Geothermal circulation system

Abstract

The invention relates to a method for configuring a geothermal circulation system in a target underground region, comprising at least one injection wellbore ( 1 ) and at least one production wellbore ( 2 ), a hydraulic connection being created between the injection wellbore ( 1 ) and the production wellbore ( 2 ) via a crack system ( 4, 4′ ) in the target underground region, and a heat transfer medium being circulated via the injection wellbore ( 1 ), crack system ( 4, 4′ ), and production wellbore ( 2 ), comprising the steps of creating a plurality of cracks ( 4, 4′ ) in the target underground region by the incremental hydraulic separation of short wellbore sections and hydraulic crack generation starting from the respective separated wellbore section. The invention further relates to an arrangement for a geothermal circulation system in a target underground region, comprising at least one injection wellbore and at least one production wellbore, wherein a hydraulic connection is established in the target underground region between the injection wellbore and the production wellbore via a crack system, wherein the injection wellbore and the production wellbore in the target underground region have wellbore segments that are deflected at angles (α, β) of 0° to 80° to the horizontal line, and a plurality of cracks are provided for the hydraulic connection between the injection wellbore and production wellbore.

1 . A method of forming a geothermal circulation system in a target underground area (Z), the method comprising:
 forming at least one injection wellbore ( 1 ) and at least one production wellbore ( 2 ),   forming a hydraulic connection between the injection wellbore ( 1 ) and the production wellbore ( 2 ) through a crack system comprising a number of cracks ( 4 ,  4 ′) in the target underground area (Z), and   circulating a heat transfer medium through the injection wellbore ( 1 ), crack system ( 4 ,  4 ′) and production wellbore ( 2 ),   wherein said number of cracks ( 4 ,  4 ′) in the target substrate area (Z) is created by
 stepwise hydraulic separating or insulating short hydraulic wellbore segments and 
 generating cracks hydraulically, said cracks emanating from the respectively separated or insulated wellbore segments. 
   
     
     
         2 . The method according to  claim 1 , wherein said injection and production wellbores ( 1 ,  2 ) are so deflected from vertical during the drilling, that the wellbores pass through the target substrate area (Z) at an angle offset from vertical up to horizontal. 
     
     
         3 . The method according to  claim 1 , wherein the injection and/or production wellbore (s) ( 1 ,  2 ), prior to hydraulic crack generation, are lined and cemented, and that a perforation ( 15 ) is provided in the piping or lining ( 13 ) associated with each hydraulic crack generation. 
     
     
         4 . The method according to  claim 1 , wherein the injection wellbore ( 1 ) and the production wellbore ( 2 ) are drilled and deflected in such a manner that they include essentially horizontal wellbore sections ( 11 ,  21 ), which run antiparallel to each other at a predetermined depth. 
     
     
         5 . The method according to  claim 1 , wherein, in a target underground area (Z) with a fault zone(s), hydraulic crack generation takes place from the injection wellbore ( 1 ) as well as the production wellbore ( 2 ), so that the generated cracks extend from the respective wellbore into the fault zone (S) and therewith establish a hydraulic connection between the injection wellbore ( 1 ) and the production wellbore ( 2 ) via the fault zone (S). 
     
     
         6 . The method according to  claim 1 , wherein a first borehole, particularly the injection wellbore ( 1 ), is drilled first, and hydraulic crack generation takes place from this initial drill hole, and after the creation of a number of cracks ( 4 ), these are passed through by a second borehole, especially the production wellbore ( 2 ). 
     
     
         7 . The method according to  claim 1 , wherein a first borehole, particularly the injection wellbore ( 1 ), is drilled first, and wherein a second borehole, especially the production wellbore ( 2 ) is sunk in such a manner, that by generating a large number of cracks ( 4 ,  4 ′) emanating from the two boreholes, an intersecting crack system, and thus hydraulic connection between the two boreholes, is produced. 
     
     
         8 . The method according to  claim 6 , wherein the second borehole is lined or encased and cemented, after which the piping ( 13 ) is perforated at dedicated drill hole sections and there a selective hydraulic crack formation takes place out of this second borehole. 
     
     
         9 . The method according to  claim 2 , wherein the crack generation is performed using a dual packing guided on a tube pole within the perforated piping or casing ( 13 ). 
     
     
         10 . A well for extracting geothermal energy via a geothermal circulation system in a target underground area (Z) consisting of at least one injection wellbore ( 1 ) and at least one production wellbore ( 2 ), with a hydraulic connection between the injection wellbore ( 1 ) and the production wellbore ( 2 ) provided by a crack system ( 4 . 4 ′) in the target underground area (Z), wherein
 the injection wellbore ( 1 ) and the production wellbore ( 2 ) in the target underground area (Z) include wellbore segments ( 11 ,  21 ) deflected at an angle (α, β) of from 0° to 80° to the horizontal (H), and
 a number of cracks ( 4 ,  4 ′) are provided for the hydraulic connection between injection wellbore ( 1 ) and production wellbore ( 2 ). 
   
     
     
         11 . The well according to  claim 10 , wherein the wellbore segments ( 11 ,  21 ) of the injection wellbore ( 1 ) and the production wellbore ( 2 ) in the target underground area (Z) run substantially parallel to each other or at an acute angle to each other, so that the distance (a) between the holes towards the bore bottom ( 13 ,  23 ) decreases, or are arranged antiparallel. 
     
     
         12 . The well according to  claim 10 , wherein the angle (α, β) is from 0° to 60°, in particular from 0° to 45°, preferably 0° to 20°. 
     
     
         13 . The well according to  claim 10 , wherein at least six cracks ( 4 ,  4 ′), preferably 20 to 50 cracks, are provided. 
     
     
         14 . The well according to  claim 10 , wherein the injection wellbore ( 1 ) a casing ( 13 ) and cementation ( 14 ) are provided, wherein perforations ( 15 ) are provided in the casing ( 13 ) at the intended sites of crack formation. 
     
     
         15 . The well according to  claim 10 , wherein the production wellbore ( 2 ) has a cementing and casing, and wherein perforations are provided in the casing at desired sites of crack formation.