What makes a big hole charge big and a deep penetrating charge deep?
In terms of specifications a shaped charge is classified as a big hole when it creates an entrance hole (EH) in excess of 0.55″ and a super big hole (SBH) is any shaped charge that creates a EH in excess of 0.80″. The deep penetrating charge category consists of any charge that creates a deep perforation tunnel. This value is charge specific. What makes a big hole charge a big hole charge and not a deep penetrator is in the science of the liner and its design. In general a big hole liner is shaped like a shallow dish and a deep penetrator is more like a cone. This change in shape allows for a variation in focus point of the jet stream when the charged is detonated. The shallow focus point of the big hole allows for a broader, fuller jet stream to develop which in turn creates a big hole in the casing and into the formation. However this larger jet stream tends to loose energy rapidly. Therefore it may not penetrate the formation beyond ~12″. A big hole charge is mainly used in regions
