Modular downhole inspection system for coiled tubing

• US 5,485,745 A
• Filed: 09/01/1992
• Issued: 01/23/1996
• Est. Priority Date: 05/20/1991
• Status: Expired due to Term

• Current Assignee: Halliburton Company
• Original Assignee: Halliburton Company
• Inventors: Connell, Michael L., Olszewski, Walter K., Goiffon, John J., Rademaker, Robert A.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): BROCK, MICHAEL J
• Application Number:
  US07/938,622
• Time in Patent Office: 1,239 Days
• Field of Search: 73/151, 73/152, 385/90, 385/92, 385/94, 385/101, 385/107, 385/108, 340/854.7, 340/854.9, 340/855.1, 358/99, 358/100
• US Class Current: 73/152.39
• CPC Class Codes: E21B 17/203 with plural fluid passages
• CPC Class Codes: E21B 17/206 with conductors, e.g. electrical, optical
• CPC Class Codes: E21B 47/002 by visual inspection
• CPC Class Codes: E21B 47/135 using light waves, e.g. infrared or ultraviolet waves

Abstract

A downhole inspection tool is attached to the lower end of a length of coiled tubing having an electrical/fiberoptic cable threaded through the center. The coiled tubing carries a flow of optically clear and/or acoustically homogeneous fluid from a supply of such fluid at the surface. The tool itself includes a cable head subassembly module attached to the lower end of the coiled tubing and terminates the electrical and optical conductors within the cable. An inspection module for producing an electrical signal indicative of downhole conditions is detachably connected to the lower end of the cable head assembly module. An outer flow tube is mechanically connected to the inspection module and surrounds both of the modules to define an annular space therebetween. The flow tube has its upper end fluid coupled to the coiled tubing for conducting the flow of the optically clear and/or acoustically homogeneous fluid down along the annular space and out the lower end of the tool to create a region conducive to inspection by the tool.

Claims

1. A method of using a downhole inspection tool to inspect the interior of a borehole comprising:

providing a cable head subassembly module attached to the lower end of a length of coiled tubing having an electrical/fiberoptic cable threaded therethrough, said module including means for terminating the electrical and optical conductors within said cable and for mechanical and electrical connection to an inspection module capable of producing an electrical signal indicative of downhole conditions;

connecting an injector feed through boot protector to said the mechanical terminating means of said cable head subassembly module, said protector receiving therein said electrical terminating means of said subassembly module;

inserting said boot protector, cable head subassembly module and coiled tubing attached thereto through a coiled tubing injector;

removing said boot protector from said cable head subassembly module;

attaching an inspection module to said cable head subassembly module to produce a downhole inspection tool; and

running said tool downhole to inspect downhole conditions.

2. A method of using a downhole inspection tool to inspect the interior of a borehole as set forth in claim 1, wherein said injector feed through boot protector has a diameter approximately the same as that of said cable head subassembly module.

3. A method of using a downhole inspection tool to inspect the interior of a borehole as set forth in claim 1 which includes prior to the step of running said tool downhole the additional step of:

providing an outer flow tube having a diameter greater than both of said cable head subassembly module and said inspection module;

inserting said cable head subassembly module and said attached inspection module into said outer flow tube to define an annular space therebetween; and

fluid coupling the upper end of said outer flow tube to said coiled tubing for conducting a flow of optically clear and/or acoustically homogeneous fluid down along said annular space and out the lower end of said tool to create downhole a region conducive to inspection by said tool.

4. A method of using a downhole inspection tool to inspect the interior of a borehole as set forth in claim 3 wherein said fluid coupling step includes:

providing a crossover adapter within said cable head subassembly module for direct mechanical and fluid connection to the lower end of said coiled tubing, said adapter being closed at the bottom and including at least one port formed therein to allow the fluid flowing down said coiled tubing to pass to the outside of said adapter and into the annular region contained within said outer flow tube.

5. A method of using a downhole inspection tool to inspect the interior of a borehole as set forth in claim 3 includes the additional steps of:

mechanically connecting said outer flow tube to said inspection module; and

mechanically clamping said electrical/fiber optic cable within said cable head subassembly to prevent disturbance of the termination of the conductors thereof upon application of an upward force upon said coiled tubing to disconnect said subassembly from said inspection module and remove it from within said borehole in the event said outer flow tube becomes lodged downhole.

