Lexicon of Terms

Learn how to talk like an Oilman
417 Oil & Gas and related investment terms defined.
Arab oil embargo of 1973-74 — During the Arab-Israeli conflict in October 1973, Arab oil producers cut off shipments to the Unites States and the Netherlands in retaliation for their support of Israel. At the same time, they cut down production. The shortage was felt by all oil-importing nations, with world prices moving sharply higher. Price and allocation controls suppressed some of this increase in the United States, but gasoline lines were still prevalent.

Acre-foot — In the U.S., the thickness of a pay zone is measured in feet, and the area of the reservoir is measured in acres. An acre-foot is a volume of reservoir rock that is one acre in area and one foot thick.

API gravity — The gravity (weight per unit of volume) of crude oil expressed in degrees according to an American Petroleum Institute recommended system. The higher the API gravity, the higher the crude. High-gravity crudes are generally considered more valuable.

Annulus of a well — The space between the surface casing and the inner, producing well-bore casing.

AFE (Authorization For Expenditure) — An estimate of the costs of drilling and completing a proposed well, which the operator provides to each working interest owner before the well is commenced.

Anticline — A geological term describing a fold in the earth's surface with strata sloping downward on both sides from a common crest. Anticlines frequently have surface manifestations like hills, knobs, and ridges. At least 80 percent of the world's oil and gas has been found in anticlines.

Associate gas — The gas that occurs with oil either as free gas or in solution. When occurring alone, it is referred to as unassociated gas.

Asphalt — A solid hydrocarbon which may be deposited within the reservoir rock, in well equipment, or in surface lines and tanks.

Annular space — The space between a well's casing and the wall of the borehole.

API — American Petroleum Institute, a petroleum industry association that sets standards for oil field equipment and operations.

Aquifer — An underground water reservoir contained between layers of rock, sand or gravel.


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