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By using reactive shaped charges, a dynamic underbalance effect associated with detonation of a perforating system is enhanced without compromising shot density. Fewer shaped charges can be loaded to achieve the same or better effective shot density as a gun fully loaded with conventional shaped cha

By using reactive shaped charges, a dynamic underbalance effect associated with detonation of a perforating system is enhanced without compromising shot density. Fewer shaped charges can be loaded to achieve the same or better effective shot density as a gun fully loaded with conventional shaped charges, thereby increasing the free volume within the gun while creating debris-free tunnels with fractured tips and substantially eliminating the crushed zone surrounding each perforated tunnel. Further, the strength and grade of gun steel required to construct the gun can be reduced without compromising the amount the gun swells following detonation.

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1. A method for perforating a wellbore adjacent to an underground hydrocarbon bearing formation by using reactive shaped charges, the wellbore and formation being such that a maximum pressure gradient achievable between the formation and the wellbore, with minimum achievable hydrostatic pressure in

1. A method for perforating a wellbore adjacent to an underground hydrocarbon bearing formation by using reactive shaped charges, the wellbore and formation being such that a maximum pressure gradient achievable between the formation and the wellbore, with minimum achievable hydrostatic pressure in the wellbore, is insufficient to create a cleaning surge flow when using conventional charges for creating perforated tunnels, the method including creating a dynamic underbalance around a charge carrier as a result of detonation of the reactive shaped charges, the dynamic underbalance of sufficient magnitude to create a cleaning surge flow, the method comprising the steps of: a) providing a charge carrier having a substantially empty internal volume and comprising a plurality of cavities for receiving charges;b) filling selective cavities of the charge carrier with charges comprising the reactive shaped charges having a liner component, the number of cavities filled being fewer than the total number of cavities, the number of filled cavities selected on enhancing the dynamic underbalance upon detonation to cause the cleaning surge flow of explosion debris from the formation to the charge holder;c) sealing the cavities of the charge carrier to maintain pressure inside the charge carrier;d) positioning the selectively filled and sealed charge carrier within the wellbore adjacent to said formation, wherein said wellbore has a first pressure substantially equal to a minimum hydrostatic pressure achievable in the wellbore and said formation has a second pressure, and wherein the pressure gradient is the difference between the first and second pressures, and the pressure gradient is of insufficient magnitude to clear the perforated tunnel by the cleaning surge flow if conventional charges were detonated to form the perforated tunnel;e) detonating the reactive shaped charge of the charge carrier to create the perforated tunnel in the formation such that an explosive exothermic reaction takes place between materials comprising the liner component of the reactive shaped charge, and creating the dynamic underbalance;f) creating the cleaning surge flow between the formation and the internal volume of the carrier under influence of the dynamic underbalance; andg) substantially clearing the perforated tunnel in the formation, the perforated tunnel substantially free of a crush zone which would otherwise be formed if conventional charges were used;whereby, the method of detonating the reactive shaped charges has the effect of reducing shot density while providing a greater number of substantially cleared perforated tunnels as compared to detonating conventional charges. 2. The method of claim 1, wherein said detonating step causes a first and a second explosive event, the second explosive event substantially cleaning a tunnel depth substantially equal to the total depth of penetration of the perforated tunnel. 3. The method of claim 2 wherein said second explosive event occurs within 100 microseconds of said detonation. 4. The method of claim 2 wherein said second explosive event is substantially contained within a perforated tunnel. 5. The method of claim 2 wherein said second explosive event occurs within 200-300 microseconds of said detonation. 6. The method of claim 1 wherein the step of providing a charge carrier comprises providing a charge carrier of a grade of steel other than G-130, G-135, or G-140. 7. The method of claim 1 wherein the step of detonating such that explosive reaction takes place, results in projecting molten metal of the liner components into the perforated tunnel created by the reactive shaped charges. 8. The method of claim 7, wherein the formation comprises water, the molten metal reacting with the water. 9. The method of claim 1 wherein the detonation further comprises two explosive events upon detonating; a first explosive event triggering a second reactive explosive event, the second explosive event comprising the explosive exothermic reaction. 