How is a geothermal well drilled?
• High-temperature, Water-dominated Reservoirs The methods and equipment used to drill geothermal wells in high-temperature, water-dominated reservoirs are very similar to those used to drill oil and gas wells. Conventional rotary drilling rigs and drilling equipment are used and drilling fluid—also called drilling mud—is circulated through the well to bring the cuttings back to the surface and to cool the well. • Steam-dominated Reservoirs Because conditions in steam-dominated reservoirs differ significantly from those in water-dominated reservoirs, drilling procedures do as well. In a steam-dominated reservoir, a typical well is drilled with drilling mud to a point above the first anticipated steam entry. Then high-pressure air is used. Mud would plug the fractures and pore spaces in the formation and much less steam would be produced. • Low-temperature Water-dominated Reservoirs As conditions in low-temperature, water-dominated reservoirs usually are similar to those found when dril
