Methods and apparatus for drilling, completing and configuring U-tube boreholes

Abstract

A borehole network including first and second end surface locations and at least one intermediate surface location interconnected by a subterranean path, and a method for connecting a subterranean path between a first borehole including a directional section and a second borehole including a directional section. A directional drilling component is drilled in at least one of the directional sections to obtain a required proximity between the first and second boreholes. An intersecting component is drilled, utilizing magnetic ranging techniques, from one directional section to provide a borehole intersection between the first and second boreholes, thereby connecting the subterranean path.

1 . A method for connecting a subterranean path between a first borehole and a second borehole, wherein the first borehole is comprised of a first surface location and a first borehole directional section and wherein the second borehole is comprised of a second surface location and a second borehole directional section, the method comprising: 
 (a) drilling a directional drilling component in at least one of the first borehole directional section or the second borehole directional section in order to obtain a required proximity between the first borehole and the second borehole;    (b) drilling an intersecting component from one of the first borehole directional section or the second borehole directional section in order to provide a borehole intersection between the first borehole and the second borehole, thereby connecting the subterranean path.    
   
   
       2 . The method as claimed in  claim 1  wherein a distal end of the first borehole directional section and a distal end of the second borehole directional section are offset following the drilling of the directional drilling component.  
   
   
       3 . The method as claimed in  claim 2  wherein the intersecting component is drilled in the second borehole and wherein the distal end of the second borehole directional section is offset vertically from the distal end of the first borehole directional section following the drilling of the directional drilling component such that the distal end of the second borehole directional section is above the distal end of the first borehole directional section.  
   
   
       4 . The method as claimed in  claim 3  wherein the distal end of the second borehole directional section and the distal end of the first borehole directional section are substantially aligned in a vertical plane following the drilling of the directional drilling component.  
   
   
       5 . The method as claimed in  claim 4  wherein a distal end of the first borehole directional section and a distal end of the second borehole directional section are substantially parallel to each other following the drilling of the directional drilling component.  
   
   
       6 . The method as claimed in  claim 2  wherein the borehole intersection is located within a circular area defined by the first surface location and the second surface location.  
   
   
       7 . The method as claimed in  claim 6  wherein the first borehole directional section has an azimuthal path and wherein the azimuthal path of the first borehole directional section extends substantially in a direction toward the second surface location.  
   
   
       8 . The method as claimed in  claim 7  wherein the second borehole directional section has an azimuthal path and wherein the azimuthal path of the second borehole directional section extends substantially in a direction toward the first surface location.  
   
   
       9 . The method as claimed in  claim 2  wherein an inclination of the distal end of the first borehole directional section is substantially horizontal.  
   
   
       10 . The method as claimed in  claim 9  wherein an inclination of the distal end of the second borehole directional section is substantially horizontal.  
   
   
       11 . The method as claimed in  claim 2  wherein drilling the intersecting component is comprised of providing a relatively smooth transition between the first borehole and the second borehole.  
   
   
       12 . The method as claimed in  claim 11  wherein drilling the intersecting component is comprised of drilling an S-shape curve.  
   
   
       13 . The method as claimed in  claim 12  wherein the S-shape curve is comprised of a first curve having a first curve radius and an opposing second curve having a second curve radius and wherein the first curve radius and the second curve radius are substantially equal.  
   
   
       14 . The method as claimed in  claim 12  wherein the first curve has a first curve length, wherein the second curve has a second curve length, and wherein the first curve length and the second curve length are substantially equal.  
   
   
       15 . The method as claimed in  claim 2  wherein drilling the intersecting component is comprised of using a magnetic ranging system to guide the drilling of the intersecting component.  
   
   
       16 . The method as claimed in  claim 15  wherein the magnetic ranging system is comprised of a magnetic guidance tool system and wherein the required proximity of the first borehole and the second borehole following the drilling of the directional drilling component is less than about 30 meters.  
   
   
       17 . The method as claimed in  claim 15  wherein the magnetic ranging system is comprised of a rotating magnet ranging system and wherein the required proximity of the first borehole and the second borehole following the drilling of the directional drilling component is less than about 70 meters.  
   
   
       18 . The method as claimed in  claim 15  wherein drilling the directional drilling component is comprised of providing an overlap between the distal end of the first borehole directional section and the distal end of the second borehole directional section following the drilling of the directional drilling component in order to facilitate drilling of the intersecting component using the magnetic ranging system.  
   
   
       19 . The method as claimed in  claim 2  wherein drilling the directional drilling component is comprised of drilling in the second borehole directional section and wherein drilling the directional drilling component is comprised of providing a sidetrack location in the second borehole directional section before the distal end of the second borehole directional section.  
   
