Oil & Gas Terms in Category R


A substance added to cement to prolong the setting time so that the cement can be pumped into place.

Retarders are used for cementing in high-temperature formation

Remote control station

A station containing equipment to control and regulate operations in the field.

Ring-joint flange

A special type of flanged connection in which a metal ring (resting in a groove in he flange) serves as a pressure seal between the two flanges.


The process whereby a volume of fluid equal to the volume of steel in tubular and tools withdrawn from the wellbore is returned to the wellbore.

Riser pipe

The pipe and special fittings used on floating offshore drilling rigs to establish a seal between the top of the wellbore, which is on the ocean floor, and the drilling equipment, located above the surface of the water.

A riser pipe serves as a guide for the drill stem from the drilling vessel to the wellhead and as a conductor of drilling fluid from the well to the vessel.

The riser consists of several sections of pipe and includes special devices to compensate for any movement of the drilling rig caused by waves.

It is also called a marine riser.


A cast-iron or magnesium drillable tool consisting of a packing assembly and a back-pressure valve.

It is used to close off the annular space between tubing or drill pipe and casing to allow the placement of cement or fluid through the tubing or drill pipe at any predetermined point behind the casing or liner, around the shoe, or into the open hole around the shoe.

Riser margin

The slight increase in mud weight needed to offset the loss in hydrostatic pressure when the riser is disconnected from the ss bope and the hydrostatic pressure of the mud from rkb to the mud line is replaced by the hydrostatic pressure of weight of the column of sea water from sea level to the mud line.

Radioactivity well logging

The recording of the natural or induced radioactive characteristics of subsurface formations.

A radioactivity log, also known as a radiation log or a nuclear log, normally consists of two recorded curves: a gamma ray curve and a neutron curve.

Both help to determine the types of rocks in the formation and the types of fluids contained in the rocks.

Round trip

The action of pull out and subsequently running back into the hole a string of drill pipe or tubing.

Making a round trip is also called tripping.

Recovery efficiency

The recoverable amount of original or residual hydrocarbons in place in a rese4rvoir, expressed as a percentage of total hydrocarbons in place.

Also called recovery factor.


A device that reduces the pressure or volume of a fluid flowing in a line and maintains the pressure or volume at a specified level.


Semisolid or solid complex, amorphous mixture of organic compounds having no definite melting point or tendency to crystallize.

Resins may be a component of compounded materials that can be added to drilling fluids to impart special properties to the system, to wall cake, etc.


Fracturing a formation again.

See formation fracturing, hydraulic fracturing.


The study of the flow of gases and liquids of special importance to mud engineers and reservoir engineers.

Rod pump

See sucker rod pump