ABSTRACT
This chapter examines the penetration depth as a function of rock properties and stress environment. Shaped charges represent a special case of hyper-velocity penetration in rocks and soils. They are commonly used to perforate well casings in the petroleum industry and are also in less frequent use in the mining industry. While military shaped charges typically use solid metal liners, oil-well perforators are made with pressed metal powders. This results in a lower-density jet composed of loose particles with virtually no strength at all, and avoids possible plugging of the perforation with metal. Penetration of shaped charges in rock samples is reduced by application of confining stress, but to a lesser degree than predicted by increased rock compressive strength. Pressure-induced increases in acoustic velocity mirror penetration decreases but require scaling by a factor that depends strongly on the rock type.