6. A system for using a downhole inspection tool to inspect the interior of a borehole as set forth in claim 3 wherein said fluid coupling means includes:

a crossover adapter within said cable head subassembly module for direct mechanical and fluid connection to the lower end of said coiled tubing, said adapter being closed at the bottom and including at least one port formed therein to allow the fluid flowing down said coiled tubing to pass to the outside of said adapter and into the annular region contained within said outer flow tube.

7. A system for using a downhole inspection tool to inspect the interior of a borehole as set forth in claim 3 which also includes:

means for mechanically connecting said outer flow tube to said inspection module; and

means for mechanically clamping said electrical/fiber optic cable within said cable head subassembly to prevent disturbance of terminations of the conductors thereof upon application of an upward force upon said coiled tubing to disconnect said subassembly from said inspection module and remove it from within said borehole in the event said outer flow tube becomes lodged downhole.

8. A system for using a downhole inspection tool to inspect the interior of a borehole comprising:

a cable head subassembly module attached to the lower end of a length of coiled tubing having an electrical/fiberoptic cable threaded therethrough, said module including means for terminating the electrical and optical conductors within said cable and for mechanical and electrical connection to an inspection module capable of producing an electrical signal indicative of downhole conditions;

means for connecting an injector feed through boot protector to said mechanical terminating means of said cable head subassembly module, said protector receiving therein said electrical terminating means of said subassembly module;

means for inserting said boot protector, cable head subassembly module and coiled tubing attached thereto through a coiled tubing injector;

means for removing said boot protector from said cable head subassembly module;

means for attaching an inspection module to said cable head subassembly module to produce a downhole inspection tool; and

means for running said tool downhole to inspect downhole conditions.

9. A system for using a downhole inspection tool to inspect the interior of a borehole as set forth in claim 8, wherein said injector feed through boot protector has a diameter approximately the same as that of said cable head subassembly module.

10. A system for using a downhole inspection tool to inspect the interior of a borehole as set forth in claim 8 which also includes:

an outer flow tube having a diameter greater than both of said cable head subassembly module and said inspection module;

means for inserting said cable head subassembly module and said attached inspection module into said outer flow tube to define an annular space therebetween; and

means for fluid coupling the upper end of said outer flow tube to said coiled tubing for conducting a flow of optically clear and/or acoustically homogeneous fluid down along said annular space and out the lower end of said tool to create downhole a region conducive to inspection by said tool.

11. A downhole inspection tool for attachment to the lower end of a length of coiled tubing having an electrical/fiberoptic cable threaded therethrough and carrying a flow of optically clear and/or acoustically homogeneous fluid from a supply of said fluid at the surface, said tool comprising:

a cable head subassembly module attached to the lower end of said coiled tubing and including means for terminating the electrical and optical conductors within said cable;

an inspection module for producing an electrical signal indicative of downhole conditions;

means for detachably connecting said inspection module to the lower end of said cable head subassembly module;

an outer flow tube mechanically connected to said inspection module and surrounding both of said modules to define an annular space therebetween, said tube having its upper end fluid coupled to said coiled tubing for conducting the flow of said optically clear and/or acoustically homogeneous fluid down along said annular space and out the lower end of said tool to create a region conducive to inspection by said tool;

wherein said cable head subassembly comprises;

a crossover adapter for direct mechanical and fluid connection to the lower end of said coiled tubing, said adapter being closed at the bottom and including at least one port formed therein to allow the fluid flowing down said coiled tubing to pass to the outside of said adapter and into the annular region contained within said outer flow tube.

12. A downhole inspection tool as set forth in claim 11 wherein said cable head subassembly comprises:

means for fluid sealing the outside surface of said electrical/fiberoptic cable to said crossover adapter to close the bottom thereof and force the fluid flowing flown said coiled tubing into said adapter to pass out into the annular region through said at least one port.

