US20170191344A1

US20170191344A1 - Method of installing deep anode cathodic protection system including one-piece coiled vent pipe

Info

Publication number: US20170191344A1
Application number: US15/461,790
Authority: US
Inventors: Glenn Wright Shreffler, III; William R. Schutt
Original assignee: Matcor Inc
Current assignee: Matcor Inc
Priority date: 2014-08-26
Filing date: 2017-03-17
Publication date: 2017-07-06
Also published as: US20160060766A1

Abstract

A method of deploying a deep anode in a cathodic protection system including an anode assembly, a one-piece vent pipe assembly and a reel is disclosed. The anode assembly includes elongated anode. The vent pipe assembly includes a tube having a distal end and an apertured portion having an array of holes in it. A fabric sleeve extends about the apertured portion. The tube, the sleeve and the anode assembly are coiled up on a reel and uncoiled therefrom for extension into the bore hole. The holes in the tube enable gases to vent from the bore hole through the tube. The tube has a predetermined nominal internal diameter sufficient to enable a viscous settable material to be pumped into the tube to seal its interior when it is no longer desired to vent gases.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 14/468,899, filed on Aug. 26, 2014, entitled System Including One-Piece Coiled Vent Pipe For Deep Anode Cathodic Protection And Method Of Installing The Same, which is assigned to the same assignee as this application and whose disclosure is incorporated by reference herein in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

“Not Applicable”

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK

“Not Applicable”

FIELD OF THE INVENTION

This invention relates generally to cathodic protection systems and more particularly to systems including anode assemblies and associated one-piece vent pipe assemblies for deep bore hole installations and methods of installing deep anode cathodic protections systems.

