Oil and Gas Terms Beginning with “Z”

The Z/A effect in nuclear logging refers to the influence of the atomic number-to-mass ratio of formation elements on the photoelectric absorption factor (Pe) measured by the litho-density tool, where Pe quantifies the… Read more →

The Zoeppritz equations are a set of mathematical relationships derived in 1919 by German geophysicist Karl Zoeppritz that describe how seismic wave energy is partitioned at a boundary between two rock layers with… Read more →

The null point of a seismic trace. At zero deflection, the phase of a periodic signal is zero or pi. Read more →

Zero-zero gels describes a drilling fluid whose gel strength is so low that both the 10-second and the 10-minute readings measure at or very near zero when tested with a direct-indicating rotational viscometer according… Read more →

Zero-offset data is seismic data in which the energy source and the receiver occupy the same surface location, so the offset, meaning the horizontal separation between shot point and geophone, is zero. In this idealized… Read more →

A zero-offset vertical seismic profile, often abbreviated zero-offset VSP, is a borehole seismic survey in which the energy source is positioned at surface essentially directly above the downhole receivers, very close… Read more →

Zero-phase, in seismic data processing and interpretation, refers to a wavelet or seismic signal whose phase spectrum is zero at all frequencies, meaning the wavelet is perfectly symmetric about its central time sample… Read more →

Zero-zero gels describes a drilling fluid rheological condition in which both the 10-second and 10-minute gel strengths, measured on a Fann Model 35 six-speed rotational viscometer following API Recommended Practice… Read more →

Zinc basic carbonate (also written as zinc hydroxy carbonate or basic zinc carbonate, with the approximate formula Zn2(OH)2CO3 or more precisely Zn4CO3(OH)6H2O in the mineral form hydrozincite) is an inorganic compound… Read more →

Zinc bromide (ZnBr2) is an acidic inorganic salt used to prepare dense, clear (solids-free) brine completion and workover fluids — providing the highest density achievable from any single-salt water-based brine… Read more →

Zinc carbonate (ZnCO3) in oil and gas drilling operations is a chemical compound used as an H2S scavenger in drilling fluid formulations to neutralize hydrogen sulfide gas entering the wellbore from H2S-bearing… Read more →

Zinc chloride (ZnCl2) is a dense, water-soluble inorganic salt used in oilfield operations primarily as a completion and workover fluid component to achieve high-density, solids-free clear brines — zinc chloride… Read more →

A very weak base, ZnO, which can be used as a sulfide scavenger in oil-base or synthetic-base muds. Read more →

Zip collars are casing accessories that combine an integral stop collar and a centralizer body into a single unit that snaps directly onto the outside of casing pipe without welding, threading, or other pipe… Read more →

A slab of reservoirrock bounded above and below by impermeable rock. Read more →