10. A method for perforating a well for the enhancement of dynamic underbalance in a perforating system within a wellbore adjacent to an underground hydrocarbon bearing formation, the method improving inflow and outflow performance relative to performance achieved with conventional shaped charges, said method comprising the steps of: a) providing a charge carrier having a substantially empty internal volume and comprising a plurality of cavities for receiving charges;b) partially filling the charge carrier by filling only some selected cavities of the charge carrier with a charge comprising a reactive shaped charge having a liner component, the number of cavities filled selected based on enhancing the dynamic underbalance that causes surge flow of explosion debris from the formation to the charge holder, after charge detonation;c) positioning the charge carrier within the wellbore adjacent to said formation, wherein said wellbore comprises a first pressure substantially equal to a minimum hydrostatic pressure achievable in the wellbore and said formation comprises a second pressure, the first pressure lower than the second pressure, and wherein a maximum pressure gradient between the first and second pressures is of insufficient magnitude to clear perforated tunnels by surge flow if conventional charges were used; andd) forming the perforated tunnels in the formation by detonating the reactive shaped charges to create a first explosive event and second explosive event, wherein the first explosive event creates the perforated tunnels within the adjacent formation, and wherein the second explosive event is created by an explosive exothermic reaction between materials comprising the shaped charge liner component, the second explosive event substantially clearing the perforated tunnels formed in the formation by the first explosive event;whereby, the use of the reactive shaped charges results in the surge flow as compared to conventional explosive charges thereby substantially freeing the perforated tunnels of a crush zone, resulting in enhanced hydrocarbon production from the formation. 11. The method of claim 10 wherein said second explosive event occurs within 100 microseconds of said detonation. 12. The method of claim 10 wherein said second explosive event is substantially contained within the perforated tunnel. 13. The method of claim 10 wherein said second explosive event occurs within 200-300 microseconds of said detonation. 14. The method of claim 10 wherein the step of providing a charge carrier comprises providing a charge carrier of a grade of steel other than G-130, G-135, or G-140. 15. The method of claim 10 wherein the step of detonating such that explosive reaction takes place results in projecting molten metal of the liner components into the perforated tunnel created by the reactive shaped charges. 16. The method of claim 15 wherein the formation comprises water, the molten metal reacting with the water. 17. A method for perforating a wellbore with a perforating system within the wellbore adjacent to an underground hydrocarbon bearing formation, the method improving inflow and outflow performance relative to performance achieved with conventional shaped charges, said method comprising the steps of: a) selecting a wellbore wherein a maximum pressure gradient achievable between the formation and the wellbore, with minimum achievable hydrostatic pressure in the wellbore, is insufficient to create a cleaning surge flow when using conventional charges for creating perforated tunnels;b) providing a charge carrier having a substantially empty internal volume and comprising a plurality of cavities for receiving charges;c) filling selective cavities of the charge carrier with a charge comprising a reactive shaped charge having a liner component into the charge carrier, the number of cavities filled selected based on enhancing an underbalance effect that causes back flow of explosion debris from the formation to the charge carrier, after the charges are detonated, and based on maintaining effective shot-density compared to a fully loaded charge carrier;d) positioning the selectively filled charge carrier within the wellbore adjacent to the formation, wherein said wellbore has a first pressure substantially equal to a minimum hydrostatic pressure achievable in the wellbore and said formation comprises a second pressure higher than the first pressure, and the formation comprising water therein; ande) forming the perforated tunnels in the formation by detonating the charge carrier to create a first and second explosive event, wherein the first explosive event creates the perforated tunnels within the adjacent formation, and wherein the second explosive event is created by an explosive exothermic reaction between materials comprising the shaped charge liner component, the second explosive event resulting in projecting molten metal of the liner component into the perforated tunnels created by the reactive shaped charges, the molten metal reacting with the water in the formation thereby substantially clearing the perforated tunnels formed in the formation by the first explosive event, the second explosive event substantially confined within the perforated tunnels;whereby, the method provides a higher effective shot density relative to detonating a charge carrier without the reactive shaped charges, while reducing shot density, and the method creates a dynamic underbalance around the charge carrier as a result of detonation of the reactive shaped charges, the dynamic underbalance of sufficient magnitude to create the cleaning surge flow.