13. A downhole inspection tool for attachment to the lower end of a length of coiled tubing having an electrical/fiberoptic cable threaded therethrough and carrying a flow of optically clear and/or acoustically homogeneous fluid from a supply of said fluid at the surface, said tool comprising:

a cable head subassembly module attached to the lower end of said coiled tubing and including means for terminating the electrical and optical conductors within said cable;

an inspection module for producing an electrical signal indicative of downhole conditions;

means for detachably connecting said inspection module to the lower end of said cable head module;

an outer flow tube mechanically connected to said inspection module and surrounding both of said modules to define an annular space therebetween, said tube having its upper end fluid coupled to said coiled tubing for conducting the flow of said optically clear and/or acoustically homogeneous fluid down along said annular space and out the lower end of said tool to create a region conducive to inspection by said tool;

wherein said cable head subassembly comprises;

means for mechanically clamping said electrical/fiberoptic cable within said cable head subassembly to prevent disturbance of the termination of its conductors upon application of an upward force upon said coiled tubing to disconnect said subassembly from said inspection module and remove it from within said borehole in the event said outer flow tube becomes lodged downhole.

14. A downhole inspection tool as set forth in claim 13 wherein said outer flow tube includes a fishing neck located near the upper end thereof to enable removal, following removal of said cable head assembly, of said flow tube and inspection module from within said borehole.

15. A downhole inspection tool for attachment to the lower end of a length of coiled tubing having an electrical/fiberoptic cable threaded therethrough and carrying a flow of optically clear and/or acoustically homogeneous fluid from a supply of said fluid at the surface, said tool comprising:

a cable head subassembly module attached to the lower end of said coiled tubing and including means for terminating the electrical and optical conductors within said cable;

an inspection module for producing an electrical signal indicative of downhole conditions;

means for detachably connecting said inspection module to the lower end of said cable head subassembly module;

an outer flow tube mechanically connected to said inspection module and surrounding both of said modules to define an annular space therebetween, said tube having its upper end fluid coupled to said coiled tubing for conducting the flow of said optically clear and/or acoustically homogeneous fluid down along said annular space and out the lower end of said tool to create a region conducive to inspection by said tool;

wherein said electrical/fiberoptic cable includes an inner core of at least one optical fiber surrounded by an stainless steel tube covered with and insulative jacket over which is formed a braided conductive layer also surrounded by an insulative layer over which a stranded conductor is wound for strength, said cable head subassembly further comprising;

means for sealing the outside stranded surface of said cable against the fluid flowing down said coiled tubing and forcing said fluid into said outer flow tube;

means for mechanically clamping the exposed stranded conductor of said electrical/fiberoptic cable to secure the cable within said cable head subassembly and prevent disturbance of the terminations of the conductors therein upon the application of an upward force upon said coiled tubing to disconnect said subassembly from said inspection sensor module and remove it from within said borehole in the event said outer flow tube becomes lodged downhole, said stranded conductor being cut away below said mechanical clamping means to expose said insulative layer;

an enclosed chamber for containing the electrical and optical terminations of the remaining conductors within said cable; and

means for fluid and pressure sealing said insulative layer of said cable against fluid intrusion into said enclosed chamber.

16. A downhole inspection tool as set forth in claim 15 wherein said cable head subassembly also comprises:

means within said enclosed chamber for making electrical connection with the braided conductive layer and the stranded conductor of said cable to supply electrical power from a source at the surface to downhole equipment;

means within said enclosed chamber for making optical termination with said at least one optical fiber comprising the inner core of said cable; and

a light emitting diode housing mounted for longitudinal movement within said enclosed chamber to position a diode in direct abutting relationship with the butt end of the terminated at least one optical fiber irrespective of the length of said cable within said chamber.

17. A downhole inspection tool as set forth in claim 16 wherein said cable head subassembly further comprises:

a light emitting diode mounted within said housing and connected to electrical signal carrying conductors for converting the signals on said conductors into light signals and coupling said light signals into said at least one optical fiber for transmission up said cable to the surface;

a pressure and fluid sealed chamber bulkhead closing the lower end of said enclosed chamber and including a through connector for making electrical connection with each of said electrical signal and electrical power carrying conductors; and

a connector for detachably coupling to the terminals of said chamber bulkhead through connector and having electrical leads connected to each of said signal and power conductors outside of said enclosed chamber.

18. A downhole inspection tool as set forth in claim 17, in which said enclosed chamber comprises:

a pair of semi-cylindrical shells joined at opposite edges to form said chamber, said shells being separable from one another to allow access to the electrical and optical connections therein; and

a cylindrical housing positioned around said assembled shells and sealed thereto near opposite ends thereof to form a fluid and pressure tight enclosed for said connections.

