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.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a coiled tubing bottom hole assembly used to create an acid tunnel in a wellbore formation such that the tunnel is substantially transverse to the wellbore. Acid is pumped at a high pressure down the coiled tubing and out of a nozzle located on the end of a wand located at the end of the bottom hole assembly. The acid exits the nozzle and dissolves the formation creating a tunnel in the formation. The bottom hole assembly positions the nozzle so that the tunnel is substantially transverse to the wellbore. Multiple tunnels may be created in an attempt to increase the hydrocarbon production of the wellbore.

The bottom hole assembly also includes a first knuckle joint and a second knuckle joint to properly position the nozzle against the wellbore. The knuckle joints may be pressure operated and may increase the radius of curvature of the bottom hole assembly while providing a sufficient “attack” angle for the nozzle against the wellbore. The attack angle needs to be sufficient to promote the creation of a tunnel into the formation rather than eroding the exterior of the wellbore. The use of two knuckle joints may ensure a proper attack angle. The use of two knuckle joints may also reduce the chance that the wand will cam lock as it passes through a curved portion of the acid tunnel. The two knuckle joints may be oriented such that the two joints bend within the same plane, which may help the bottom hole assembly to stay within the same plane throughout the formation of the acid tunnel.

The wand may include a telescoping or extending portion to aid in the formation of a tunnel. The nozzle may also be adapted to form an acid tunnel that is oriented to help keep the bottom hole assembly within the same plane as it moves along and creates the entire length of the acid tunnel.

2. Description of the Related Art

It has become common to stimulate a wellbore in an effort to increase the production of hydrocarbons. One method to stimulate an openhole wellbore is to create an acid tunnel that is substantially transverse to the wellbore. Acid tunneling, also referred to as chemically-enhanced drilling, is a process that uses a nozzle attached to a bottom hole assembly that is run into the wellbore with coiled tubing. Once the nozzle is located at the desired location within the wellbore, acid is pumped down the coiled tubing at a high pressure. The high pressure acid exits the nozzle and dissolves the formation adjacent to the nozzle creating a tunnel. The tunnel may be created at a specified location of the wellbore to extend beyond a damaged or non-producing portion of the well.

The bottom hole assembly preferably includes a knuckle joint used to angle the nozzle towards the side of the wellbore. The nozzle is typically located on the end of a wand connected to the knuckle joint. The diameter of the wellbore as well as the geometric configuration of the wand, nozzle, and bottom hole assembly dictate the angle at which the knuckle joint can be bent within the wellbore. The rigidity of the bottom hole assembly causes the bottom hole assembly to have a fixed radius of curvature. The radius of curvature is dictated by the length of the wand, the angle that the knuckle joint bends, and the length of the assembly from the knuckle joint to the coiled tubing connection. These dimensions define a fixed radius through which the bottom hole assembly may travel.

It is generally desired to create an acid tunnel that is substantially transverse to the wellbore so that the tunnel extends beyond a damaged area of the wellbore. It is also important that the tunnel be substantially traverse because it may be desirable to create multiple tunnels within the wellbore. It is important that the attack angle of the nozzle be sufficient to create a tunnel that is substantially transverse to the wellbore. The knuckle of the bottom hole assembly needs to position the nozzle against the wellbore to ensure that the flow of acid out of the nozzle begins to form a tunnel. If the attack angle is too shallow, the high pressure acid may simply widen the bore of the wellbore rather than creating a tunnel transverse to the wellbore. To encourage the creation of a tunnel, the knuckle joint is often configured to have a maximum bend angle of approximately fifteen degrees away from the center of the bottom hole assembly. A fifteen degree bend angle typically allows knuckle to bend causing the nozzle located on the end of the wand to come into contact with the wellbore. Typically, the knuckle will not be bent to its maximum angle until after the tunnel has begun to form. The angle required for the knuckle to contact the wellbore can be decreased by increasing the length of the wand. However, increasing the length of the wand also increases the chance that the wand may become cam locked as it traverse the wellbore and the tunnel entrance.

