Oil & Gas Glossary 1.0

The amount of heat required to cause a unit increase in temperature in a unit mass of a substance, expressed as numerically equal to the number of calories needed to raise the temperature of 1 gram of a substance by 1 degree C.

A hypothetical temperature at which there is a total absence of heat. Since heat is a result of energy caused by molecular motion, there is no motion of molecules with respect to each other at absolute zero.

A measure of the resistance of a fluid to flow. Resistance is brought about by the internal friction resulting from the combined effects of cohesion and adhesion. The viscosity of petroleum products is commonly expressed in terms of the time required for a specific volume of the liquid to flow through a capillary tube of a specific size at a given temperature.

1. the ability to transmit or convey (as heat or electricity).

A vessel in which oil is treated for the removal of S&W or other objectionable substances by the addition of chemicals, heat, electricity, or all three.

To loosen a collar or other threaded connection by striking it with a hammer.

See relative density

A device for measuring and recording the specific gravity of a gas or liquid passing a point of measurement.

Resistance to movement created when two surfaces are in contact. When friction is present, movement between the surfaces produces heat.

Lead sulfide (PbS). Technical grades (specific gravity about 7) are used for increasing the density of drilling fluids to points impractical or impossible with barite.

1. for ships, water taken onboard into specific tanks to permit proper angle of repose of the vessel in the water, and to assure structural stability.

A device used to measure the depth of a well or the depth at a specific point in a well (such as to the top of a liner or to a fish) by counting the turns of a calibrated wheel rolling on a wireline as it is lowered into or pulled out of the well.

2. of aggregates, subdivision of aggregates. Dispersion increases the specific surface of the particle; hence, it results in an increase in viscosity and gel strength.

A minute unit of matter, usually a single crystal, or of regular shape with a specific gravity approximately that of a single crystal

A secondary-cementing operation in which a plug of cement is positioned at a specific point in the well and allowed to set.

The specific gravity or density of oil expressed in terms of a scale devised by the American Petroleum Institute. The lighter the oil, the greater the gravity; other factors being equal, the higher the API gravity, the better price the oil will bring.

A substance that consists of large molecules formed from smaller molecules in repeating structural units (monomers). In oilfield operations, various types of polymers are used to thicken drilling mud, fracturing fluid, acid, water, and other liquids. See micellar-polymer flooding, polymer mud. In petroleum refining, heat and pressure are used to polymerize light hydrocarbons into larger molecules, such as those that make up high-octane gasoline. In petrochemical production, polymer hydrocarbons are used as a feedstock for plastics.

To pump a designated quantity of a substance (such as acid or cement) into a specific interval in the well. For example, 10 barrels of diesel oil may be spotted around an area in the hole in which drill collars are stuck against the wall of the hole in an effort to free the collars.

An installation designed for one or more specific and limited extraction units, scrubbers, absorbers, drip points, conventional single or multiple stage separation units, LTX low temperature separators, and other types of separation and recovery equipment.

A method of improved recovery in which steam is injected into a reservoir through injection wells and driven toward production wells. The steam reduces the viscosity of crude off, causing it to flow more freely. The heat vaporizes lighter hydrocarbons; as they move ahead of the steam, they cool and condense into liquids that dissolve and displace crude oil The steam provides additional gas drive. This method is used to recover viscous oils. Also called continuous steam injection or steam flooding.

The mass or weight of a substance per unit volume. For instance, the density of a drilling mud may be 10 pounds per gallon (ppg), 74.8 pounds per cubic foot (lb/ft), or 1,198.2 kilograms per cubic meter (kg/m3). Specific gravity, relative density, and API gravity are other units of density.

Any cementing operation after the primary cementing operation. Secondary cementing includes a plug-back job, in which a plug of cement is positioned at a specific point in the well and allowed to set. Wells are plugged to shut off bottom water or to reduce the depth of the well for other reasons.

The large wrenches used to make up or break out drill pipe, casing, tubing, or other pipe; variously called casing tongs, pipe tongs, and so forth, according to the specific use. Power tongs are pneumatically or hydraulically operated tools that serve to spin the pipe up tight and, in some instances, to apply the final makeup torque.

Density expressed as the ratio of the weight of a volume of substance to the weight of an equal volume of another standard substance. In the case of liquids and solids, the standard is water. In the case of natural gas or other gas materials, the standard is air.

A mechanical fluid-measuring device that measures by filling and emptying chambers of a specific volume. The displacement of a fixed volume of fluid may be accomplished by the action of reciprocating or oscillating pistons, rotating vanes or buckets, rotating disks, or tanks or other vessels that automatically fill and empty. Also called a volume meter or volumeter.

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.

A test that measures the reservoir pressure of the well, obtained at a specific depth or at the midpoint of the producing zone. A flowing bottomhole pressure test measures pressure while the well continues to flow; a shut-in bottomhole pressure test measures pressure after the well has been shut in for a specified period of time. See bottomhole pressure, bottomhole pressure gauge.