Acid tunneling bottom hole assembly

Abstract

A bottom hole assembly connected to coiled tubing to create an acid tunnel in a wellbore formation. High pressure acid is pumped down the coiled tubing and out a nozzle located at the end of the bottom hole assembly. The bottom hole assembly includes a first knuckle joint and a second knuckle joint to properly position the nozzle against the wellbore. The two knuckle joints increases the radius of curvature of the bottom hole assembly while providing a sufficient attack angle for the nozzle against the wellbore. The two knuckle joints also may reduce the chance that the nozzle will cam lock within the acid tunnel. The two knuckle joints may be oriented such that they bend within the same plane. The nozzle may be connected onto the end of wand having a telescoping portion. The nozzle may be adapted to form an elliptical acid tunnel.

1 . An apparatus for acid tunneling within a wellbore, the apparatus comprising:
 a tool assembly having an upper end and a lower end, the tool assembly including an internal fluid passage;   a coiled tubing connector, the coiled tubing connector connecting the upper end of the tool assembly to coiled tubing, wherein the coiled tubing is in fluid communication with the internal passage of the tool assembly;   a first pressure operated knuckle joint connected to the lower end of the tool assembly, the first pressure operated knuckle joint having a central bore in fluid communication with internal passage of the tool assembly;   a second pressure operated knuckle joint, the second pressure operated knuckle joint having a central bore in communication with the central bore of the first pressure operated knuckle joint, the second pressure operated knuckle joint being connected below the first knuckle joint;   a wand having a first end, a second end, and a central bore, the first end of the wand being connected below the second pressure operated knuckle joint, wherein the central bore of the wand is in fluid communication with the central bore of the second pressure operated knuckle joint; and   a nozzle connected to the second end of the wand, wherein the nozzle is in fluid communication with the coiled tubing.   
   
   
       2 . The apparatus of  claim 1 , wherein the wand is telescopic. 
   
   
       3 . The apparatus of  claim 1 , wherein the first pressure operated knuckle joint and the second pressure operated knuckle joint are adapted to bend in the same plane. 
   
   
       4 . The apparatus of  claim 3 , wherein the radius of curvature of the apparatus is more than the yield radius of curvature of coiled tubing. 
   
   
       5 . The apparatus of  claim 3 , wherein the maximum angle that first pressure operated knuckle joint and the second pressure operated knuckle joint may each bend is less than about ten degrees. 
   
   
       6 . A coiled tubing bottom hole assembly for acid tunneling in a wellbore the bottom hole assembly comprising:
 a coiled tubing connector, the coiled tubing connector connecting the bottom hole assembly to coiled tubing;   a nozzle connected to the lower end of the coiled tubing bottom hole assembly;   a first knuckle joint, the first knuckle joint having a bore and being connected to the bottom hole assembly above the nozzle; and   a second knuckle joint, the second knuckle joint having a bore and being connected to the bottom hole assembly above the first knuckle joint and below the coiled tubing connector;   wherein the nozzle is in communication with the coiled tubing.   
   
   
       7 . The bottom hole assembly of  claim 6 , wherein the first knuckle joint is pressure operated. 
   
   
       8 . The bottom hole assembly of  claim 7 , wherein the maximum angle the first knuckle joint may bend is less than about ten degrees. 
   
   
       9 . The bottom hole assembly of  claim 6 , wherein the second knuckle joint is pressure operated. 
   
   
       10 . The bottom hole assembly of  claim 9 , wherein the maximum angle the second knuckle joint may bend is less than about ten degrees. 
   
   
       11 . The bottom hole assembly of  claim 6 , wherein the first and second knuckle joints are pressure operated and may bend up to approximately fifteen degrees collectively. 
   
   
       12 . The bottom hole assembly of  claim 6  further comprising a wand having a central bore, a first end, and a second end, wherein the first end of the wand is connected below the first knuckle joint and the nozzle is connected to the second end of the wand. 
   
   
       13 . The bottom hole assembly of  claim 12  wherein the wand includes a telescoping section. 
   
   
       14 . The bottom hole assembly of  claim 6  wherein the first knuckle joint and the second knuckle joint are adapted to bend in substantially the same plane. 
   
   
       15 . The bottom hole assembly of  claim 6  wherein the nozzle includes a plurality of ports in an asymmetrical pattern. 
   
   
       16 . The bottom hole assembly of  claim 15  wherein the asymmetrical pattern is adapted to form an elliptical hole in a wellbore formation. 
   
   
       17 . The bottom hole assembly of  claim 6  wherein the nozzle includes a plurality of ports in a symmetrical pattern and a plurality of flow channels in an asymmetrical pattern. 
   
