Abandon

To permanently plug and salvage equipment from a well. A well is ordinarily abandoned if it is a dry hole or has ceased to produce for some reason, which condition is believed permanent and beyond repair.

Acidize

To treat a well with acid, largely hydrochloric, to dissolve some limestone or other carbonate material in a producing zone. The object is to enlarge and reopen pores, vugs, and fractures in the zone to increase the flow of oil or gas into the well bore.

Aerate Hole to 650’

Using PVC instead of swabbing, pumping air down the backside of PVC. Similar to a gas lift.

Allowable

The amount of oil (or gas) which a well or lease is permitted to produce under proration orders of a State regulatory body. Some states, such as Texas, have a basic depth-bracket allowable schedule which varies with the depth of a well and the well spacing in acres per well. The allowable production for a particular month is then specified by the state as a percentage of the depth-bracket allowable.

Annulus

The space surrounding pipe suspended in the well bore. The outer wall of the annular space may be open hold or it may be a string of a larger pipe. In producing wells, the annular space is that between the tubing and the production string of casing.

Anticline

An elongated fold in rock strata in the form of a buried hill. This is a common type of oil and gas reservoir, with oil and gas being lighter, accumulating in the higher parts of the structure above water.

API Gravity

The density (weight per unit volume) of crude oil on a scale adopted by the American Petroleum Institute. On the API scale, the higher the gravity the lighter the oil. Most crude oils range from 27 degrees to 40 degrees API gravity; lower than that are termed heavy, lighter than that, light oils.

Aquifer

Water-bearing rock strata of large areal extent. In water drive fields, it is the water-occupied portion of the producing formation adjacent to or below the oil or gas-bearing part.

Artificial Lift

The application of power to mechanically or otherwise lift oil to the surface from a producing well.

Associated Gas

Gas occurring in or produced from a gas cap associated with an oil zone.

Attributable Acreage

Acreage attributed to a well or drilling unit for purposes of determining allowable where acreage enters into the allowable formula.