19. A downhole inspection tool as set forth in claim 18 in which said inspection module further comprises:

a fishing neck housing having a fishing neck extending up into the open lower end of said cylindrical housing;

a quick disconnect connector assembly mounted to the lower end of said fishing neck housing, said assembly including a housing through connector bulkhead having electrical terminals on both sides thereof;

means for detachably connecting the electrical leads of each of said signal and power conductors from the connector coupled to said chamber bulkhead through connector to one of the electrical terminals on the top of said housing through connector; and

shear wire means for securing said cylindrical housing to said fishing neck housing and adapted to shear off upon a preselected upward tension upon said coiled tubing and enable withdrawal of said cable head subassembly module from within said borehole to leave said fishing neck exposed for subsequent retrieval of said inspection module.

20. A downhole inspection tool as set forth in claim 19 in which said outer flow tube also includes an inner fishing neck formed near the upper end thereof for retrieval from the surface.

21. A downhole inspection tool as set forth in claim 19 which also comprises:

a camera adapter bulkhead having a first upper connector for detachably connecting to each one of the electrical terminals on the bottom of said housing through connector from an electronics package contained within said inspection module; and

means for mechanically attaching said camera adapter bulkhead to said outer flow tube.

22. A downhole inspection tool as set forth in claim 18 in which said cylindrical housing includes an open portion extending beyond the lower end of said assembled shells and said tool further comprises:

an injector feed through boot protector having a diameter approximately the same as that of said cylindrical housing for detachable connection to the lower end thereof to receive the electrical leads connected to each of said signal and power conductors outside of said enclosed chamber and to guide insertion of said cable head subassembly module and said coiled tubing through a coiled tubing injector, said boot protector being replaceable by said inspection module following said insertion.

23. A downhole inspection tool as set forth in claim 15, in which said enclosed chamber comprises:

a pair of semi-cylindrical shells joined at opposite edges to form said chamber, said shells being separable from one another to allow access to the electrical and optical connections therein; and

a cylindrical housing positioned around said assembled shells and sealed thereto near opposite ends thereof to form a fluid and pressure tight enclosure for said connections.

24. A downhole inspection system comprising:

a length of coiled tubing for carrying a flow of optically clear and/or acoustically homogeneous fluid from a supply of said fluid at the surface;

an electrical/fiberoptic cable threaded through said coiled tubing for carrying electrical power and signals between the surface and a downhole location;

a cable head subassembly module attached to the lower end of said coiled tubing and including means for mechanically clamping said cable to secure said cable within said subassembly and a fluid and pressure sealed chamber for containing terminations of downhole ends of the electrical and optical conductors within said cable and means for converting an electrical signal to an optical signal and transmitting said signal ion the optical conductors of said cable;

an inspection module for producing an electrical signal indicative of downhole conditions;

means for detachably connecting said inspection module to the lower end of said cable head assembly module for both mechanical support thereof and for coupling the electrical signal produced by said inspection module to said signal converting means within said sealed chamber;

an outer flow tube mechanically connected to said inspection module and surrounding both of said modules to define an annular space therebetween, said tube having its upper end fluid coupled to said coiled tubing for conducting the flow of said optically clear and/or acoustically homogeneous fluid down along said annular space and out the lower end of said tool to create a region conducive to inspection by said inspection module;

wherein said cable head subassembly module also includes;

a crossover adapter for direct mechanical and fluid connection to the lower end of said coiled tubing, said adapter being closed at the bottom and including a plurality of ports formed therein to allow the fluid flowing down said coiled tubing to pass to the outside of said adapter and into the annular region contained within said outer flow tube.

25. A downhole inspection system comprising:

a length of coiled tubing for carrying a flow of optically clear and/or acoustically homogenous fluid from a supply of said fluid at the surface;

an electrical/fiberoptic cable threaded through said coiled tubing for carrying electrical power and signals between the surface and a downhole location;

a cable head subassembly module attached to the lower end of said coiled tubing and including means for mechanically clamping said cable to secure said cable within said subassembly and a fluid and pressure sealed chamber for containing terminations of downhole ends of the electrical and optical conductors within said cable and means for converting an electrical signal to an optical signal and transmitting said signal on the optical conductors of said cable;

an inspection module for producing an electrical signal indicative of downhole conditions;

means for detachably connecting said inspection module to the lower end of said cable head assembly module for both mechanical support thereof and for coupling the electrical signal produced by said inspection module to said signal converting means within said sealed chamber;

