| ECD |
abbreviation: equivalent circulating
density. |
| edgewater |
the water that touches the edge of the oil in
the lower horizon of a formation |
| effective
permeability |
a measure of the ability of a single fluid to
flow through a rock when another fluid is also present in the pore spaces. Compare absolute permeability, relative permeability. |
| effective
porosity |
the percentage of the bulk volume of a rock
sample that is composed of interconnected pore spaces that allow the passage of fluids
through the sample. See porosity. |
| eight-round |
a tapered connection with 8 threads per inch.
One turn equals 0.125 inches of travel. Very common oilfield connection. |
| elastomer |
an elastic material made of synthetic rubber
or plastic; often the main component of the packing material in blowout preventers and
downhole packers. |
| electric line |
see electric
well log |
| electric well log |
a record of certain electrical characteristics
(such as resistivity and conductivity) of formations traversed by the borehole. It
is made to identify the formations, determine the nature and amount of fluids they
contain, and estimate their depth. |
| electrolysis |
the decomposition of a chemical compound
brought about by the passage of an electrical current through the compound or through the
solution containing the compound. Corroding action of stray current is caused by
electrolysis |
| electrolyte |
1. a chemical that, when dissolved in water,
dissociates into positive and negative ions, thus increasing its electrical conductivity.
See dissociation. 2. the electrically conductive solution that must be present for a
corrosion cell to exist. |
| elevator bails |
see elevator
links |
| elevator links |
cylindrical bars that support the elevators
and attach them to the hook. Also called elevator
bails. |
| elevators |
clamps that grip a stand of casing, tubing,
drill pipe, or sucker rods so that the stand can be raised or lowered into the hole. |
| emulsified water |
water so thoroughly combined with oil that
special treating methods must be applied to separate it from the oil. Compare free water. |
| emulsifier |
see emulsifying
agent |
| 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. |
| emulsion |
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. |
| emulsoid |
colloidal particles that take up water. |
| endpoint |
the point marking the end of one stage of a
process. In filtrate analysis, the endpoint is the point at which a particular
result is achieved through titration. |
| entrained |
drawn in and transported by the flow of a
fluid. |
| entrained gas |
formation gas that enters the drilling fluid
in the annulus. |
| EP additive |
see extreme-pressure lubricant |
| 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. |
| equivalent circulating density (ECD) |
the increase in bottomhole
pressure expressed as an increase in pressure that occurs only when mud is being
circulated. Because of friction in the annulus as the mud is pumped, bottomhole
pressure is slightly, but significantly, higher than when the mud is not being pumped.
ECD is calculated by dividing the annular pressure loss by 0.052, dividing that by
true vertical depth, and adding the result to the mud weight. |
| 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. |
| ESD |
abbreviation: emergency
shut down, an automated platform system to shut in an SCSSV and/or SSV |
| ethane |
a paraffin hydrocarbon, C2H6; under
atmospheric conditions, a gas. One component of natural gas. |
| expansion
joint |
a device used to connect long
lines of pipe to allow the pipe joints to expand or contract as the temperature rises or
falls. |
| expendable
plug |
a temporary plug set of a PSA,
landed in a production packer to convert it to a bridge plug. |
| exploitation |
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. |
| exploration |
the search for reservoirs of oil and gas,
including aerial and geophysical surveys, geological studies, core testing, and drilling
of wildcats. |
| exploration well |
also called a wildcat. See wildcat. |
| 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. |
| extensions |
tubular components attached to the bottom of a
packer to extend it bore. |
| external cutter |
a fishing tool containing metal-cutting knives
that is lowered into the hole and over the outside of a length of pipe to cut it.
The severed part of the pipe can then be brought to the surface. |
| extreme-pressure
lubricant |
additives that, when added to drilling fluid,
lubricate bearing surfaces subjected to extreme pressure. |
