Oil and Gas Terms Beginning with “U” — Page 2

To initiate flow from a reservoir by removing the column of kill fluid from the wellbore. Several methods of unloading the well are used, including circulation of lower density fluid, nitrogen lifting and swabbing. The… Read more →

A system that is in a transient state at the time of a measurement. In the case of permeability measurements on core samples, two transient techniques are used. In the pressure falloff method, the sample is at… Read more →

A mud that contains no commercial weighting material. Native-solids muds are unweighted muds, containing no barite. More solids-control techniques are available for unweighted muds than for weighted muds. In fact,… Read more →

Located up the slope of a dipping plane or surface. In a dipping (not flat-lying) hydrocarbon reservoir that contains gas, oil and water, the gas is updip, the gas-oil contact is downdip from the gas, and the oil-water… Read more →

A refinery unit used to improve or upgrade heavy oil to produce higher-quality hydrocarbon liquids or upgraded synthetic crudes. The refining unit may include any combination of the following: hydrogen addition… Read more →

A part at the end of tubulars, such as drillpipe, casing or other tubing, which has extra thickness and strength to compensate for the loss of metal in the threaded ends. Read more →

Pertaining to equipment, facilities or systems located in the wellbore or production train above the surface choke or Christmas tree. Read more →

The stage of downhole pumping at which the polished rod is going up and the downhole pump is pumping fluid. Read more →

The use of measurements of a field at one elevation, level or surface to determine the values of the field at a higher level. The technique is most often used on potential fields, such as gravity or magnetic fields, to… Read more →

An element with an atomic number of 92. The 238U isotope is radioactive and decays with a half-life of 4.4 * 109 years through a series of intermediate isotopes to a stable isotope of lead. The intermediate isotopes… Read more →