Coring describes the process of taking rock samples from a well by means of a special tool called a core barrel. The core barrel itself may be thought of as a special storage chamber for holding the rock core. The core catcher serves to grip the bottom of the core and, as tension is applied to the drillstring, the rock under the core breaks away from the undrilled formation below it.

This is a general term for unrefined petroleum or liquid petroleum

A standard unit used to measure the quantity of gas (at atmospheric pressure); 1 cubic foot = 0.0283 cubic meters.

Rock chips cut from the formation by the drill bit, and brought to the surface with the mud. Used by geologists to obtain formation data.

The tower-like structure that houses most of the drilling controls. They are usually pyramidal in shape and offer a good strength-to-weight ratio. If the derrick design does not allow it to be moved easily in one piece, special ironworkers must assemble them piece by piece, and in some cases disassemble them if they are to be moved.

The phase of petroleum operations that occurs after exploration has proven successful, and before full-scale production. 

A well drilled in a proven field for the purpose of completing the desired spacing pattern of production.

The tool used to crush or cut rock. The bit is on the bottom of the drillstring and must be changed when it becomes excessively dull or stops making progress. Most bits work by scraping or crushing the rock, or both, usually as part of a rotational motion.

A drilling unit that is not permanently fixed to the seabed.

The drillpipe connects the rig surface equipment with the bottomhole assembly and the bit, both to pump drilling fluid to the bit and to be able to raise, lower and rotate the bottomhole assembly and bit.

A drip is a small vessel in a pipeline which receives water and heavy hydrocarbons that drop out of a gas stream. Drips are normally installed in the lower points of flow lines and must be blown periodically to remove liquids.

Dry gas is natural gas that is composed mainly of methane with only minor amounts of ethane, propane and butane and little or no heavier hydrocarbons in the gasoline range. 

An oil recovery enhancement method using sophisticated techniques that alter the original properties of oil. Refers to a variety of processes to increase the amount of oil removed from a reservoir, typically by injecting a liquid (e.g., water, surfactant) or gas (e.g., nitrogen, carbon dioxide).

Drilling carried out to determine whether hydrocarbons are present in a particular area or structure.

Drilling carried out to determine whether hydrocarbons are present in a particular area or structure. Also known as a ‘wildcat well’.