How is groundwater protected when an oil, gas, or injection well is being drilled?
When a well is being drilled, drilling fluid, a specially designed liquid, is pumped through the drill pipe, and circulated out through the wellbore, and back to the surface. One function of the drilling fluid is to lift rock cuttings out of the wellbore and to the surface. Drilling fluid also serves to cool the drill bit, and to counteract downhole formation pressure keeping reservoir fluids and groundwater from entering the well bore and preventing them from mixing. When a well is completed, casing is cemented in the wellbore (watch a movie), keeping reservoir fluids and groundwater from mixing.