The coiled tubing is used to push the bottom hole assembly and increase the length of the acid tunnel. The bottom hole assembly is rigid and as discussed above, the geometry of the bottom hole assembly (i.e. the bend angle of the knuckle joint, the length of the wand, and the length from the coiled tubing to the knuckle joint) defines the radius of curvature or “build rate” of the bottom hole assembly. The build rate of the bottom hole assembly determines the “build angle” of the tunnel (i.e. how quickly the tunnel turns so that it is transverse to wellbore). Often it may be desirable to create multiple tunnels in a single wellbore. Thus, it is important to have a build rate in the tunnel that is as high as practically possible, but not so high that it exceeds the yield strength of the coiled tubing that is connected to the tunneling bottom hole assembly. For example, in a 6 inch diameter wellbore, the current bottom hole assembly for acid tunneling typically has a theoretical build rate of 300 degrees per 100 feet of tunnel. This theoretical build rate exceeds the yield radius of curvature of typical coiled tubing. It would thus be beneficial to provide a bottom hole assembly that has a lower build rate, but that also may position the nozzle against the wellbore to ensure a tunnel transverse to the wellbore is created, but with a higher initial starting angle.

Current bottom hole assemblies have been use to create acid tunnels of up to fifty feet or more in length without damaging the coiled tubing. As discussed above, the theoretical build rate of the current bottom hole assembly exceeds the elastic limit of coiled tubing. In theory, if a fifty foot tunnel is created with the maximum build rate of the current acid tunneling bottom hole assembly, then the coiled tubing would exceed yield and the force required to push the tunneling bottom hole assembly along the tunnel would exceed the buckling strength of the unsupported coiled tubing in the borehole. However, there have been instances where a fifty foot tunnel has been created without appreciable damage to the coiled tubing. One explanation for this occurrence is that the bottom hole assembly may have titled or twisted out of its original plane while creating the tunnel while at the same time creating an elongated slot that allows the bottom hole assembly to slide downwards rather than turning a corner. The bottom hole assembly most likely twisted out of plane due to the forces exerted upon the bottom hole assembly as the build rate approaches the coiled tubing's yield radius of curvature. These forces likely cause the bottom hole assembly to twist off its plane affecting the direction and location of the acid tunnel.

The twisting or tilting of the bottom hole assembly out of its original plane may cause the acid tunnel to be formed in an area other than its intended location. For example, the tunnel may not extend through the very damaged or non-producing zone as originally intended. The rotation of the bottom hole assembly may also cause the tunnel to travel substantially parallel with the wellbore rather than substantially transverse limiting the number of tunnels that may be created as well as limiting the beneficial affects from the acid tunnel.

In light of the foregoing, it would be desirable to provide a bottom hole assembly that has a reduced build rate, but still create a tunnel that is substantially transverse to the wellbore. It would further be desirable to provide a bottom hole assembly with two knuckle joints to increase the overall radius of curvature of the bottom hole assembly above the yield radius of curvature of the coiled tubing. It would be desirable to orient the two knuckle joints such that the joints would bend in the same plane. It may also be desirable to provide a bottom hole assembly with an extendable or telescopic wand to aid in the formation of an acid tunnel. It would also be desirable to provide a nozzle adapted to form an acid tunnel that encourages the bottom hole assembly to remain in its original plane as the acid tunnel is created.

The present invention is directed to overcoming, or at least reducing the effects of, one or more of the issues set forth above.

SUMMARY OF THE INVENTION

The object of the present disclosure is to provide a bottom hole assembly having a larger radius of curvature than typical acid tunneling bottom hole assemblies with the bottom hole assembly still capable of creating an acid tunnel transverse to a wellbore. In one embodiment, an apparatus for creating an acid tunnel within a wellbore is disclosed. The apparatus includes a tool assembly having an upper end and a lower end, the tool assembly including an internal fluid passage. A coiled tubing connector connects the upper end of the tool assembly to coiled tubing. The coiled tubing is in fluid communication with the internal passage of the tool assembly.

The apparatus includes a first pressure operated knuckle joint connected to the lower end of the tool assembly. The first pressure operated knuckle joint includes a central bore that is in fluid communication with the internal passage of the tool assembly. The apparatus also includes a second pressure operated knuckle joint. The second pressure operated knuckle joint also includes a central bore that is in fluid communication with the central bore of the first pressure operated knuckle joint. The second pressure operated knuckle joint is located below the first knuckle joint. A member having a central fluid passage may connect the second pressure operated knuckle joint to the first pressure operated knuckle joint.

The apparatus further includes a wand having a first end, a second end, and a central bore. The first end of the wand is connected to the bottom of the second pressure operated knuckle joint. The central bore of the wand is in fluid communication with the central bore of the second pressure operated knuckle joint. A nozzle is connected to the second end of the wand. The nozzle being in fluid communication with the coiled tubing through the tool assembly, first knuckle joint, second knuckle joint, and the wand. Alternatively, a wand having at least one external port may be used in place of the disclosed nozzle and wand configuration as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. Alternatively, the wand of the bottom hole assembly may be telescopic allowing the end of the wand to extend as the bottom hole assembly creates the acid tunnel.

