Methods for the enhancement and stimulation of oil and gas production in shales

Abstract

By removing material of low permeability from within and around a perforation tunnel and creating at least one fracture at the tip of a perforation tunnel, injection parameters and effects such as outflow rate and, in the case of multiple perforation tunnels benefiting from such cleanup, distribution of injected fluids along a wellbore are enhanced. Following detonation of a charge carrier, a second explosive event is triggered within a freshly made tunnel, thereby substantially eliminating a crushed zone and improving the geometry and quality (and length) of the tunnel. In addition, this action creates substantially debris-free tunnels and relieves the residual stress cage, resulting in perforation tunnels that are highly conducive to injection under fracturing conditions for disposal and stimulation purposes, and that promote even coverage of injected fluids across the perforated interval.

1 . A method for perforating a well and for the enhancement of injection activities and stimulation of oil or gas production in an underground formation, the method comprising:
 loading a reactive liner shaped charge within a charge carrier, the reactive liner shaped charge having a reactive liner;   positioning the charge carrier down a wellbore adjacent to the underground formation, the underground formation including shales;   detonating a high explosive in the reactive liner shaped charge to cause a first explosive event; and   triggering a second explosive event as a result of the first explosive event, the second explosive event created by exothermic interaction between components of the reactive liner, the second explosive events clearing the perforation tunnel of an internal crush zone.   
     
     
         2 . The method of  claim 1 , wherein the perforation tunnel includes a fracture at a tip of the perforation, and further comprising stimulating the formation by forcing injected fluid out of the perforation tunnel through the fracture at the tip of the perforation tunnel into the underground formation. 
     
     
         3 . The method of  claim 1 , whereby the reactive liner comprises at least three components selected from metals and oxides of metals such that the reactive liner is subject to explosive exothermic intermetallic reaction under detonation conditions caused by the high explosive. 
     
     
         4 . The method of  claim 1 , whereby the second explosive event clearing the perforation tunnel of the internal crush zone produces a clear tunnel depth, wherein a depth of the clear tunnel is equal to the total depth of penetration of the perforation tunnel. 
     
     
         5 . The method of  claim 1 , further comprising:
 injecting a fluid into the wellbore to fracture the underground formation, wherein the step of injecting comprises injecting a fluid selected from the group consisting of brines, acids, bases, gels, emulsions, enzymes, chemical breakers, and polymers.   
     
     
         6 . The method of  claim 3 , wherein the at least three components of the reactive liner shaped charge are selected from Al, Ce, Li, Mg, Mo, Ni, Nb, Pb, Pd, Ta, Ti, Zn, and Zr. 
     
     
         7 . The method of  claim 1 , wherein the reactive liner shaped charge includes a component selected from the Group IV elements. 
     
     
         8 . The method of  claim 1 , wherein the components of the reactive liner include Al, Ni, and Pb. 
     
     
         9 . A method for perforating a well for the enhancement of injection activities and stimulation of oil or gas production in an underground formation, said method comprising the steps of:
 loading a plurality of reactive liner shaped charges within a charge carrier, each of the plurality of reactive shaped charges including a reactive liner;   positioning the charge carrier down a wellbore adjacent to the underground formation, wherein the underground formation includes shales; and   detonating a high explosive in each of the plurality of reactive liner shaped charges, the step of detonating creating a first explosive event in each of the plurality of reactive liner shaped charges, each first explosive triggering a second explosive event in each of the plurality of reactive liners, the second explosive event created by exothermic interaction between components of the reactive liner, the second explosive events clearing the perforation tunnel of an internal crush zone.   
     
     
         10 . The method of  claim 9 , wherein the reactive liner comprises a metal selected from Al, Ce, Li, Mg, Mo, Ni, Nb, Pb, Pd, Ta, Ti, Zn, or Zr. 
     
     
         11 . The method of  claim 10 , wherein the reactive liner further comprises a non-metal of Group IV. 
     
     
         12 . The method of  claim 9 , wherein the perforation includes a fracture at a tip of the perforation, and further comprising stimulating the formation by forcing injected fluid out of the perforation tunnel through the fracture at the tip of the perforation tunnel into the underground formation. 
     
     
         13 . The method of  claim 9 , wherein the second explosive event clears a crush zone of the perforation tunnel to produce a clear tunnel depth having an improved permeability as compared to a permeability with crush zone in place. 
     
     
         14 . The method of  claim 9 , further comprising a step of injecting fluids after the step of detonating; whereby the step of injecting fluids is at an increased fluid injection rate as compared to a method using a charge without a reactive liner. 
     
     
         15 . The method of  claim 14 , whereby a distribution of injected fluids across the underground formation is improved as compared to using a charge without a reactive liner. 
     
     
         16 . A method for perforating a well and minimizing near wellbore pressure losses during injection and stimulation of oil or gas production in an underground formation, said method comprising the steps of:
 loading a reactive liner shaped charge within a charge carrier, the reactive liner shaped charge having a reactive liner;   positioning the charge carrier down a wellbore adjacent to the underground formation, the formation including shales or carbonates;   detonating a high explosive in the reactive liner shaped charge to create a first explosive event;   triggering a second explosive event by energy of the first explosive event, wherein the second explosive event is created by exothermic interaction between components of the reactive liner, the first and second explosive events creating a perforation tunnel in the underground formation, clearing the perforation tunnel of debris and inducing at least one fracture at a tip of the perforation tunnel; and   injecting a fluid into the perforation tunnel under pressure to stimulate oil or gas production;   wherein the perforation tunnel has an improved permeability as compared to permeability with the crush zone in place, and whereby the detonating of the reactive liner shaped charge minimizes near wellbore pressure losses during fluid injection, relative to methods using a charge without a reactive liner.   
     
     
         17 . The method of  claim 16 , wherein the components of the reactive liner include at least two metals selected from Al, Ce, Li, Mg, Mo, Ni, Nb, Pb, Pd, Ta, Ti, Zn, or Zr. 
     
     
         18 . The method of  claim 17 , wherein the reactive liner further comprises a non-metal of Group IV. 
     
     
         19 . The method of  claim 16 , wherein the perforation includes a fracture at a tip of the perforation, and further comprising stimulating the formation by forcing injected fluid out of the perforation tunnel through the fracture at the tip of the perforation tunnel into the underground formation. 
     
     
         20 . The method of  claim 16 , wherein the components of the reactive liner are Al and Ni, and the liner further includes Pb. 
     
     
         21 - 30 . (canceled)