Shock barriers for explosives

A device for use in a wellbore, comprising:

• a detonating cord;
• an explosive proximal the detonating cord;
• and
• a shock barrier positioned between the detonating cord and the explosive to prevent pre-shock interference between the detonating cord and the explosive,
• wherein the shock barrier comprises a sleeve wrapped around at least a portion of the detonating cord proximal the explosive.

A device for use in a wellbore, comprising:

• a detonating cord;
• an explosive proximal the detonating cord;
• and
• a shock barrier positioned between the detonating cord and the explosive to prevent pre-shock interference between the detonating cord and the explosive,
• wherein the detonating cord comprises an outer jacket having a thickness, the thickness selected to provide the shock barrier.

A device for use in a wellbore, comprising:

• a detonating cord;
• an explosive proximal the detonating cord;
• a shock barrier positioned between the detonating cord and the explosive to prevent pre-shock interference between the detonating cord and the explosive;
• and
• a shaped charge containing the explosive, wherein the shock barrier is formed on an outer surface portion of the shaped charge, the shock barrier between the detonating cord and the outer surface portion of the shaped charge.

A device for use in a wellbore, comprising:

• a detonating cord;
• an explosive proximal the detonating cord;
• a shock barrier positioned between the detonating cord and the explosive to prevent pre-shock interference between the detonating cord and the explosive;
• and
• a shaped charge containing the explosive, wherein the shock barrier comprises a layer covering at least a back surface of the shaped charge.

A device for use in a wellbore, comprising:

• a detonating cord;
• an explosive proximal the detonating cord;
• a shock barrier positioned between the detonating cord and the explosive to prevent pre-shock interference between the detonating cord and the explosive;
• and
• a shaped charge containing the explosive, wherein the shaped charge comprises an outer case, and wherein the shock barrier is positioned between an inner wall of the outer case and the explosive.

A device for use in a wellbore, comprising:

• a detonating cord;
• an explosive proximal the detonating cord;
• and
• a shock barrier positioned between the detonating cord and the explosive to prevent pre-shock interference between the detonating cord and the explosive,
• wherein the shock barrier comprises a multi-layer barrier.

A method to protect a shaped charge of a perforating gun for use in a wellbore, comprising:

• providing a shock barrier between a detonating cord and an explosive in the shaped charge, wherein the providing comprises an act selected from the group consisting of:
• attaching the shock barrier to a rear surface of the shaped charge proximal the detonating cord;
• forming a sleeve around a portion of the detonating cord proximal the shaped charge;
• positioning a multi-layer shock barrier between the detonating cord and an explosive in the shaped charge;
• and
• positioning the shock barrier between the explosive and an inner wall of a shaped charge containing the explosive.

A perforating gun string for use in a wellbore, comprising:

• a plurality of shaped charges each comprising an explosive;
• at least one detonating cord coupled to the shaped charges;
• and
• a plurality of shock barriers positioned between the at least one detonating cord and respective ones of the shaped charges to reduce pre-shock interference between the detonating cord and the shaped charges.