The first pressure operated knuckle joint and the second pressure operated knuckle joint of the apparatus may be adapted to bend within the same plane. The use of two knuckle joints may provide that the radius of curvature of the apparatus be greater than the yield radius of curvature of coiled tubing. The apparatus of claim 2, wherein the maximum angle that first pressure operated knuckle joint and the second pressure operated knuckle joint may each bend is less than approximately ten degrees.

In another embodiment, a coiled tubing bottom hole assembly for acid tunneling in a wellbore the bottom hole assembly is disclosed. The bottom hole assembly includes a coiled tubing connector that connects the bottom hole assembly to coiled tubing. A nozzle is connected to the lower end of the coiled tubing bottom hole assembly and a first knuckle joint is connected above the nozzle. The first knuckle joint includes a bore that is in fluid communication with the nozzle. The bottom hole assembly includes a second knuckle joint connected to the bottom hole assembly. The second knuckle joint includes a bore and is positioned above the first knuckle joint and below the coiled tubing connector. The nozzle is in fluid communication with the coiled tubing through the bottom hole assembly, the second knuckle joint, and the first knuckle joint.

The knuckle joints may be pressure operated. The knuckle joints may be various non-torque bearing or torque bearing joints and may be actuated by various means as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. The knuckle joints may be adapted to bend to a specific degree. The knuckle joints may be limited to bending less than approximately ten degrees from center. Preferably, the first and second knuckle joints are configured to bend collectively less than approximately fifteen degrees. The first knuckle joint and the second knuckle joint are preferably oriented to bend within substantially the same plane. This orientation may help to prevent the twisting of the bottom hole assembly off of its original build plane as it forms a tunnel.

The bottom hole assembly may further include a wand having a central bore, a first end, and a second end. The first end of the wand may be collected to the first knuckle with the second end of the wand being connected to the nozzle. The wand may include a telescoping or extending section that aids in the formation of the tunnel. The nozzle of the bottom hole assembly may includes a plurality of ports in an asymmetrical pattern. The asymmetrical pattern may be adapted to form an elliptical hole in a wellbore formation. Alternatively, the nozzle may include a plurality of ports in a symmetrical pattern with a plurality of flow channels in an asymmetrical pattern adapted to form an elliptical hole in the wellbore formation.

One embodiment of the invention is an apparatus used to create a transverse acid tunnel in a wellbore. The apparatus includes a bottom hole assembly that has an upper end and a lower end. The upper end of the assembly is connected to coiled tubing and the assembly further includes a fluid path through the assembly that is in communication with the coiled tubing. The apparatus also includes a means for jetting acid into the wellbore. The means for jetting acid is connected to the lower end of the bottom hole assembly and is in fluid communication with the coiled tubing through the bottom hole assembly. The bottom hole assembly further includes a first means for selectively bending the means for jetting acid towards the wellbore and a second means for selectively bending the means for jetting acid towards the wellbore.

The apparatus may also include means for extending the means for jetting acid away from the bottom hole assembly. Additionally, the first means for selectively bending may be adapted to bend in the same plane as the second means for selectively bending. The radius of curvature of the bottom hole assembly may be greater than the yield radius of curvature of coiled tubing due to the first means for selectively bending and the second means for selectively bending.

One embodiment of the invention is a method of creating an acid tunnel within a Wellbore. The method includes connecting a bottom hole assembly to coiled tubing and Positioning the bottom hole assembly at a desired location within the wellbore. The bottom hole assembly includes a first knuckle joint, a second knuckle joint, and a nozzle with the nozzle being located at the bottom end of the bottom hole assembly. The method further includes actuating the first knuckle joint to move the nozzle towards the wellbore and actuating a second knuckle of the bottom hole assembly so that the nozzle is substantially in contact with the wellbore method also includes pumping acid down coiled tubing and jetting the acid out of the nozzle to create an acid tunnel that is substantially transverse to the wellbore.

The method may also include extending the nozzle towards the acid tunnel. The nozzle may be extended by a telescopic section of a wand. The method may also include orienting the first knuckle joint and the second knuckle joint so that both knuckle joints bend within substantially the same plane. The method may include limiting the collective bend angle for both knuckle joints to less than approximately fifteen degrees. Alternatively, the method may include limiting the bend angle of the first knuckle joint to less than approximately ten degrees and limiting the bend angle of the second knuckle joint to less than approximately ten degrees.

