill bit through several formation layers and rock types. Drilling fluid is used and is designed to provide the required hydrostatic pressure for ensuring wellbore stability, avoiding the influx of formation fluid, removing drilled cuttings, and cooling downhole. Based on types of formations, pore pressure, and fracture pressure estimations, wellbores are cased with steel casing and cement at predetermined intervals. Part of a wellbore can be left uncased as well depending on the design, rock type, and objectives of the well.