Connector assembly for coiled tubing

Abstract

 A connector assembly (26) for connecting coiled tubing (20) to downhole equipment in an earth well, includes a tubular housing (28) for connecting the coiled tubing (20) to the equipment, the housing including a bore for receiving fluid from the coiled tubing. At least one passage (28a,28c,28b,28d) extends through the housing (28) and communicates the bore with said well, and a valve (38a,38b) is provided for controlling the flow of fluid through the passage between the housing (28) and the well. The assembly can accommodate an elongated member, such as an electrical cable, or the like.

Description

[0001] The present invention relates to a connector assembly for connecting coiled tubing to a tool for operating in an oil and gas earth well and, more particularly, to such an assembly for selectively controlling the flow of fluid from the coil tubing into the well.

[0002] In the operation of subterranean oil and gas earth wells, it is often necessary to perform several downhole operations in the well. To this end, many different types of downhole tools have evolved which often are inserted in the well by wireline to a predetermined depth where they perform their functions.

[0003] Coiled tubing is now often being used in these types of downhole applications in place of the wireline since the coiled tubing has several advantages. For example, coiled tubing can traverse highly deviated or horizontal wells and fluids or gases can be discharged through the coiled tubing and into the well for various purposes such as actuating hydraulic equipment, cleaning and/or replacing any fluids displaced as a result of the insertion of the coiled tubing and the associated tool, etc. Also, radioactive fluids, foam, paraffin, nitrogen, mud, corrosion inhibitors, spotting acid, cement, and the like, can be introduced into the well for performing various functions. Further, in certain circumstances, fluid, such as water, can be circulated through the coiled tubing to maintain a pressure balance across the wall of the coiled tubing when well fluids are acting on the outer surface of the wall.

[0004] In order to provide for discharge of the fluid or gas into the wellbore, a tubular adapter- or housing is usually connected between the coiled tubing and the downhole tool. One or more passages are provided through the wall of the adapter for receiving the fluid or gas from the coiled tubing and discharging it into the wellbore. For example, in our U.S. patent specification no. 5,040,598, a pulling tool is disclosed which is connected to reeled, or coiled, tubing by an assembly including an inner mandrel and a tubular core. A plurality of angularly spaced passages extend through the core for discharging fluid from the bore of the core externally of the core. However, in situations when the wellbore often contains fluid or gas under pressure, the fluids or gas could escape through the passage in the adapter and backflow through the coiled tubing to the ground surface. This, of course, could present a safety hazard, especially in the event of failure of any of the above-ground equipment.

[0005] The above problem is compounded when the downhole tool requires electrical power which necessitates the provision of electrical cable extending from a power source above ground, through the coiled tubing and the adapter, and to the tool. Since this creates space limitations in the bore of the adapter, it is difficult, if not impossible, to install valving to control the fluid flow through the passage in the adapter.

[0006] We have now devised a connector assembly for connecting coiled tubing to a downhole tool, whereby the prior art disadvantages are reduced or overcome.

[0007] According to the present invention, there is provided a connector assembly for use with coiled tubing in an earth well, said assembly comprising a tubular housing for connecting said coiled tubing relative to equipment for operating in said well so that operating fluid from above ground can pass through said coiled tubing and into the bore of said housing, passage means extending through said housing and communicating said bore with said well, and valve means associated with said passage means for controlling the flow of fluid between said bore and said well.

[0008] Preferably, said valve means is arranged normally to prevent the flow of well fluid from said well, through said passage means and into said bore, and to respond to a predetermined pressure of said operating fluid in said bore for permitting the flow of said operating fluid from said bore, through said passage means and into said well.

[0009] The invention also includes the connector assembly when connected to coiled tubing and a downhole tool to provide the connection therebetween.

[0010] In order that the invention may be more fully understood, an embodiment thereof will now be described, by way of example only, with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic view, partially in elevation and section, and partially broken away, of an earth well showing the illustrative embodiment of the present invention inserted therein; and

FIG. 2 is an enlarged, longitudinal, cross-sectional view of the assembly embodiment of the present invention.

[0011] Referring to FIG. 1 of the drawings, the reference numeral 10 refers to a casing passing through a vertical earth well 12. A string of well tubing 14 is located in the casing 10 and extends in a coaxial relationship to the casing. Two axially spaced packers 16 and 18 extend in the annular space between the outer surface of the tubing 14 and the inner surface of the casing 10 to isolate and seal the space therebetween, in a conventional manner. It is understood that other packers can be provided in a spaced relation to the packers 16 and 18, as needed.

[0012] A section of coiled tubing 20 is stored on a reel 22 above ground and is injected into the casing 10 and the well tubing 14 by an injector 24. It is understood that a manifold (not shown) is provided which includes the necessary pumps, valves, and fluid reservoirs to discharge a fluid into and through the coiled tubing 20. It is also understood that a wellhead valve (not shown) is used to control vertical access to, and fluid communication with, the upper portion of the well tubing, and blowout preventers, or other sealing equipment (not shown), can be installed to block fluid flow during emergency conditions. Since these components are conventional they will not be described in any further detail.

[0013] An adapter assembly 26 is connected to the distal end of the coiled tubing 20 and is for the purpose of connecting the coiled tubing to a downhole tool, or other similar equipment (not shown). As better shown in FIG. 2, the assembly 26 includes an elongated tubular housing 28, the upper end portion of which defines an irregular surface. The distal end portion of the coiled tubing 20 is crimped over the above-mentioned upper end portion of the housing 28 to secure the coiled tubing to the housing in a conventional manner. A pair of axially spaced annular seal rings 30a and 30b extend in corresponding grooves formed in the outer surface of the housing 28 and in sealing engagement with the corresponding inner surface of the coiled tubing 20.

