Page 499 - Practical Well Planning and Drilling Manual

Appendix NEW! revised 11/00/bc 1/30/01 3:30 PM Page 475

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Glossary

Equivalent Circulating Density. For a circulating fluid, the equiva-
lent circulating density in lb/gal equals the hydrostatic head (psi)
plus the total annular pressure drop (psi) divided by the depth (ft)
and by 0.052.

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 pro-
portional to their equivalent weights.

Eutectic Point. When increasing the concentration of salt in a brine,
the temperature at which crystals come out of solution at first lowers.
At a certain point, addition of more salt will cause this crystallization
point temperature to increase. This point, the lowest temperature at
which a brine will precipitate salt crystals, is called the eutectic point.

Fast Line. The end of the drilling line which is fixed to the draw-
works drum or reel. It is so called because it apparently travels with
greater velocity than any other portion of the drilling line.

Fault. Geological term denoting a formation break, upward or down-
ward, in the subsurface strata. Faults can significantly affect the area
mud and casing programs.

Feed-Off. The act of unwinding a cable from a drum. Also a device
on a drilling rig that keeps the weight on the bit constant and lowers
the drilling line automatically. See also Automatic Driller.

Feet per hour (fph). Used to express rate of drilling penetration.

Feet per minute (fpm). Velocity, e.g., of flow in the annulus or pipe
movement.

Feet per second (fps). Velocity, e.g., of flow from the bit nozzles.

Fiber Or Fibrous Materials. Any tough stringy material used to pre-
vent loss of circulation or to restore circulation. In field use, fiber
generally refers to the larger fibers of plant origin.

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