Z

Z-coordinate
The value of the z-axis in a 3 component coordinate system; e.g., lat-long-z; x-y-z.

Z-coordinate Domain
Z-coordinate dimensions, commonly depth or time.

Z-factor Value
The factor which compensates for the deviation of a gas from the ideal gas log when calculating pressure-temperature-volume relations.

Zero
The act of setting a dial indicating depth gauge for zero depth. Past tense is zeroed.

Zero Lag
The value of an auto correlation or cross correlation for zero time shift.

Zero Zero Gel
A condition wherein the drilling fluid fails to form measurable gels during a quiescent time interval (usually 10 min.).

Zeta Potential
Electrokinetic potential of a particle as determined by its electrophoretic mobility. This potential causes colloidal particles to repel each other and stay in suspension.

Zinc Chloride
(1) A very soluble salt used to increase the density of water to points more than double that of water. Normally added to a system first saturated with calcium chloride.(2) Will accelerate the thickening time of a cement slurry.

Zip Code
The U. S. Postal Service assigned code for a mail location.

Zone
An interval, layer or stratum to which are assigned interpretive attributes, transforming the interval into a zone of specific characteristics; e.g., pay zone; fossiliferous zone; porosity zone.

Zone Name
A word identifier assigned to an individually named producing or injection stratum within a multi-strata horizon.