Glossary: Learning about wells

Abandoned well: An oil or natural gas well that is no longer producing. It may or may not have been plugged properly.

Orphan well: An abandoned oil or natural gas well whose owner is bankrupt or can’t be identified.

Hydraulic fracturing: Also called fracking. The injection of water, sand and chemicals under high pressure into oil and natural gas formations. The injection fractures the rock, typically shale, and the now-free oil and gas flow into the well. Combined with horizontal drilling, the practice has revolutionized oil and natural gas production in the United States, while raising environmental concerns.

Horizontal drilling: The practice of drilling laterally through an oil or gas formation. The horizontal length of the well is then hydraulically fractured, greatly increasing the amount of oil and natural gas produced by one well.

Casing: Metal pipe, usually steel, that lines an oil or natural gas well. The surface casing protects groundwater from contamination. The production casing isolates oil and natural gas from other geological formations and carries it to the surface. Early wells had wooden casings.

Plug: A physical barrier placed in a well to prevent oil, natural gas, freshwater and brine from flowing between different underground layers. Many regulators require plugs to be set across oil- and gas-producing formations, as well as groundwater zones. Cement is commonly used to plug wells. Early plugging materials included dirt and logs.

Brine: Salt water trapped in the earth’s crust, often found with oil and natural gas deposits. In addition to salts, brine can contain heavy metals and radioactive material. Brine is often injected underground for disposal.

Magnetometer: A device that measures magnetic fields. It can detect anomalies caused by metal well casings. Magnetometers can be carried by hand or fixed to a helicopter.

Ground-penetrating radar: A device that uses electromagnetic waves to reveal images of objects beneath the earth. Ground-penetrating radar is used in fields such as archeology, construction and surveying.

Shane Hoover