Apparatus and method for penetrating oilbearing sandy formations, reducing skin damage and reducing hydrocarbon viscosity

Abstract

A shaped charge and a method of using such to provide for large and effective perforations in oil bearing sandy formations while causing minimal disturbance to the formation porosity is described. This shaped charge uses a low-density liner having a filler material that is enclosed by outer walls made, preferably, of plastic or polyester. The filler material is preferably a powdered metal or a granulated substance, which is left largely unconsolidated. The preferred filler material is aluminum powder, or aluminum particles, that are coated with an oxidizing substance, such as TEFLON®, permitting a secondary detonation reaction inside the formation following jet penetration. The filled liner is also provided with a metal cap to aid penetration of the gun scallops, the surrounding borehole casing and the cement sheath. The metal cap forms the leading portion of the jet, during detonation. The remaining portion of the jet is formed from the low-density filler material, thereby resulting in a more particulated jet. The jet results in less compression around the perforation tunnel and less skin damage to the proximal end of the perforation tunnel.

1 . A shaped charge comprising: 
 a charge case;    an explosive charge;    a liner for retaining the explosive charge within the case, the liner comprising: 
 a substantially contiguous first liner membrane;  
 a substantially contiguous second liner membrane; and  
 a particulated filler material disposed between the first and second liner membranes, which is substantially unconsolidated.  
   
   
   
       2 . The shaped charge of  claim 1  wherein the liner further comprises a metal cap disposed upon the first liner membrane.  
   
   
       3 . The shaped charge of  claim 1  wherein the filler comprises powdered metal.  
   
   
       4 . The shaped charge of  claim 1  wherein the filler material is a blend of coarse and fine particles.  
   
   
       5 . The shaped charge of  claim 1  wherein the first and second liner membranes are comprised of plastic.  
   
   
       6 . The shaped charge of  claim 1  wherein the first and second liner membranes are comprised of polyester.  
   
   
       7 . The shaped charge of  claim 1  wherein the first and second liner membranes are comprised of fiberglass.  
   
   
       8 . The shaped charge of  claim 1  wherein the first and second liner membranes are comprised of glass.  
   
   
       9 . The shaped charge of  claim 3  wherein particles of the powdered metal have a polymer coating.  
   
   
       10 . The shaped charge of  claim 9  wherein the powdered metal comprises aluminum and the polymer comprises TEFLON®.  
   
   
       11 . The shaped charge of  claim 10  wherein the aluminum is passivated by a polymer coating.  
   
   
       12 . The shaped charge of  claim 1  wherein the filler material comprises hollow metal pellets.  
   
   
       13 . The shaped charge of  claim 1  wherein the filler material comprises glass balloons.  
   
   
       14 . The shaped charge of  claim 1  wherein the filler material comprises nano particles of material from the group consisting essentially of aluminum, copper, tungsten, copper-coated tungsten, and TEFLON®-coated aluminum.  
   
   
       15 . The shaped charge of  claim 1  wherein the first and second membranes are contiguously affixed to one another to completely enclose the filler material.  
   
   
       16 . The shaped charge of  claim 1  wherein the filler material has a density that is below formation density.  
   
   
       17 . The shaped charge of  claim 1  wherein the filler material has a density that is below 2.7 g/cc.  
   
   
       18 . The shaped charge of  claim 3  wherein the powdered metal comprises tungsten.  
   
   
       19 . The shaped charge of  claim 18  wherein the powdered tungsten is coated with copper.  
   
   
       20 . A shaped charge comprising: 
 a charge case;    an explosive charge;    a liner for retaining the explosive charge within the case, the liner comprising: 
 an outer liner membrane; and  
 a filler material disposed encapsulated within the liner membrane, the filler material having a density that approximates formation density  
   
   
   
       21 . The shaped charge of  claim 20  wherein the density if the filler material is equal to or less than, or higher than, 2.7 g/cc.  
   
   
       22 . The shaped charge of  claim 20  wherein the filler material is particulated.  
   
   
       23 . The shaped charge of  claim 20  wherein the filler material comprises powdered aluminum.  
   
   
       24 . he shaped charge of  claim 23  wherein the filler material further comprises TEFLON®.  
   
   
       25 . The shaped charge of  claim 20  wherein the liner has a shape from the group consisting essentially of conical, cylindrical, trumpet, tulip, ball, and hemispherical.  
   
   
       26 . A method of perforating a formation comprising: 
 generating a perforating jet having a metal precursor portion followed by a substantially particulated portion;    penetrating a wellbore casing with said metal precursor portion;    kissing the formation with said precursor portion; and    penetrating said formation with said particulated jet to form a perforation.    
   
   
       27 . The method of  claim 26  further comprising the step of initiating a secondary detonation reaction within the formation to open pores within the formation surrounding the perforation.  
   
   
       28 . The method of  claim 27  wherein the step of initiating a secondary detonation reaction comprises heating air-filled pores in unconsolidated aluminum and rapidly oxidizing unconsolidated aluminum via proximity of fluorine atoms in a TEFLON® coating.  
   
   
       29 . The method of  claim 26  wherein the secondary burning reaction further comprises oxidizing aluminum through a TEFLON® coating.  
   
   
       30 . The method of  claim 26  further comprising the step of disposing unreacted polymer within the formation to reduce fluid viscosity.  
   
   
       31 . The method of  claim 26  further comprising the step of disposing unreacted TEFLON® within the formation to reduce fluid viscosity.  
   
   
       32 . An explosively formed penetrator comprising: 
 a charge case;    an explosive charge within said charge case;    a liner for retaining the explosive charge within the case, the liner comprising: 
 a substantially contiguous first liner membrane;  
 a substantially contiguous second liner membrane; and  
 a particulated filler material disposed between the first and second liner membranes, the filler material being substantially unconsolidated.  
   
   
   
       33 . The explosively formed penetrator of  claim 32  wherein the explosively formed penetrator further comprises a metal cap disposed upon the first liner membrane.  
   
   
       34 . The explosively formed penetrator of  claim 32  wherein the liner forming the precursor jet is conformal to the charge case.