Oil & Gas Terms in Category S

Sucker rod whip

An undesirable whipping motion in the sucker rod string that occurs when the string is not properly attached to the sucker rod pump or when the pump is operated at a resonant speed.



The area of the formation that is damaged because of the invasion of foreign substances into the exposed section of the formation adjacent to the wellbore during drilling and completion.


The pressure drop from the outer limits of drainage to the wellbore caused by the relatively thin veneer (or skin) of the affected formation.

Skin is expressed in dimensionless units: a positive value denotes formation damage; a negative value indicate improvement.

Also called skin effect.


A dimensionless estimation of obstruction to flow.

An undamaged well would have a skin of zero.

A damaged well has a positive skin above zero and a stimulated well has a negative skin.

Shr (subsea)


Subsea hybrid riser.

Shear ram preventer

A blowout preventer that uses shear rams as closing elements.


Wedge-shaped toothed pieces of metal that fit inside a bowl and are used to support tubing or other pipe.


Action or stress that results from applied forces and that causes or tends to cause two adjoining portions of a substance or body to slide relative to each other in a direction parallel to their plane of contact.


A complex carbohydrate sometimes added to drilling fluids to reduce filtration loss.

Storage gas

Gas that is stored in an underground reservoir.

Suction tank

The mud tank from which mud is picked up by the suction of the mud pumps.

Also called a suction pit.


A substance that is dissolved in another (the solvent).


A sedimentary rock composed of individual mineral grains of rock fragments between 1/16 and 2 millimeters in diameter and cemented together by silica, calcite, iron oxide, and so forth.

Sandstone is commonly porous and permeable and therefore a likely type of rock in which to find a petroleum reservoir.


See semisubmersible drilling rig.

Sample mud

Drilling fluid formulated so that it will not alter the properties of the cuttings the fluid carries up the well.


Abbreviation: shut-in drill pipe pressure, used in drilling reports.

Selective shear

The ability to determine selectively, by the quantity of shear screws or pins, when a tool will set