BACKGROUND OF THE INVENTION

The protection of oil and gas pipelines from corrosion is commonly achieved by means of a deep anode assembly which is deployed into a deep bore hole adjacent the structure to be protected. The bore hole may extend several hundred feet into the earth. The anode assembly typically used in such a system includes a packaged linear anode which may be either a polymeric cable anode or a Mixed Metal Oxide (MMO) wire anode. One particularly useful elongated linear anode is commercially available from Matcor, Inc., the assignee of the subject invention, under the DURAMMO™ trademark.
Gases are produced by the operation of an anode assembly in the catholic protection system, i.e., when the anode passes DC current through the electrolyte and water in the bore hole, hydrogen, chlorine, oxygen, etc. are produced. Those gases should be vented out of the bore hole. Otherwise the gases could interfere with the performance of the anode assembly and cause damage to the cable of the system. To that end, it is a common practice to make use of an elongated vent pipe in the bore hole. In particular, a vent pipe is extended into the bore hole from top of the bore hole to a point closely adjacent its bottom and alongside the linear anode. The vent pipe includes a plurality of holes or apertures along at least a substantial portion of its length, e.g., the portion alongside the linear anode, through which gases produced by the operation of the anode can be vented to the surface. Heretofore such vent pipes have been in the form of plural linear rigid sections which are introduced sequentially into the bore hole, with the trailing end of the prior linear section being secured to the leading end of the next successive linear section. Obviously, this method of deployment is time consuming, complicated and relatively expensive. To simplify the installation process, the vent pipe may be in the form of a continuous pipe that is wound up on a reel and then uncoiled for extension into the bore hole. Matcor, Inc. has been installing coiled vent pipes under the trademark SUPERVENT for some time. The SUPERVENT™ coiled vent pipe makes use of a fabric sleeve extending about the pipe at the location of its holes. The fabric sleeve serves to enable gases to pass through it and through the holes into the interior of the pipe, while preventing coke breeze or other conductive materials located within the bore hole from gaining ingress into the interior of the pipe. The SUPERVENT™ coiled vent pipe must be small, e.g., less than 1.5″ nominal internal diameter, to enable it to be wound up on a reel.
Irrespective of the manner in which the vent pipe is deployed into the deep bore hole, since it has apertures or holes extending along a substantial length thereof, there is the potential that water from aquifers in the ground at various levels to mix by gaining access to the vent pipe. For example, water from one aquifer at a level A could mix with water at an aquifer at a level B by gaining ingress through the apertures of the vent pipe at the level A and flowing through the vent pipe to the apertures at the level B. Thus, some states, e.g., California, have enacted legislation requiring the sealing of deep bore hole vent pipes after use of the anode assembly to which they are coupled is no longer required. Such sealing can be accomplished by pumping concrete into the vent pipe. However, in order to effectively pump concrete into the vent pipe, particularly one that extends several hundred feet into the ground, requires a vent pipe of larger internal diameter than the prior art 1.5″ SUPERVENT™ coiled vent pipe. In particular, the vent pipe should be of a nominal internal diameter of at least 2 inches.
Accordingly, a need exists for a one-piece vent pipe which can be wound up on a reel and unwound readily therefrom for extension into a deep bore hole and which is of sufficiently large internal diameter to enable concrete or other viscous sealing material to be pumped therein when desired. The subject invention addresses that need and also provides a means and a method for effectively and efficiently carrying an associated elongated anode assembly into the bore hole for deployment.
All references cited and/or identified herein are specifically incorporated by reference herein.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention there is provided a one-piece vent pipe assembly for use in a cathodic protection system having an elongated anode assembly located in a deep bore hole in the earth. The anode assembly extends along a substantial distance adjacent the bottom of the bore hole. The vent pipe assembly comprises a tube, a fabric sleeve and a reel. The tube is formed of a plastic material and has a distal end and an apertured portion located adjacent the distal end. The tube includes an array of holes in the apertured portion of the tube. The fabric sleeve extends about the apertured portion of the tube. The tube and fabric sleeve are coiled up on the reel, but arranged to be uncoiled therefrom for extension into the bore hole, whereupon the apertured portion of the tube is located in a bottom portion of the bore hole and extending alongside the elongated anode assembly. The holes in the tube enable gases produced by the operation of the anode assembly to gain ingress from the bore hole through the fabric sleeve into the interior of the tube to be vented from the tube. The tube has a predetermined nominal internal diameter sufficient to enable a viscous settable material, e.g., concrete, to be pumped into the tube to seal the interior thereof when the tube is no longer desired to vent gases produced by the operation of the anode assembly.
In accordance with another aspect of this invention a system including an anode assembly and one-piece vent pipe assembly is provided for use in a cathodic protection system. The anode assembly comprises an elongated anode and a pair of cables connected to respective end portions of the anode. The anode assembly is arranged to be located in a deep bore hole in the earth, whereupon the elongated anode extends along a substantial distance adjacent the bottom of the bore hole. The vent pipe assembly comprises a tube, a fabric sleeve and a reel. The tube is formed of a plastic material and has a distal end and an apertured portion located adjacent the distal end. The tube includes an array of holes in the apertured portion of the tube. The fabric sleeve extends about the apertured portion of the tube. The tube, the fabric sleeve and the anode assembly are coiled up on the reel, but arranged to be uncoiled therefrom for extension into the bore hole, whereupon the apertured portion of the tube is located in a bottom portion of the bore hole and extending alongside the elongated anode assembly. The holes in the tube enable gases produced by the operation of the anode assembly to gain ingress from the bore hole through the fabric sleeve into the interior of the tube to be vented from the tube. The tube has a predetermined nominal internal diameter sufficient to enable a viscous settable material to be pumped into the tube to seal the interior thereof when the tube is no longer desired to vent gases produced by the operation of the anode assembly.
In accordance with another aspect of this invention there is provided a method of installing a system including an anode assembly and a one-piece vent pipe assembly into a deep bore hole in the earth. The anode assembly comprises an elongated anode and a pair of cables connected to respective end portions of the anode. The vent pipe assembly comprises a tube, a fabric sleeve and a reel. The tube is formed of a plastic material and has a distal end and an apertured portion located adjacent the distal end. The tube has a predetermined nominal interval diameter sufficient to enable a viscous settable material to be pumped into the tube to seal the interior thereof. The tube includes an array of holes in the apertured portion of the tube. The fabric sleeve extends about the apertured portion of the tube. The tube, the fabric sleeve and the anode assembly are coiled up on the reel. The method basically entails providing a weight on the distal end of the tube and introducing the distal end of the tube into the bore hole, whereupon the tube, the fabric sleeve and the anode assembly are uncoiled from the reel and extend into the bore hole, with the apertured portion of the tube located in a bottom portion of the bore hole, the elongated anode assembly extending along the aperture portion of the tube and the cables extending upward through the bore hole.
A further aspect of the method of this invention entails coupling the cables to a cathodic protection system to operate the anode assembly. The holes in the tube are arranged to enable gases produced by the operation of the anode assembly to gain ingress from the bore hole through the fabric sleeve into the interior of the tube to be vented from the tube.
One preferred aspect of the method of this invention entails drilling into the earth to form the bore hole and mixing coke breeze and water into a slurry and pumping the slurry via another pipe into the bore hole, whereupon the slurry surrounds the anode assembly, the apertured portion of the tube and the fabric sleeve.
Another preferred aspect of the method of this invention entails pumping a viscous settable material into the tube to seal the interior thereof when the tube is no longer desired to vent the gases from the tube, whereupon any water from aquifers at various levels in the ground contiguous with the bore hole will not be able to flow into the tube to mix together.

