The rate at which a particle of ground is moving, i.e. a measure of ground vibration, in millimetres per second.

Pentolite is a high explosive used for military and civilian purposes e.g. warheads and booster charges.

Military pentolite comprises a mixture of 50% PETN and 50% TNT. A 50:50 mixture has a density of 1.65 g/cm3 and a detonation velocity of 7400 m/s. Civilian pentolite sometimes contains a lower percentage of PETN. Civilian pentolite has a detonation velocity of approximately 7,800 metres per second.

A perforating charge is a type of shaped charge used in the well industry to perforate casings and allow fluids to flow into the well.

A perforating charge is assembled from four components: case, main explosive pellet, primer, and liner.

When the explosives detonated the metal liner collapses into a high speed jet that perforated the well lining.

A perforation in the context of oil wells refers to a hole punched in the casing or liner of an oil well to connect it to the reservoir. In cased hole completions, the well will be drilled down past the section of the formation desired for production and will have casing or a liner run in separating the formation from the well bore. The final stage of the completion will involve running in perforating guns, a string of shaped charges, down to the desired depth and firing them to perforate the casing or liner. A typical perforating gun can carry many dozens of charges.

 Commonly, perforation guns are run on E-line as it is traditional to use electrical signals from the surface to fire the guns.

A perforation in the context of water, oil and gas wells refers to a hole punched in the casing or liner of an oil well to connect it to the reservoir. In cased hole completions, the well will be drilled down past the section of the formation desired for production and will have casing or a liner run in separating the formation from the well bore. The final stage of the completion will involve running in perforating guns, a string of shaped charges, down to the desired depth and firing them to perforate the casing or liner. A typical perforating gun can carry many dozens of charges.

Commonly, perforation guns are run on E-line as it is traditional to use electrical signals from the surface to fire the guns. In more highly deviated wells, coiled tubing may be used. Newer technologies allow the guns to be run on slickline. Modern slickline technology embeds fiber optic lines that can transmit two-way data on real-time temperature, pressure and seismic responses along the length of the slickline. This information allows very precise operations of various down hole tools, including perforation guns.

The benefit of this strategy is greater deal of control of the well. Casing the bottom of the hole allows the well to be completed without having to worry about reservoir fluids. It also allows precise selection of where in the formation production will be and to be able to seal off perforations, which are no longer useful or counterproductive, through cementing or straddling.

The disadvantage is that perforating can lead to "skin damage", where debris from the perforations can hinder productivity of the well. In order to mitigate this, perforating is commonly done underbalanced (lower pressure in the well bore than in the formation) as the higher well bore pressure will cause a surge of fluids into the well at the point of perforating, hopefully carrying the debris with it. Other methods of stimulation such as acidising and proppant fracturing are often required to overcome this damage and bring the well up to its full potential.

Casing and perforating as a method of completion is common place nowadays, though in some unconsolidated formations, prone to production of sand ( BP Harding as an example), open hole completions, using only sandscreens, may be the preferred choice.

Oil Well Perforation may be basically classified in two types a) Over-balanced Perforating and b) Under-balanced Perforating. Overbalanced perforating is normally carried out with the help of Perforating Guns or Hollow carriers. In Over -balanced Perforation the weight of the Well-bore Column is more than the Reservoir Pressure, thus it normally, ensures that the Well does not start flowing oil or Gas immediately after Perforation. However, it may have the effect of damaging the formation due to forced entry of well-bore fluid (mud) into the reservoir.

The techniques involving drill holes around or on the perimeter of an excavation, generally closely spaced, with the purpose of providing a predetermined face.

A decoupled packaged explosive often traced with detonating cord for presplit and smoothwall blasting in hole diameters between 32mm and 127mm diameter.

Items of clothing or devices worn to protect an individual from the actual or potential risks to health or safety arising from an activity or process.

PETN is a white powder and is one of the most powerful high explosives known, with a relative effectiveness factor of 1.66. In commercial explosives PETN is used as the base charge of detonators, the explosives core of most detonating cords and in cast Pentolite boosters.

PETN is impact sensitive.

 PETN mixed with a plasticizer forms a plastic explosive.

•  Pentaerithritrol a high explosive. Commonly used in detonating cord.
• Tetranitrate as the base charge in detonators.

A plain detonator consists of an open aluminium shell and a primary and base charge.

The primary charge is generally ASA, Lead Azide, Lead Styphnate and Aluminium a mixture very sensitive to F.I.S.H.

Plain detonators are crimped onto safety fuse to provide a delay detonator.

The presence of exposed primary explosives increase the risk of accidental initiation.