Process For Directed Fracking Of An Underground Formation Into Which At Least One Directional Well Has Been Sunk

Abstract

A process for fracking an underground formation, comprising at least the steps of a) sinking a directional well ( 1 ) comprising a quasi-vertical section ( 11 ) and a quasi-horizontal section ( 12 ) into the underground formation, b) introducing hollow bodies (HB) and a detonatable free-flowing explosive (FE) into the directional well ( 1 ) and c) initiating the detonation in the directional well ( 1 ), wherein the hollow bodies (HB) have a density (D HB ) and the detonatable free-flowing explosive (FE) has a density (D FE ) and (D HB ) is less than (D FE ), and the end of process step b) is followed by and process step c) is preceded by a rest phase, the result of which is that the hollow bodies (HB) float in the detonatable free-flowing explosive (FE).

1 . A process for fracking an underground formation, comprising at least the steps of
 a) sinking a directional well ( 1 ) comprising a quasi-vertical section ( 11 ) and a quasi-horizontal section ( 12 ) into the underground formation,   b) introducing hollow bodies (HB) and a detonatable free-flowing explosive (FE) into the directional well ( 1 ) and   c) initiating the detonation in the directional well ( 1 ),   
       wherein the hollow bodies (HB) have a density (D HB ) and the detonatable free-flowing explosive (FE) has a density (D FE ) and (D HB ) is less than (D FE ), and the end of process step b) is followed by and process step c) is preceded by a rest phase, the result of which is that the hollow bodies (HB) float in the detonatable free-flowing explosive (FE). 
     
     
         2 . The process according to  claim 1 , wherein the hollow bodies (HB) have positive buoyancy in the detonatable free-flowing explosive (FE). 
     
     
         3 . The process according to  claim 1 , wherein the majority of the hollow bodies (HB) used in process step b) and of the explosive (FE) are introduced into the quasi-horizontal part of the well ( 12 ). 
     
     
         4 . The process according to  claim 1 , wherein the density (D HB ) of the hollow bodies (HB) is in the range from 0.2 to 0.9 g/cm 3 . 
     
     
         5 . The process according to  claim 1 , wherein the density (D FE ) of the explosive is in the range from 0.95 to 2 g/cm 3 . 
     
     
         6 . The process according to  claim 1 , wherein the hollow bodies (HB) used are spherical hollow bodies having a diameter in the range from 1 μm to 5 mm. 
     
     
         7 . The process according to  claim 1 , wherein the hollow bodies (HB) used are cenospheres having a shell comprising silicon oxide, aluminum oxide and iron oxide. 
     
     
         8 . The process according to  claim 1 , wherein the explosive (FE) comprises a fuel component and an oxidizing agent. 
     
     
         9 . The process according to  claim 1 , wherein a detonatable free-flowing mixture (DM) is introduced in process step b) into the directional well ( 1 ) comprising hollow bodies (HB) and the explosive (FE). 
     
     
         10 . The process according to  claim 1 , wherein the introduction of the hollow bodies (HB) and of the explosive (FE) in process step b) is preceded by introduction of a free-flowing tamping composition ( 7 ) into the directional well. 
     
     
         11 . The process according to  claim 9 , wherein the mixture (DM) comprises 5 to 50% by volume of hollow bodies (HB), based on the total volume of the mixture (DM) used in process step b). 
     
     
         12 . The process according to  claim 9 , wherein the rest phase is in the range from 1 hour to 3 days. 
     
     
         13 . The process according to  claim 10 , wherein a mixture (DM) additionally comprising hollow bodies (HBn) having neutral buoyancy in the explosive (FE) is used in process step b). 
     
     
         14 . The process according to  claim 1 , wherein the hollow bodies (HB) used are cylindrical hollow bodies having a partial metallic coating. 
     
     
         15 . The process according to  claim 1 , wherein the detonation in process step c) is initiated by a chemical or electrical detonator ( 24 ).