an outer flow tube mechanically connected to said inspection module and surrounding both of said modules to define an annular space therebetween, said tube having its upper end fluid coupled to said coiled tubing for conducting the flow of said optically clear and/or acoustically homogenous fluid down along said annular space and out the lower end of said tool to create a region conducive to inspection by said inspection module; and

wherein said cable head subassembly module also includes;

a crossover adapter for direct mechanical and fluid connection to the lower end of said coiled tubing, said adapter being closed at the bottom and including a plurality of ports formed therein to allow the fluid flowing down said coiled tubing to pass to the outside of said adapter and into the annular region contained within said outer flow tube; and

means for fluid sealing the outside surface of said electrical/fiber optic cable to said crossover adapter to close the bottom thereof and force the fluid flowing down said coiled tubing into said adapter to pass out into the annular region through said ports.

26. A downhole inspection system comprising:

a length of coiled tubing for carrying a flow of optically clear and/or acoustically homogeneous fluid from a supply of said fluid at the surface;

an electrical/fiberoptic cable threaded through said coiled tubing for carrying electrical power and signals between the surface and a downhole location;

a cable head subassembly module attacked to the lower end of said coiled tubing and including means for mechanically clamping said cable to secure said cable within said subassembly and a fluid and pressure sealed chamber for containing terminations of downhole ends of the electrical and optical conductors within said cable and means for converting an electrical signal to an optical signal and transmitting said signal on the optical conductors of said cable;

an inspection module for producing an electrical signal indicative of downhole conditions;

means for detachably connecting said inspection module to the lower end of said cable head assembly module for both mechanical support thereof and for coupling the electrical signal produced by said inspection module to said signal converting means within said sealed chamber;

an outer flow tube mechanically connected to said inspection module and surrounding both of said modules to define an annular space therebetween, said tube having its upper end fluid coupled to said coiled tubing for conducting the flow of said optically clear and/or acoustically homogeneous fluid down along said annular space and out the lower end of said tool to create a region conducive to inspection by said inspection module;

wherein said electrical/fiber optic cable includes an inner core of at least one optical fiber within a steel tube surrounded by an insulative jacket over which is formed a braided conductive layer also surrounded by an insulative layer over which a stranded conductor is wound for strength, said cable head subassembly module also including;

means for fluid sealing the outside surface of said cable against the fluid flowing down said coiled tubing; and

means for mechanically clamping the exposed stranded conductor of said electrical/fiber optic cable to secure the cable within said cable head subassembly and prevent disturbance of the terminations of the conductors thereof upon application of an upward force upon said coiled tubing to disconnect said subassembly from said inspection sensor module and remove it from within said borehole in the event said outer flow tube becomes lodged downhole, said stranded conductor being cut away below said mechanical clamping means to expose said insulative layer.

27. A downhole inspection system comprising:

a length of coiled tubing for carrying a flow of optically clear and/or acoustically homogeneous fluid from a supply of said fluid at the surface;

an electrical/fiberoptic cable threaded through said coiled tubing for carrying electrical power and signals between the surface and a downhole location;

a cable head subassembly module attached to the lower end of said coiled tubing and including means for mechanically clamping said cable to secure said cable within said subassembly and a fluid and pressure sealed chamber for containing terminations of downhole ends of the electrical and optical conductors within said cable and means for converting an electrical signal to an optical signal and transmitting said signal on the optical conductors of said cable;

an inspection module for producing an electrical signal indicative of downhole conditions;

means for detachably connecting said inspection module to the lower end of said cable head assembly module for both mechanical support thereof and for coupling the electrical signal produced by said inspection module to said signal converting means within said sealed chamber;

an outer flow tube mechanically connected to said inspection module and surrounding both of said modules to define an annular space therebetween, said tube having its upper end fluid coupled to said coiled tubing for conducting the flow of said optically clear and/or acoustically homogeneous fluid down along said annular space and out the lower end of said tool to create a region conducive to inspection by said inspection module;

wherein said sealed chamber of said cable head subassembly comprises;

a pair of semi-cylindrical shells joined at opposite edges to form said chamber, said shells being separable from one another to allow access to the electrical and optical connections therein; and

a cylindrical housing positioned around said assembled shells and sealed thereto near opposite ends thereof to form a fluid and pressure tight enclosure for said connections.