DESCRIPTION OF THE DRAWING

FIG. 1 is a side elevation view, partially in section, showing one exemplary embodiment of a system including a one-piece coiled vent pipe assembly and an elongated anode assembly constructed in accordance with this invention used in a deep bore hole to provide cathodic protection to an underground structure to be protected;

FIG. 2 is an enlarged view of a portion of the system shown in FIG. 1;

FIG. 3 is a side elevation view of a reel holding the one-piece coiled vent pipe forming a portion of the system shown in FIG. 1;

FIG. 4 is a front elevation view of the reel shown in FIG. 3;

FIG. 5 is a greatly enlarged side elevation view of the distal end portion of the one-piece coiled vent pipe and its associated fabric sleeve showing the pattern of the vent holes in the vent pipe;

FIG. 6 is a transverse cross-sectional view of the distal end portion of the vent pipe without the fabric sleeve thereon; and

FIG. 7 is a sectional view taken along line 7-7 of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the various figures of the drawing wherein like reference characters refer to like parts, there is shown at 20 in FIG. 1 one exemplary embodiment of a system constructed in accordance with the subject invention. The system basically comprises an anode assembly 22, a vent pipe assembly 24 and a reel 26. The system 20 is arranged to be deployed into a bore hole 10 extending deeply into the earth, to protect adjacent buried structures, such as gas or oil pipelines, etc. (not shown), from corrosion. The anode assembly 22 basically comprises an elongated anode 28 (FIG. 2) and associated lead cables 30 which are arranged to be electrically connected to a conventional cathodic protection system (not shown). When the system 20 is deployed so that the anode assembly 22 and the vent pipe assembly 24 are disposed within the bore hole 10, the bore hole is filled with a slurry 12 of coke breeze and water to surround the anode assembly and vent pipe assembly. The area of the bore hole in which the anode assembly is located is commonly referred to as the active area. The portion of the bore hole that is located above the anode assembly is commonly referred to as the inactive area and is filled with a Portland cement/Bentonite backfill 14 or some other suitable backfill material.
As best seen in FIG. 2, the elongated anode 28 is formed of elongated thin flexible member, e.g., a wire, a ribbon, a tube, etc., which is electrically conductive, e.g., is a noble metal combination, such as a mixed metal oxide (MMO) over titanium or platinum over niobium/copper, or any other conventional anode material(s), such as the heretofore DURAMMO™ anode sold by Matcor, Inc. The leading end of the anode 28 is electrically connected to one of the lead cables 30, while the trailing end of the anode is connected to the other of the lead cables. In accordance with a preferred embodiment of this invention both cables 30 are KYNAR™ POLY XL AWG #8 cables available from Matcor, Inc. The integrity of each anode-to-wire (cable) electrical connection is preferably achieved by means of a KYNEX® connection. The KYNEX® connection is the subject of U.S. Pat. No. 8,502,074 (Schutt), which is also assigned to Matcor, Inc. and whose disclosure is incorporated by reference herein. As mentioned above, the cables 30 are connected to a cathodic protection system (not shown).
The vent pipe assembly 24 basically comprises a unitary, one-piece pipe or tube 34 and a fabric sleeve 36. The tube 34 is formed of any suitable plastic material and has a nominal internal diameter of at least approximately 2 inches. One particularly effective plastic material is UV resistant SDR 13.5 Polyethylene (PE), with the tube having a wall thickness of approximately 0.176 inch. The tube 34 includes a distal end 38 and an apertured portion 40 located adjacent the distal end. The apertured portion 40 includes an array of holes 42 therein. The holes of the array serve as the means to enable gases produced by the operation of the anode assembly to pass therethrough into the interior of the vent pipe for passage through the vent pipe to the surface. The fabric sleeve 36 basically comprises a tube formed of any suitable fabric material, e.g., textured wide poplin polyester, and is disposed about the periphery of the apertured portion 40 of the vent pipe 24 to prevent the coke breeze from gaining ingress into the interior of the vent pipe, while enabling gases to enter into the vent pipe through the array of holes 42.
As best seen in FIGS. 5-7 the holes 42 making up the array are each of the same internal diameter. Moreover, they are of a size sufficient to provide flexibility to the apertured portion to enable the tube to be readily wound up on the reel 26. To that end, in accordance with one exemplary embodiment of this invention the array of holes comprises first pairs of holes 42A and second pairs of holes 42B, each of the holes of the first pairs 42A is located axially aligned along respective common axes 42C so that they are diametrically opposite each other at respective first positions along the length of the apertured portion 40 of the tube 34. Similarly, each of the holes of the second pairs 42B is located axially aligned along respective common axes 42D so that they are located diametrically opposite each other at respective second positions along the length of the apertured portion 40 of the tube 34. As best seen in FIGS. 2 and 5 the pairs of first holes 42A alternate with the pairs of the second holes 42B along the length of the apertured portion 40 of the tube 34. Moreover, as best seen in FIG. 6, the axis 42C is oriented perpendicularly to the axis 42D, whereupon the pairs 42A and 42B are disposed perpendicularly to each other.