   
       20 . The method as claimed in  claim 19  wherein the sidetrack location is comprised of a discontinuity, a radius or a bend in the second borehole directional section.  
   
   
       21 . The method as claimed in  claim 2  wherein the intersecting component is drilled from the second borehole directional section, wherein the first borehole directional section has a gauge, wherein drilling the directional drilling component is performed using a drill bit having a gauge, and wherein the gauge of the drill bit used for drilling the intersecting component is less than the gauge of the first borehole directional section.  
   
   
       22 . The method as claimed in  claim 21 , further comprising enlarging the gauge of the intersecting component after the borehole intersection has been provided so that the intersecting component has a full gauge relative to the first directional section.  
   
   
       23 . The method as claimed in  claim 22  wherein enlarging the gauge of the intersecting component is comprised of passing a hole opener through the borehole intersection.  
   
   
       24 . A method for connecting a subterranean path between a target borehole and an intersecting borehole by drilling an intersecting component between the target borehole and the intersecting borehole to provide a borehole intersection, wherein the target borehole is comprised of a target borehole surface location and a target borehole directional section, wherein the intersecting borehole is comprised of an intersecting borehole surface location and an intersecting borehole directional section, and wherein a distal end of the target borehole directional section and a distal end of the intersecting borehole directional section are offset, the method comprising: 
 (a) placing a first magnetic device comprising one of a magnet or a magnetic instrument at an initial position in the target borehole;    (b) placing a drill string comprising a drill bit and a second magnetic device comprising the other of the magnet or the magnetic instrument in the intersecting borehole;    (c) performing an initial magnetic ranging survey in order to obtain data representing the relative positions of the first magnetic device and the second magnetic device;    (d) drilling, in the intersecting borehole, a portion of the intersecting component toward the target borehole;    (e) moving the first magnetic device in the target borehole to a new position in the target borehole which will facilitate a further magnetic ranging survey;    (f) performing the further magnetic ranging survey in order to obtain data representing the relative positions of the first magnetic device and the second magnetic device; and    (g) repeating (d), (e) and (f) until the borehole intersection is provided between the target borehole and the intersecting borehole.    
   
   
       25 . The method as claimed in  claim 24  wherein an overlap is provided between the distal end of the target borehole directional section and the distal end of the intersecting borehole directional section.  
   
   
       26 . The method as claimed in  claim 24  wherein the first magnetic device is comprised of the magnet and wherein the second magnetic device is comprised of the magnetic instrument.  
   
   
       27 . The method as claimed in  claim 26  wherein the magnet is comprised of a solenoid oriented with the magnet poles aligned substantially parallel to the target borehole directional section.  
   
   
       28 . The method as claimed in  claim 27  wherein performing the initial magnetic ranging survey and performing the further magnetic ranging survey comprises energizing the solenoid with a varying electrical current so that the solenoid provides a varying magnetic field.  
   
   
       29 . The method as claimed in  claim 28  wherein the offset is less than about 30 meters.  
   
   
       30 . The method as claimed in  claim 24  wherein the first magnetic device is comprised of the magnetic instrument and wherein the second magnetic device is comprised of the magnet.  
   
   
       31 . The method as claimed in  claim 30  wherein the magnet is comprised of a magnet assembly oriented with the magnet poles aligned substantially transverse to the drill string axis.  
   
   
       32 . The method as claimed in  claim 31  wherein performing the initial magnetic ranging survey and performing the further magnetic ranging survey comprises rotating the drill string so that the magnet assembly provides a varying magnetic field.  
   
   
       33 . The method as claimed in  claim 32  wherein the offset is less than about 70 meters.  
   
   
       34 . The method as claimed in  claim 24  wherein the intersecting component is comprised of a curve.  
   
   
       35 . The method as claimed in  claim 34  wherein the curve is comprised of an S-shape curve, wherein the S-shape curve is comprised of a first curve and an opposing second curve, and wherein the method is comprised of drilling the first curve and the second curve in order to provide the borehole intersection.  
   
   
       36 . The method as claimed in  claim 35  wherein the first curve has a first curve radius, wherein the second curve has a second curve radius, and wherein the first curve radius and the second curve radius are substantially equal.  
   
   
       37 . The method as claimed in  claim 35  wherein the first curve has a first curve length, wherein the second curve has a second curve length, and wherein the first curve length and the second curve length are substantially equal.  
   
   
       38 . The method as claimed in  claim 24  wherein the target borehole directional section has a gauge, wherein the drill bit has a gauge, and wherein the gauge of the drill bit is less than the gauge of the target borehole directional section.  
   
