Oil Spill Glossary Berm, Dispersants, Static Kill, and more A-Q| R-W Annulus The space between the pipe and the wellbore. Biodegradation The breaking down of substances by microorganisms, such as oil-hungry Alcanivorax, which use the substances for food and generally release harmless byproducts such as carbon dioxide and water. Berm A wall or barrier of sand usually used to protect against flooding along coasts, used to stop oil from washing up on Gulf Coast beaches. Boom A temporary floating barrier used to contain an oil spill. Blowout An uncontrolled flow of reservoir fluids into the wellbore, and sometimes catastrophically to the surface. A blowout may consist of salt water, oil, gas or a mixture of these. Blind shear ram The part of the blowout preventer that can completely seal the well. Blowout preventer (BOP) A large valve at the top of a well that may be closed in the event of a problem. Bottom kill A procedure in which mud and cement are pumped from deep underground to seal the well permanently. Containment cap A collection device engineered to create a seal over an open pipe atop the blowout preventer to funnel leaking oil up to a tanker ship floating above. Crude oil Unrefined petroleum or liquid petroleum. Dispersants Chemicals, such as Corexit, used to break down spilled oil into small droplets. Fossil fuels Fuel, such as oil, formed in the earth from plant or animal remains. Junk shot One method of temporarily plugging an oil leak by shooting material such as shredded tires and golf balls into the broken wellhead. Loop current Flow of warm ocean water that steers Gulf waters toward Florida. Moratorium Suspension of activity. A-Q|R-W Relief well A secondary well drilled to intersect the leaking main well, allowing engineers to intercept the oil flow from the reservoir below and pump in cement and heavy fluids to stop the leak. Rig Machine used to drill a wellbore. Riser pipe The pipe that connects an underwater wellhead to the drilling rig floating on the surface of the ocean above. Skimmers Devices, such as boats, used to remove oil from the water's surface. Slick A thin film of oil on the water's surface. Static Kill A method of spill containment which involves pumping mud and cement into the damaged well to prevent more oil from leaking into the ocean. Tar balls Dense, black sticky spheres of hydrocarbons; formed from weathered oil. Top hat A containment device used to cap off the oil. Top kill A temporary method of sealing an oil well involving pumping dense mud into the blowout preventer under such high pressure that it forces the leaking oil back into the ground. Wellbore A hole drilled for the purpose of extracting oil. Wellhead A system of spools, valves and assorted adapters that provide pressure control of a production well. The wellhead is the component at the surface of the wellbore to which the apparatus for extracting the oil is attached. The blowout preventer is at the wellhead.