The method may include the steps of pushing the coiled tubing to create a longer acid tunnel and pulling up the coiled tubing once the acid tunnel is a desired length. After the coiled tubing has been pulled up the method may include locating the nozzle at a different location within the wellbore. After being positioned at a different location, the method may include pumping acid down the coiled tubing and jetting acid out of the nozzle to create a second acid tunnel that is substantially transverse to the wellbore.

The method may include using a rotary indexing device in the top portion of the acid tunneling BHA to position the nozzle in a direction away from the previously formed tunnel to ensure that tunnels are spaced more effectively around the circumference of the wellbore.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a current bottom hole assembly used to create an acid tunnel off a wellbore, the assembly having a single pressure elbow that moves a nozzle into contact with the

FIG. 2 shows the bottom hole assembly of FIG. 1 starting to create a tunnel in

FIG. 3 shows one embodiment of a bottom hole assembly that may be used to create an acid tunnel off a wellbore, the bottom hole assembly including two knuckle joints to increase the radius of curvature of the bottom hole assembly while providing that the tunnel is substantially transverse to the wellbore.

FIG. 4 shows the bottom hole assembly of FIG. 3 starting to create a tunnel that is substantially transverse to the wellbore.

FIG. 5 is the end view of one embodiment of a nozzle having fluid ports in a symmetrical pattern with flow channels in an asymmetrical pattern adapted to form an elliptical hole in a wellbore formation.

FIG. 6 is the side view of the nozzle having flow channels in an asymmetrical in FIG. 5.

While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Illustrative embodiments of the invention are described below as they might be employed in a bottom hole assembly having a radius of curvature that is greater than the yield radius of curvature of coiled tubing and that may be used to produce an acid tunnel transverse to a wellbore. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

Further aspects and advantages of the various embodiments of the invention will become apparent from consideration of the following description and drawings.

FIG. 1 shows the configuration of a typical bottom hole assembly 100 that is used to create an acid tunnel 30 (shown in FIG. 2) within the formation 20 such that the tunnel 30 is substantially transverse to the wellbore 10. The bottom hole assembly 100 is connected to coiled tubing 5 by a coiled tubing connector 110. At the lower end of the bottom hole assembly 100 is a pressure elbow 150 that is actuated to move a wand 160 and nozzle 170 towards the wellbore 10. The bottom hole assembly 100 may include various components such as a check valve 120 and hydraulic disconnect 130 as would be appreciated by one of ordinary skill in the art.

Acid is pumped at a high pressure down the coiled tubing and through the bottom hole assembly 100 until the acid exits the nozzle 170. The back pressure from the nozzle causes the pressure elbow 150 to be actuated positioning the nozzle 170 against the wellbore. At this position, the acid exiting the nozzle begins to dissolve the formation 20 creating a tunnel 30 as shown in FIG. 2. The coil tubing is then lowered into the wellbore 10 advancing the formation of the tunnel 30 through the formation 20. As the tunnel 30 is created the bottom hole assembly 100 advances into the tunnel 30. However, the geometry of the bottom hole assembly 100 dictates the radius through which the bottom hole assembly 100 may travel. Specifically, the distance from the nozzle 170 to the pressure elbow 150, the angle of the pressure elbow 150, and the distance from the pressure elbow 150 to the coiled tubing connector 110 determines the radius through which the bottom hole assembly 100 may travel.

With the configuration shown in FIG. 1, the pressure elbow 150 generally is actuated to an initial kickover angle θ from the centerline of the bottom hole assembly 100 to ensure that the nozzle 170 comes into contact with the wellbore 10. This is done to ensure that the acid begins to create a tunnel into the side of the wellbore 10. The geometry of the bottom hole assembly 100 as well as the wellbore 10 dictates the initial kickover angle θ required to have the nozzle 170 contact the side of the wellbore 10 as illustrated by the following formula whereas l is the length of the wand 160, D is the diameter of the wellbore 10, and d is diameter of the bottom hole assembly 100.

l sin θ>D−d/2

The above formula illustrates that in order to have the nozzle 170 touch the side of the wellbore 10 the length I of the wand multiplied the sine of the angle θ must be greater than the diameter D of the wellbore minus ½ of the diameter d of the bottom hole assembly. Thus, increasing the wand length decreases the angle θ necessary to touch the wellbore. As discussed above, increasing the length of the wand 160 increases the chance that the bottom hole assembly 100 may become cam locked within the tunnel 30. However, increasing the initial kickover angle θ also decreases the radius of curvature such that the radius of curvature of the bottom hole assembly 100 may be smaller than the yield radius of the coiled tubing 5.

