1. adj. [Geology]
Pertaining to an oil field, an accumulation, pool or group of pools of oil in the subsurface. An oil field consists of a reservoir in a shape that will trap hydrocarbons and that is covered by an impermeable or sealing rock. Typically, industry professionals use the term with an implied assumption of economic size.
See: accumulation, field, hydrocarbon, oil pool, reservoir, seal, trap
2. adj. [Geology]
Pertaining to the surface area above a subsurface oil accumulation.
See: accumulation, field, hydrocarbon, oil field, oil pool, reservoir, seal