Oil & Gas Terms in Category F

Fracture pad

The initial part of the fracture fluid that creates the fracture width and controls the initial fluid loss but contains no proppant.

Flash set

A premature thickening or setting of cement slurry, which makes it unpumpable.

Flocculating agent

Material or chemical agent that enhances flocculation.

Flow test

Preliminary test to confirm flow rate through a tool prior to going downhole.

Fusible plugs

A thermal device employed on surface flow lines as part of an emergency shutdown.

Flow chart

A chart made by a recording meter which shows rate of production.

Formation fracturing

A method of stimulating production by opening new flow channels in the rock surrounding a production well.

Often call a frac job.

Under extremely high hydraulic pressure, a fluid (such as distillate, diesel fuel, crude oil, dilute hydrochloric acid, water, or kerosene) is pumped downward through production tubing or drill pipe and forced out below a packer or between two packers.

The pressure causes cracks to open in the formation, and the fluid penetrates the formation through the cracks.

Sand grains, aluminum pellets, walnut shells, or similar materials (propping agents) are carried in suspension by the fluid into the cracks.

When the pressure is released at the surface, the fracturing fluid returns to the well.

The cracks partially close on the pellets, leaving channels for oil to flow around them to the well.

See explosive fracturing, hydraulic fracturing.

Free water


Water produced with oil.

It usually settles out within five minutes when the well fluids become stationary in a settling space within a vessel.


The measured volume of water that is present in a container and that is not in suspension in the contained liquid at observed temperature.

Flat gel

A condition wherein the 10-minute gel strength is substantially equal to the initial gel strength.

Filtration rate

See fluid loss.


A section of drill pipe, casing, or tubing consisting of four joints screwed together.

Compare double, single, thribble.

Fluid pressure gradient

A measurement in the well of the pressure vs.


Useful for spotting liquid levels, leaks, fluid entries, etc.

Formation integrity

See formation competency.

Free-point indicator

A device run on wireline into the wellbore and inside the fishing string and fish to locate the area where a fish is stuck.

When the drill string is pulled and turned, the electromagnetic fields of free pipe and stuck pipe differ.

The free-point indicator is able to distinguish these differences, which are registered on a metering device at the surface.

Fluid saturation

The amount of the pore volume of a reservoir rock that is filled by water, oil, or gas and measured in routine core analysis.