Once the tunnel is begun, the pressure elbow 150 is bent to its maximum kickover angle θ to increase the build angle of the tunnel as shown in FIG. 2. Typically the maximum kickover angle θ is less than fifteen degrees. This current configuration of the bottom hole assembly creates a radius of curvature of the bottom hole assembly 100 that is smaller than the yield radius of curvature of coiled tubing which may cause unacceptable forces on the coiled tubing as it creates a tunnel 30. The length of the wand 160 may be increased in an effort to decrease the kickover angle θ required to touch the wellbore with the nozzle 170. However, increasing the length of the wand 160 also increases the chance that the bottom hole assembly 100 will become cam locked within the tunnel 30. For at least these reasons, it may be beneficial to provide a new configuration that may overcome these potential issues.

FIG. 3 shows the configuration of one embodiment of a bottom hole assembly 100 that includes a first knuckle joint 155 and a second knuckle joint 156 used to create an acid tunnel 30 within the formation 20 so that the tunnel 30 is substantially transverse to the wellbore 10. The two knuckle joints 155, 156 are actuated to touch the nozzle 170 to the side of the wellbore 10 and permits the use of a shorter wand 160 than the prior configuration. The two knuckle joints 155, 156 increases the radius of curvature of the bottom hole assembly 100 while increasing the attack angle of the nozzle 170 to the wellbore 10.

Acid may be pumped at a high pressure down the coiled tubing and through the bottom hole assembly 100 until the acid exits the nozzle 170. With the nozzle 170 positioned against the wellbore 10, the acid exiting the nozzle 170 begins to dissolve the formation 20 and create a tunnel 30 as shown in FIG. 4. The coiled tubing may be lowered into the wellbore 10 advancing the formation of the tunnel 30 through the formation 20. As the tunnel 30 is created the bottom hole assembly 100 advances into the tunnel 30. The use of two knuckle joints 155, 156 provides that the tunnel 30 will be substantially transverse to the wellbore by increasing the starting angle of the tunnel, but without increasing the build angle of the tunnel.

The use of two knuckles 155, 156 increases the lateral displacement of the nozzle 170 with a smaller initial kickover angle θ₁, θ₂ for each knuckle. Assuming that the length 1 of the wand 160 is equal to the length between the first knuckle 155 and the second knuckle 156 and that the initial kickover angle θ₁ for the first knuckle 155 is equal to the kickover angle θ₂ for the second knuckle 156, the following equation may be used to determine the minimum kickover angle θ required for the nozzle 170 to touch the wall of the wellbore 10.

l(sin θ+sin 2θ)>D−d/2

The above formula illustrates that a smaller initial kickover angle is required to touch the nozzle 170 to the wall of the wellbore 10 when the bottom hole assembly 100 includes two knuckle joints 155, 156. The use of two knuckle joints provides that a smaller maximum kickover angle may be used for each knuckle joint without sacrificing a quick build angle for the tunnel. The use of two knuckle joints also permits a smaller maximum kickover angle may be used to create a tunnel substantially transverse to the wellbore. The use of smaller maximum kickover angles may be used to increase the radius of curvature of the bottom hole assembly above the yield radius of curvature of coiled tubing while still providing a sufficient attack angle and build angle.

FIGS. 5 and 6 show one embodiment of a nozzle 170 that has been adapted to promote the formation of an elliptical hole in a wellbore formation. The nozzle 170 includes fluid ports 173 that may be angled, as shown in FIG. 5, to promote the creation of an elliptical shaped hole. The nozzle 170 also includes a central fluid port 174. The nozzle 170 includes a plurality of grooves or flow channels 171, 172 on the exterior of the nozzle 170 that provide a pathway for the acid to flow past the nozzle after it has been jetted against the wellbore formation. The size and placement of the grooves may be configured in an asymmetrical pattern to promote the formation of an elliptical hole by the nozzle 170. For example, one set of grooves 172 may have a larger passage area that another set of grooves 171 allowing more acid to pass along the exterior of the nozzle 170. Portions of the wellbore may be dissolved faster than the rest of the wellbore due to a longer duration of exposure to the acid. The differences in acid flow along the nozzle may be used to promote the formation of an elliptical hole in the wellbore. As would be appreciated by one of ordinary skill the art having the benefit of this disclosure, the configuration and sizes of the exterior flow paths may be varied within the spirit of this invention.

Although various embodiments have been shown and described, the invention is not so limited and will be understood to include all such modifications and variations as would be apparent to one skilled in the art.

Claims

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.