In accordance with one exemplary preferred embodiment of the invention, the spacing between the first and second positions of the pairs of holes 42A and 42B is approximately 3 inches and each of the holes is approximately of 0.375 inch nominal internal diameter.
The deployment of the system 20 will now be described with reference to protecting an underground structure, e.g., an oil or gas pipeline (not shown). At the location of the structure to be protected a bore hole 10 is drilled into the earth. In accordance with one exemplary embodiment of the invention the bore hole is of a nominal internal diameter of 8 inches. The tube 34 with the fabric sleeve 36 on the distal end portion thereof, along with the anode assembly 24 is wound up on the reel 26 having a hub whose diameter is 45 inches is brought to the site of the bore hole. To that end that assembly is disposed on a shipping skid 44 (FIG. 3). A lowering rope 46 is also disposed on the shipping skid 44, along with a bottom weight 48. If desired, an additional bottom weight 50 may also be provided for deeper bore holes. At the site of the bore hole the reel 26 is removed from the skid and placed on a reel stand 32. The weight 48 can then be connected by any suitable means to the distal end 38 of the tube 34. The distal end of the lowering rope 46 is also connected to the distal end of the tube 34, e.g., tied to the weight 44 (as shown in FIG. 2). The weight 44 is then positioned over the top of the bore hole 10 while tension is maintained on the lowering rope 46 so that the weight 48, the vent tube 34 and the anode assembly 24 can be unwound together from the reel 26 and lowered into the bore hole. When the weight 48 has been lowered to the bottom of the bore hole, e.g., to the position shown in FIG. 1, the rope 46 is pulled tight and is tied off. Any excess tube 34, extending above the top of the bore hole can be removed, i.e., cut off, such as by means of a plastic tube cutter.
In accordance with one exemplary embodiment of this invention the active area of the bore hole is then filled with a coke backfill 12, e.g., Asbury 218L coke breeze (45 lbs/cubic foot) in the form of a slurry. The slurry is preferably pumped into the bore hole via another pipe, e.g., a 1″-2″ PVC stinger pipe (not shown) to fill the active area and completely surround the portion of the system 20 located in the active area. In the exemplary embodiment shown in FIG. 1, the active area into which the slurry is pumped is the lower 65′ of a 200′ deep exemplary bore hole 10.
The pumping operation should be continued uninterrupted until the active area is completely filled with the slurry 12. Once the coke breeze backfill has been deployed and has settled, the system 20 is ready for electrical hook-up to the cathodic protection system. The Portland cement/Bentonite fill 14 can then be introduced into the inactive area of the bore hole to complete the deployment and installation of the system.
The system 20 can then be operated for as long as required to protect the underground structure, e.g., the gas or oil pipeline, etc., from corrosion. When such action is no longer necessary or desired, the anode assembly can be disconnected from the cathodic protection system or otherwise de-energized. Cement or some other settable sealing material can then be pumped into the upper (cut-off) end of the tube 34 of the pipe assembly 24 to seal it, i.e., fill it and thus close off the holes 42. Once the vent pipe is sealed shut, water from aquifers at various levels in the ground contiguous with the bore hole will not be able to flow into the tube 34 to mix together, whereupon contamination of one aquifer will not result in contamination of another aquifer by virtue of mixing of their waters via the pipe assembly 24.
It should be noted that the exemplary embodiment of the system 20 and its method of deployment are merely exemplary. Thus, for example, the system may take other forms providing that it includes a one-piece vent tube which can be provided rolled up on a reel and which tube has a sufficiently large internal diameter to accommodate the pumping of a viscous sealing agent, such as but not limited to concrete, therein to seal it. Moreover, the method of deployment can entail other steps than those described above, e.g., while less desirable the anode assembly can be deployed into the bore hole separately from the deployment of the one-piece coiled vent pipe assembly.
Without further elaboration the foregoing will so fully illustrate our invention that others may, by applying current or future knowledge, adopt the same for use under various conditions of service.

