Natural Gas: Glossary

basin: or sedimentary basin, a concave-upward shaped geologic feature into which sediments are deposited in great thicknesses.

British Thermal Unit (BTU): is the amount of heat energy needed to raise the temperature of one pound of water by one degree F.

cement: new material precipitated around sediments buried below Earth's surface.

crude oil: see petroleum.

compressed natural gas (CNG): natural gas at pressures between 2900-3600 psi to reduce its volume to around 1% and used as a substitute for gasoline in motor vehicles

condensate: are a portion of natural gas that remain as gas under pressure in reservoirs, but transform to liquid phases (natural gas liquids) at surface pressure and temperature.

downstream: relates to oil and gas refining, marketing and distribution activities. (see also upstream.)

dry gas: natural gas that does not contain any condensates or one that has been treated to remove all liquids.

dry hole: a well that does not produce enough oil or gas to be economical.

faults: fractures in rocks along which displacement occurs.

folds: buckle-shaped structures in rocks formed by compression.

gas laws: scientific laws which describe how gases behave when their pressure, volume, or temperature changes. Charles's Gas Laws and Boyle's Law are two examples.

geophysics: branch of science that applies physical principles to study of planet Earth.

hydraulic fracturing: a method used to increase the flow of petroleum or gas from a reservoir by using pressurized fluids to artificially increase the permeability of the rocks.

hydrocarbons: family of organic compounds, composed entirely of carbon and hydrogen (for example, coal, crude oil and natural gas).

impermeable: Rocks where cracks and pore spaces are very small or are blocked by mineral growth. Fluids cannot flow through clays, cemented sandstone or salt.

liquefied natural gas (LNG): gas, mainly methane, liquefied under pressure and low temperature.

mercaptan: strong-smelling compounds of carbon, hydrogen and sulphur found naturally in oil and gas. They are added to natural gas for safety reasons to highlight leakages.

methanol: a simple alcohol produced from methane. Its uses range from antifreeze and solvents to an industrial ingredient (feedstock) in the manufacture of biodiesel and other compounds.

methane: CH₄, a naturally occurring gas composed of carbon and hydrogen, first member of paraffin series of hydrocarbons. Also a greenhouse gas.

mid-stream: the processing, storage, and transportation component of fossil fuel industry. It is commonly included in downstream processes.

natural gas: a gas consisting mainly of methane produced by the burial and heating of organic matter in sediment.

natural gas liquids: see condensates.

oil: mixture of liquid hydrocarbons of different molecular weights, also called crude oil.

permeable: rocks through which fluids can pass because of interconnected pores and fractures.

petroleum: generic name for hydrocarbons contained in sedimentary rocks, including crude oil, as well as natural gas and their products.

porous rocks: rocks that contain spaces between their grains or particles, e.g. sandstone.

seal or cap: rocks (salt, clays or cemented sandstone) in right shapes and relative positions to form traps.

sedimentary rock: rock formed by consolidation of deposits formed by settlement of sand, silt, and other materials.