The last casing set in a well though which oil and gas are extracted.

A petroleum- or water-bearing formation of relatively low porosity and permeability.

Abandon

A well stimulation technique used to increase the flow of oil and gas from a well.

The space around a pipe in a well bore, sometimes termed the annular space.

American Petroleum Institute. API is a national trade association that represents all aspects of the oil and natural gas industry. API develops industry standards, conducts and sponsors research, and organizes seminars, workshops, conferences and symposia on public policy issues. http://www.api.org

A unique number assigned to each well in the United States. An API Number is comprised of four parts: state code, county code, well code and wellbore code. An optional extension code may be attached.

The lowest or deepest part of a well.

A unit of measure for oil and petroleum products that is equivalent to 42 U.S. gallons.

A measure of the heating value of a fuel.