A pool of petroleum locally confined by subsurface geologic features.

Often referred to as AMD, refers to the outflow of acidic water from (usually abandoned) metal mines or coal mines.

The highest rank of coal. It is a hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter.

American Petroleum Institute (API) gravity is a measure of how heavy or light a petroleum liquid is compared to water. If its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks. It is used to compare the relative densities of petroleum liquids.

An aquifer is a formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs.

An assessment unit is a volume of rock within the Total Petroleum System that encompasses fields, discovered and undiscovered, sufficiently homogeneous in terms of geology, exploration strategy and risk characteristics to constitute a single population of field characteristics with respect to criteria used for resource assessment.

A generic term applied to natural inflammable substances of variable color, hardness, and volatility, composed principally of a mixture of hydrocarbons substantially free from oxygenated bodies.

Middle rank coal (between subbituminous and anthracite) formed by additional pressure and heat on lignite. Usually has a high Btu value and may be referred to as "soft coal."

A breccia pipe is a mass of breccia (a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix) often in an irregular and cylindrical shape. They usually consist of fragments of the host rock (the rock layer they are contained in) cemented together by silica. These formations are often hosts for ore depositi [..]

(British thermal unit) - The amount of heat needed to raise the temperature of 1 pound of water by 1 degree fahrenheit. The Btu is a convenient measure by which to compare the energy content of various fuels.