Target Energy - Australian petroleum exploration and production company.

GAS CAP
Free gas, separate from, but overlying an oil zone that occurs within the same producing formation as oil. Since gas is lighter, it occupies the upper part of the reservoir.

GAS KICK
Increase of down hole pressure above that exerted by the column of drilling fluid in a well, allowing gas to escape to the surface. If not controlled this could develop into a blowout.

GAS/OIL RATIO (GOR)
The proportional amount of gas to oil liquid occurring in production from a reservoir, usually expressed as cubic feet per barrel.


HORIZON
Distinct layer or group of layers of rock.

HYDROCARBONS
Organic chemical compounds of hydrogen and carbon whose densities, boiling points, and freezing points increase as their molecular weights increase. The molecular structure of the most common petroleum hydrocarbon compounds varies from the simplest - methane, a constituent of natural gas - to the very heavy and complex.


IMPERMEABLE ROCK
A rock with restricted or poorly-communicating pore spaces, such that hydrocarbons will not flow through it.

INFILL DRILLING
Drilling of wells according to a planned pattern and spacing to achieve full production from a new field.

IN PLACE
Description of the total hydrocarbon content of a reservoir, as distinct from 'Reserves' which can be 'recovered' or produced. Oil or gas in place (OIP, GIP) before the start of production is known as Oil or Gas Originally in Place or Initially in Place. (e.g. STOOIP = Stock Tank Oil Originally in Place; GIIP = Gas Initially in Place).


JARS
Down hole tools inserted in the drill-string when fishing to jerk or jar the fish free by repeated sudden blows. They may also be used while drilling to avoid the drill-string becoming stuck.

JOINT
A single length of pipe. Coupled or welded to other lengths, joints become a string. The term joint may also refer to the couplings or joints themselves.

JUNK
Any unwanted object 'lost' down a well.