   
       18 . A coiled tubing bottom hole assembly for acid tunneling in a wellbore the bottom hole assembly comprising:
 a coiled tubing connector, the coiled tubing connector connecting the bottom hole assembly to coiled tubing;   a wand connected to the lower end of the coiled tubing bottom hole assembly, wherein the wand includes a central bore and at least exterior port;   a first knuckle joint, the first knuckle joint having a bore and being connected to the bottom hole assembly above the wand; and   a second knuckle joint, the second knuckle joint having a bore and being connected to the bottom hole assembly above the first knuckle joint and below the coiled tubing connector;   wherein the central bore of the wand is in communication with the coiled tubing.   
   
   
       19 . The bottom hole assembly of  claim 18  wherein the first knuckle joint and the second knuckle joint are pressure operated. 
   
   
       20 . The bottom hole assembly of  claim 19  wherein the maximum angle the first knuckle joint may bend is less than about ten degrees and the maximum angle the second knuckle joint may bend is less than about ten degrees. 
   
   
       21 . The bottom hole assembly of  claim 19  wherein the first and second knuckle joints may bend up to approximately fifteen degrees collectively. 
   
   
       22 . The bottom hole assembly of  claim 18  wherein the first knuckle joint and the second knuckle joint are adapted to bend in substantially the same plane. 
   
   
       23 . An apparatus used to create an acid tunnel in a wellbore, the apparatus comprising
 a bottom hole assembly having an upper end and a lower end, the assembly including a fluid path through the assembly, wherein the upper end of the assembly is connected to coiled tubing;   a means for jetting acid into the wellbore, wherein the means for jetting acid is in fluid communication with the coiled tubing and the means for jetting acid is connected to the lower end of the bottom hole assembly;   wherein the bottom hole assembly includes a first means for selectively bending the means for jetting acid towards the wellbore; and   wherein the bottom hole assembly includes a second means for selectively bending the means for jetting acid towards the wellbore.   
   
   
       24 . The apparatus of  claim 23  further comprising means for extending the means for jetting acid away from the bottom hole assembly. 
   
   
       25 . The apparatus of  claim 23  wherein the first means for selectively bending is adapted to bend in the same plane as the second means for selectively bending. 
   
   
       26 . The apparatus of  claim 23  wherein the radius of curvature of the apparatus is more than the yield radius of curvature of coiled tubing. 
   
   
       27 . A method of creating an acid tunnel within a wellbore, the method comprising:
 connecting a bottom hole assembly to coiled tubing, the bottom hole assembly including a first knuckle joint, a second knuckle joint, and a nozzle located at the bottom of the bottom hole assembly;   positioning the bottom hole assembly at a desired location within the wellbore;   actuating the first knuckle joint, wherein the nozzle moves towards the wellbore;   actuating a second knuckle of the bottom hole assembly, wherein the nozzle is substantially in contact with the wellbore;   pumping acid down coiled tubing;   jetting acid out of the nozzle, wherein the acid creates an acid tunnel substantially transverse to the wellbore.   
   
   
       28 . The method of  claim 27  further comprising extending the nozzle towards the acid tunnel. 
   
   
       29 . The method of  claim 27  further comprising orienting the first knuckle joint and the second knuckle joint such that the knuckle joints bend on substantially the same plane. 
   
   
       30 . The method of  claim 27  further comprising limiting the collective bend angle for both knuckle joints to less than approximately fifteen degrees. 
   
   
       31 . The method of  claim 27  further comprising limiting the bend angle of the first knuckle joint to less than about ten degrees. 
   
   
       32 . The method of  claim 31  further comprising limiting the bend angle of the second knuckle joint to less than about ten degrees. 
   
   
       33 . The method of  claim 27  further comprising pushing the coiled tubing to create a longer acid tunnel. 
   
   
       34 . The method of  claim 33  further comprising pulling up the coiled tubing once the acid tunnel is a desired length. 
   
   
       35 . The method of  claim 34  further comprising locating the nozzle at a different location in the wellbore. 
   
   
       36 . The method of  claim 35  further comprising pumping acid down the coiled tubing and jetting acid out of the nozzle, wherein the acid creates a second acid tunnel substantially transverse to the wellbore. 
   
   
       37 . A method of creating an acid tunnel within a wellbore, the method comprising:
 connecting a bottom hole assembly to coiled tubing, the bottom hole assembly including a first knuckle joint, a second knuckle joint, and a wand located at the bottom of the bottom hole assembly, wherein the wand has a central bore in communication with the coiled tubing and at least one external port in communication with the central bore;   positioning the bottom hole assembly at a desired location within the wellbore;   actuating the first knuckle joint, wherein the wand moves towards the wellbore;   actuating a second knuckle of the bottom hole assembly, wherein the at least one external port of the wand is substantially in contact with the wellbore;   pumping acid down coiled tubing;   jetting acid out of the at least one external port of the wand, wherein the acid creates an acid tunnel substantially transverse to the wellbore.   
   
   
       38 . The method of  claim 37  further comprising extending the wand towards the acid tunnel. 
   
   
       39 . The method of  claim 37  further comprising orienting the first knuckle joint and the second knuckle joint such that the knuckle joints bend on substantially the same plane.