Prospecting and exploration notes

Radiometric, magnetic, seismic, gravity, induced polarization, resistivity

Geophysics

Magnetic survey

detects location of large igneous masses, magnetite ilmenite series,magnetite associated with gold placers, pyrrhotite, magnetite chalcopyrite,magnetic nickel ores

Gravity survey

Detection of faults, intrusions,burried channels, ores detected are chromite,hematite,barrite that have such high density compared with the material that surrounds them.

Resistivity

measures resistance to current flow of geologic materials.

Massive sulfide bodies such as aresenopyrite, chalcopyrite, quartz veins, cavities in limestone.

Radiometric Survey

Common equipment used is the Gieger counter for detecting radiation emitted by radioactive minerals (alpha and beta radiation).

For uranium, thorium deposits.

Induced polarization

Usually detects dessiminated sulfides.

Seismic methods

Usually done by detonating a charge of explosives and measuring the reflection and refraction of artificial earthquake waves set up by shock.

Mostly used in petroleum industry.

Rotary drilling

is used for overburden penetration, then substituted with diamond drill for coring.

A none coring method and is unequalled for drilling though soft to medium hard rocks such as limestone,chalk or mudstone.

Produces cuttings.

Diamond drilling

a type of rotary drag drilling

uses a drill bit with diamonds (impregnated or surface set), for stronger penetration.

Produces drill cores

Percussion drilling

is used for shallow, medium to hard penetration wthout coring.

a hammer unit driven by compressed air impacts a series of short rapid blows to the drill rods or bit and at the same time imparts a rotary motion.

Produces cuttings.

Barite and bentonite

example of drilling mud

Barite

is denser and used primarily as a weighting agent in drilling fluids.

Bentonite

is less dense and used for its swelling properties, lubricating and stabilizing abilities in drilling muds and other industrial applications.

Polygon method, triangle method, section method

Reserve estimation method

Polygon method

areas of influence are assigned to each hole, influence extends halfway to the next adjacent.

Triangle Method

drill holes are the apices of the triangles. This is more advantageous since computation of tonnage includes 3 drillholes.

Acheson process

A process for the production of artificial or synthetic graphite.

Auger drilling

A way to obtain oils samples from different depths by drilling without having to dig a pit.