Obtaining, by means of a gamma-ray probe, a record of the intensities of gamma rays emitted by the rock strata penetrated by a borehole.


Related Terms

POLISHING

1. In petroleum refining, removal of final traces of impurities, as for a lubricant, by clay adsorption or mild hydrogen treating. Smoothing and brightening a surface such as a metal or a rock through the use of abrasive materials.

PLASTER SHOOTING

A surface blasting method used when no rock drill is necessary or one is not available; consists of placing a charge of gelignite, primed with safety fuse and detonator, in close contact with the rock or boulder and covering it completely with stiff damp clay.

PLASMA TORCH

A torch in which temperatures as high as 50,000 C are achieved by injecting a plasma gas tangentially into an electric arc formed between electrodes in a chamber; the resulting vortex of hot gases emerges at very high speed through a hole in the negative electrode, to form a jet for welding, spraying of molten metal, and cutting of hard rock or hard metals.

PERCUSSION BIT

A rock-drilling tool with chisellike cutting edges, which when driven by impacts against a rock surface drills a hole by a chipping action.

PERCENTAGE LOG

A sample log in which the percentage of each type of rock (except obvious cavings) present in each sample of cuttings is estimated and plotted.

PENETRATION SPEED

The speed at which a drill can cut through rock or other material. penetration test

NONCORING BIT

A general type of bit made in many shapes which does not produce a core and with which all the rock cut in a borehole is ejected as sludge; used mostly for blasthole drilling and in the unmineralized zones in a borehole where a core sample is not wanted. Also known as borehole bit; plug bit.

MUDCAP

A quantity of wet mud, wet earth, or sand used to cover a charge of dynamite or other high explosive fired in contact with the surface of a rock in mud blasting.

MUCK

Rock or earth removed during excavation. mucking

MECHANOOPTICAL VIBROMETER

A vibrometer in which the motion given to a probe by a surface whose vibration amplitude is to be measured is used to rock a mirror; a light beam reflected from the mirror and focused onto a scale provides an indication of the vibration amplitude.

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