Oil & Gas Terms in Category T

Tree saver tool

A tubular device employed as an isolation tool inside the christmas tree, to increase the tree’s pressure rating during stimulation.

Top off

To fill a wellbore up to the surface.

Ten-minute gel strength

The measured 10-min gel strength of a fluid is the maximum reading (deflection) taken from a direct-reading viscometer after the fluid has been quiescent for 10 minutes.

The reading is reported in lb/100 sq.


See api rp 13b for details of test procedure.

Test pressure

An equipment’s working pressure times a safety factor.

Tensile strength

The greatest longitudinal stress that a metal can bear without tearing apart.

A metal’s tensile strength is greater than its yield strength.

Temperature survey

An operation used to determine temperatures at various depths in the wellbore.

It is also used to determine the height of cement behind the casing and to locate the source of water influx into the wellbore.

Thief zone

See thief formation


A stand of pipe made up or three joints and handled as a unit.

Compare double, fourable, and single.


Abbreviation: through-the-flow-line.

Test well

A wildcat well.


Terminology used to describe a screen that, when packed off by gels, will give a pressure rise at the surface, thereby “telling” the tool operator that the gel has reached a certain location.

Also called tattle-tale.

Thread protector.

A metal or plastic device that is screwed onto or into pipe threads to protect 5them from damage when the pipe is not in use.

Thermal decomposition

The breakdown of a compound or substance by temperature into simple substances or into constituent elements.


The property exhibited by a fluid that is in a liquid state when flowing and in a semisolid, gelled state when at rest.

Most drilling fluids must be thixotropic so that cuttings will remain in suspension when circulation is stopped.

Ten round

Same as an eight round, except ten threads per inch.