Claims

We claim:

1. A method of installing an anode assembly and a one-piece vent pipe assembly into a deep bore hole in the earth, said anode assembly comprising an elongated anode and a pair of cables connected to respective end portions of said anode, said vent pipe assembly comprising a tube and a fabric sleeve, said tube being formed of a plastic material and having a distal end and an apertured portion located adjacent said distal end, said tube including an array of holes in said apertured portion of said tube, said tube having a predetermined nominal internal diameter sufficient to enable a viscous settable material to be pumped into said tube to seal the interior thereof, said fabric sleeve extending about said apertured portion of said tube, said method comprising

a) coiling said tube, said fabric sleeve and said anode assembly on a reel;

b) connecting a weight to said distal end of said tube;

c) introducing said distal end of said tube with said weight into said bore hole, whereupon said tube, said fabric sleeve and said anode assembly are uncoiled from said reel and extend into said bore hole with said apertured portion of said tube located in a bottom portion of said bore hole, with said elongated anode assembly extending along said aperture portion of said tube and with said cables extending upward through said bore hole; and

d) coupling said cables to a cathodic protection system to cause said anode assembly to operate, with said holes in said tube being arranged to enable gases produced by said operation of said anode assembly to gain ingress from the bore hole through said fabric sleeve into said interior of said tube to be vented from said tube.

2. The method of claim 1 additionally comprising:

e) attaching a rope to said weight and applying tension on said rope as said tube, said fabric sleeve and said anode assembly are uncoiled from said reel into said bore hole.

3. The method of claim 1 additionally comprising:

e) drilling into the earth to form said bore hole; and

f) mixing coke breeze and water into a slurry and pumping said slurry via another pipe into said bore hole, whereupon said slurry surrounds said anode assembly, said apertured portion of said tube and said fabric sleeve.

4. The method of claim 2 additionally comprising:

e) drilling into the earth to form said bore hole; and

5. The method of claim 1 wherein said bore hole extends through plural aquifers in the ground, said aquifers being at different levels.

6. The method of claim 5 additionally comprising:

e) pumping a viscous settable material into said tube to seal the interior thereof when said tube is no longer desired to vent the gases from said tube, whereupon any water from aquifers at various levels in the ground contiguous with the bore hole will not be able to flow into said tube to mix together.

7. The method of claim 6 wherein said settable material comprises concrete.

8. The method of claim 3 wherein said bore hole extends through plural aquifers in the ground, said aquifers being at different levels.

9. The method of claim 8 additionally comprising:

e) pumping a viscous settable material into said tube to seal the interior thereof when said tube is no longer desired to vent the gases from said tube, whereupon any water from aquifers at various levels in the ground contiguous with the bore hole will not be able to flow into said tube to mix together

10. The method of claim 9 wherein said settable material comprises concrete.

11. The method of claim 1 wherein said tube has a nominal internal diameter of 2.0 inches.

12. The method of claim 1 wherein said holes are of approximately 0.375 inch nominal internal diameter.

13. The method of claim 11 wherein said holes are of approximately 0.375 inch nominal internal diameter.

14. The method of claim 3 wherein said tube has a nominal internal diameter of 2.0 inches.

15. The method of claim 3 wherein said holes are of approximately 0.375 inch nominal internal diameter.

16. The method of claim 14 wherein said holes are of approximately 0.375 inch nominal internal diameter.

17. The method of claim 6 wherein said tube has a nominal internal diameter of 2.0 inches.

18. The method of claim 6 wherein said holes are of approximately 0.375 inch nominal internal diameter.

19. The method of claim 17 wherein said holes are of approximately 0.375 inch nominal internal diameter.