Oil & Gas Terms in Category E

Epm or equivalents per million

Unit chemical weight of solute per million unit weights of solution.

The epm of a solute in solution is equal to the ppm (parts per million) divided by the equivalent weight.


Expected ultimate recovery from a field.


Abbreviation: emergency shut down, an automated platform system to shut in an scssv and/or ssv

Enhanced oil recovery

One or more of a variety of processes that seek to improve recovery of hydrocarbon from a reservoir after the primary production phase.

Emulsifying agent

A material that causes water and oil to form an emulsion.

Water normally occurs separately from oil; if, however, an emulsifying agent is present, the water becomes dispersed in the oil as tiny droplets.

Or, rarely, the oil may be dispersed in the water.

In either case, the emulsion must be treated to separate the water and the oil.


The development of a reservoir to extract its oil.

Exploitation well

A well drilled to permit more effective extraction of oil from a reservoir.

Sometimes called a development well.

See development well.


Colloidal particles that take up water.

Explosive fracturing

When explosives are used to fracture a formation.

At the moment of detonation, the explosion furnishes a source of high-pressure gas to force fluid into the formation.

The rubble prevent fracture healing, making the use of proppants unnecessary.

Compare hydraulic fracturing.

Equivalent weight or combining weight

The atomic or formula weight of an element, compound, or ion divided by its valence.

Elements entering into combination always do so in quantities proportional to their equivalent weights.


Tubular components attached to the bottom of a packer to extend it bore.

Elevator links

Cylindrical bars that support the elevators and attach them to the hook.

Also called elevator bails.

Elevator bails

See elevator links

Extreme-pressure lubricant

Additives that, when added to drilling fluid, lubricate bearing surfaces subjected to extreme pressure.


A mixture in which one liquid, termed the dispersed phase, is uniformly distributed (usually as minute globules) in another liquid, called the continuous phase or dispersion medium.

In an oil-water emulsion, the oil is the dispersed phase and the water the dispersion medium; in a water-oil emulsion, the reverse holds.

A typical product of oilwells, water-oil emulsion is also used as a drilling fluid.