Glossary
Tank Battery Glossary
Plain definitions of the words used at tank batteries, SWD sites and across our Field Fixes.
Tank battery
A group of tanks and equipment at a well site or facility where oil, gas and water from the wells are separated, stored and measured before they are sold or sent for disposal.
AST (aboveground storage tank)
A storage tank that sits on the ground surface rather than buried. Most oilfield oil and water tanks are ASTs, and they can be open top or closed top.
Oil pad (solid pad)
A layer of oil, wax and sludge that builds up on top of the water in a tank. Over time it can harden into a thick solid pad that is hard to pump out and takes up tank space.
Skimming
Removing the oil that floats on top of the water in a tank, so the oil can be recovered and sold and the water can be sent on with less oil in it.
Produced water
The salty water that comes up out of the ground along with oil and gas. It usually carries some oil and dissolved solids and has to be treated, reused or disposed of.
Saltwater disposal (SWD) well
A well used to inject produced water deep underground into a rock layer that can hold it, far below drinking water zones.
UIC (underground injection control)
The regulatory program that permits and oversees wells that inject fluids underground. In Texas the Railroad Commission runs it for oil and gas wells, including disposal wells, which are Class II wells.
RRC (Railroad Commission of Texas)
The state agency that regulates the oil and gas industry in Texas, including drilling, production and disposal wells. Despite the name, it no longer regulates railroads.
H10 report
The annual monitoring report Texas disposal and injection well operators file with the Railroad Commission, showing monthly injected volumes and pressures.
Injection pressure and MAOP
Injection pressure is how hard fluid is pushed into a well. MAOP is the maximum allowable operating pressure set in the well's permit, the highest pressure the operator is allowed to use.
Vapor recovery
Capturing the gas vapors that come off oil and water in a tank instead of venting or flaring them. Captured vapors can often be sold, and capture cuts emissions.
Vacuum truck haul
A trip by a vacuum truck that sucks fluid or sludge out of a tank and hauls it away. Each haul costs money, so fewer trips means lower operating cost.
Gun barrel tank
A tall settling tank, also called a wash tank, where oil and water are given time to separate by gravity. Oil rises to the top and water settles to the bottom.
Frac tank
A large portable steel tank on wheels used to hold water or other fluids temporarily, often during fracking, well work or tank cleanouts.
Emulsion
A mix of oil and water where tiny droplets of one are spread through the other, so they do not separate easily on their own. Heat, time or chemicals are often used to break it.
BS&W (basic sediment and water)
The water, sediment and other impurities mixed in with crude oil. Buyers measure it, and oil with too much BS&W can be rejected or discounted.
Bad oil
Oil that does not meet the buyer's quality specs, often because of too much water, sediment or emulsion. It usually needs treating before it can be sold.
Flash zone
The space at the top of a tank where light gases come out of the oil as pressure drops. Those vapors are richer in valuable hydrocarbons.
Static grounding
Connecting a tank or equipment to the earth so static electricity can drain away safely instead of building up and causing a spark.
InSAR ground motion
A satellite radar method that measures very small rises and drops in the ground surface over time. Regulators can use it to watch ground movement near disposal wells.