   
       39 . The method as claimed in  claim 38 , further comprising enlarging the gauge of the intersecting component after the borehole intersection has been provided so that the intersecting component has a full gauge relative to the target borehole directional section.  
   
   
       40 . The method as claimed in  claim 39  wherein enlarging the gauge of the intersecting component is comprised of passing a hole opener through the borehole intersection.  
   
   
       41 . The method as claimed in  claim 24  wherein the borehole intersection is located within a circular area defined by the target borehole surface location and the intersecting borehole surface location.  
   
   
       42 . The method as claimed in  claim 24  wherein the borehole intersection is located outside of a circular area defined by the target borehole surface location and the intersecting borehole surface location.  
   
   
       43 . The method as claimed in  claim 24  wherein the distal end of the intersecting borehole directional section is offset vertically from the distal end of the target borehole directional section such that the distal end of the intersecting borehole directional section is above the distal end of the target borehole directional section.  
   
   
       44 . The method as claimed in  claim 43  wherein the distal end of the intersecting borehole directional section and the distal end of the target borehole directional section are substantially aligned in a vertical plane.  
   
   
       45 . The method as claimed in  claim 44  wherein the distal end of the intersecting borehole directional section and the distal end of the target borehole directional section are substantially parallel to each other.  
   
   
       46 . The method as claimed in  claim 24  wherein an inclination of the distal end of the target borehole directional section is substantially horizontal.  
   
   
       47 . The method as claimed in  claim 46  wherein an inclination of the distal end of the intersecting borehole is substantially horizontal.  
   
   
       48 . A borehole network, comprising: 
 (a) a first end surface location;    (b) a second end surface location;    (c) at least one intermediate surface location located between the first end surface location and the second end surface location; and    (d) a subterranean path connecting the first end surface location, the intermediate surface location, and the second end surface location.    
   
   
       49 . The borehole network as claimed in  claim 48 , further comprising a sealing mechanism for sealing the intermediate surface location from the subterranean path.  
   
   
       51 . The borehole network as claimed in  claim 48 , further comprising a pump associated with the intermediate surface location, for pumping a fluid through the subterranean path.  
   
   
       52 . The borehole network as claimed in  claim 48 , further comprising a surface borehole extending between the subterranean path and the intermediate surface location.  
   
   
       53 . The borehole network as claimed in  claim 52  wherein the subterranean path is comprised of a pair of lateral boreholes which connect with the surface borehole.  
   
   
       54 . The borehole network as claimed in  claim 53 , further comprising a lateral junction for connecting the surface borehole and the pair of lateral boreholes.  
   
   
       55 . The borehole network as claimed in  claim 52 , further comprising a pump located at the intermediate surface location, for pumping a fluid through the subterranean path.  
   
   
       56 . The borehole network as claimed in  claim 52 , further comprising a pump located in the surface borehole, for pumping a fluid through the subterranean path.  
   
   
       57 . The borehole network as claimed in  claim 56  wherein the pump is an electrical submersible pump.  
   
   
       58 . The borehole network as claimed in  claim 57 , further comprising a power source located at the intermediate surface location, for providing electrical power to the electrical submersible pump.  
   
   
       59 . The borehole network as claimed in  claim 57 , further comprising a power source located at one of the first end surface location or the second end surface location, for providing electrical power to the electrical submersible pump.  
   
   
       60 . The borehole network as claimed in  claim 53 , further comprising a pump located in one of the pair of lateral boreholes, for pumping a fluid through the subterranean path.  
   
   
       61 . The borehole network as claimed in  claim 60  wherein the pump is an electrical submersible pump.  
   
   
       62 . The borehole network as claimed in  claim 61 , further comprising a power source located at the intermediate surface location, for providing electrical power to the electrical submersible pump.  
   
   
       63 . The borehole network as claimed in  claim 61 , further comprising a power source located at one of the first end surface location or the second end surface location, for providing electrical power to the electrical submersible pump.  
   
   
       64 . The borehole network as claimed in  claim 48 , further comprising a surface installation associated with the first end surface location, for transferring a fluid to the borehole network.  
   
   
       65 . The borehole network as claimed in  claim 48 , further comprising a surface installation associated with the second end surface location, for receiving a fluid from the borehole network.  
   
   
       66 . The borehole network as claimed in  claim 48  wherein the intermediate surface location is located within a circular area defined by the first end surface location and the second end surface location.  
   
   
       67 . The borehole network as claimed in  claim 48  wherein the borehole network is comprised of a plurality of intermediate surface locations.  
   
   
       68 . The borehole network as claimed in  claim 67  wherein the intermediate surface locations are located within a circular area defined by the first end surface location and the second end surface location.