Oil & Gas Terms in Category S

Spud in

To begin drilling; to start the hole.

Sour corrosion

Embrittlement and subsequent wearing away of metal caused by contact of the metal with hydrogen sulfide.

Sand screen

A screen joint placed opposite perforations in sand control

Sodium chloride

Common table salt.

It is sometimes used in cement slurries as an accelerator or a retarder, depending on the concentration.



The well cuttings obtained at designated footage intervals during drilling.

From an examination of these cuttings, the geologist determines the type of rock and formations being drilled and estimates oil and gas content.


Small quantities of well fluids obtained for analysis.



Stock tank barrel.

Screen liner

A pipe that is perforated and often arranged with a wire wrapping to act as a sieve to prevent or minimize the entry of sand particles into the wellbore.

Also called a screen pipe.


A device placed at the end of or beneath an object for various purposes (e.g., casing shoe guide shoe).

Shaker tank

The mud tank adjacent to the shake shaker, usually the first tank in to which mud flows after returning from the hole.

Also called a shaker pit.

Sand content

The insoluble abrasive solids content of a drilling fluid rejected by a 200-mesh screen.

Usually expressed as the percentage bulk volume of sand in a drilling fluid.

This test is an elementary type in that the retained solids are not necessarily silica and may not be altogether abrasive.

For additional information concerning the kids of solids retained on the 200-mesh screen, more specific tests would be required.

See mesh.

Sidewall coring

A coring technique in which core samples are obtained from the hole wall in a zone that has already been drilled.

A hollow bullet is fired into the formation wall to capture the core and then retrieved on a flexible steel cable.

Core samples of this type usually range from 3/4 to 1-3/16 inches (20 to 30 millimeters) in diameter and from 3/4 to 4 inches (20 to 100 millimeters) in length.

This method is especially useful in soft-rock areas.

String shot

An explosive method utilizing primacord, which is an instantaneous textile-covered fuse with a core of very high explosive.

It is used to create an explosive jar inside st5uck drill pipe or tubing so that the pipe may be backed off at the joint immediately above where it is stuck.

Space out

The act of ensuring that a pipe ram preventer will not close on a drill pipe tool joint when the drill stem is stationary.

A pup joint is made up in the drill string to lengthen it sufficiently.

Slack off

To lower a load or ease up on a line.

Sodium bicarbonate

The half-neutralized sodium salt of carbonic acid, used extensively for treating cement contamination and occasionally other calcium contamination in drilling fluids.