[0014] An electrical cable 32 extends from above ground and through the length of the coiled tubing 20 for connecting to a downhole tool or other type equipment (not shown) extending below, and connected relative to the housing 28. The outer surface of the cable 32 is spaced from the inner surface of the housing 28 to define an annular chamber for receiving operating fluid, as will be described.

[0015] A portion of the housing 28 is milled out to form two diametrically opposed, radial passages 28a and 28b extending inwardly from the outer surface of the housing 28, and two diametrically opposed angled passages 28c and 28d extending from the bore of the housing to the passages 28a and 28b.

[0016] Two additional portions of the outer surface of the housing 28 are milled out in the vicinity of the passages 28a and 28c and the passages 28b and 28d, respectively, to form two diametrically opposed, enlarged grooves, 28e and 28f, respectively. The groove 28e communicates with the passages 28a and 28c and the groove 28f communicates with the passages 28b and 28d. Two ball valves 34a and 34b are located at the lower ends of the passages 28a and 28b, respectively, and are sized to seal off the passages under conditions that will be described. Two spring retainers 36a and 36b engage the ball valves 34a and 34b, respectively, and two helical compression springs 38a and 38b extend between the retainers 36a and 36b and two spring caps 40a and 40b, respectively. The spring caps 40a and 40b are wedged in an area between the corresponding outer surface portions of the housing 28 and a jam-nut sleeve 42 which is in threaded engagement with a corresponding threaded outer surface portion of the housing 28. Thus, upward advancement of the sleeve 42 relative to the housing 28 wedges the spring caps 40a and 40b in the position shown.

[0017] The springs 38a and 38b normally bias the ball valves 34a and 34b into a seating position against the corresponding surfaces of the housing 28 where they block the passages 28a and 28b, respectively. However, the springs 38a and 38b are each calibrated to yield to a predetermined force against the ball valves 34a and 34b caused by fluid pressure in the passages 28a and 28b exceeding a predetermined amount to permit flow through the latter passages, under conditions that will be described. FIG. 2 depicts the ball valve 34a in its open position and the ball valve 34b in its closed position for the purpose of illustration only, it being understood that under normal conditions, both valves would operate in the same manner, as will be described.

[0018] The bore of the tubular housing 28 is enlarged at its lower end portion and tapered at the upper end of the enlarged portion to receive a packoff member 44 of a resilient material such as rubber, which sealingly engages the corresponding outer surface of the cable 32 and the inner surface of the housing 28. The upper end portion of the packoff member 44 is tapered to correspond to the taper of the corresponding tapered surface of the bore of the housing 28, and the lower end portion of the member 44 is similarly tapered for engagement by a packoff nut 46, the upper end portion of which has a complemental taper.

[0019] The packoff nut 46 has an outer threaded surface in threaded engagement with a corresponding inner threaded surface of the housing 28 so that upward advancement of the packoff nut 46 against the packoff member 44 forces the latter member into sealing engagement with the corresponding outer surface of the cable 32 and the inner surface of the housing 28. The lower end portion of the housing 28 extends below the lower end of the packoff nut 46 and has an internally threaded portion for receiving a downhole tool (not shown) and its associated apparatus such as a cable clamp, an adapter, etc.

[0020] In operation, the connector assembly 26 is connected to the coiled tubing 20 by crimping the lower end portion of the coiled tubing over the upper end portion of the housing 28 as described above, and a downhole tool including a string of associated equipment is connected to the lower end portion of the housing 28. For example, the downhole tool could be an electrical operated device such as a pump, a seismic device, a camera, etc., in which case a cable clamp, or other similar device, would be connected to the lower end of the housing 28. The other end of the cable clamp would be connected to other associated devices such as an electrical connector, a fishing neck sub, etc. and a socket assembly would be provided at the end of the string for receiving the downhole tool.

[0021] The coiled tubing 20, with the connector assembly 26 and the above-mentioned downhole tool and string of associated equipment, is lowered to a predetermined position in the tubing 14. During this operation the springs 38a and 38b bias the ball valves 34a and 34b, respectively, against the corresponding end portions of the passages 28c and 28d, respectively, to prevent any well fluids in the tubing 14 from backflowing through the passages 28a and 28b, the passages 28c and 28d and through the annular space between the coiled tubing 20 and the cable 32.

[0022] In the event the well needs to be cleaned out or conditioned as discussed above, appropriate fluid can be introduced from above ground, into the coiled tubing 20 where it would pass through the annular chamber between the cable 32 and the coiled tubing to the connector assembly 26. The fluid would be at sufficient pressure to urge the ball valves 34a and 34b against the resistance of the springs 38a and 38b to open the passages 28c and 28d and communicate them with the passages 28a and 28b, respectively. Thus, the fluid would flow from the passages 28a and 28b into the annular space between the outer surface of the connector assembly 26 and the inner wall of the tubing 14 for one or more of the purposes discussed above.

[0023] After the above-mentioned operation is concluded, the flow of the fluid from above ground into the coiled tubing and the connector assembly 26 is terminated and the ball valves 34a and 34b are urged into a flow-blocking position relative to the passages 28c and 28d, respectively. This eliminates the danger of well fluids escaping through the passages 28a-28d and backflowing through the coiled tubing 20 during inaction or removal of the tool from the well, as described above.

[0024] It is thus seen that, according to the present invention, coiled tubing can be connected relative to a downhole tool or other similar equipment in a manner to permit fluid to be selectively passed through the coiled tubing and the connector housing and into the well for performing various functions, while preventing the backflow of well fluid through the system at all times. Moreover, this is achieved while accommodating an electrical cable, or any other similar device, in the bores of the coiled tubing and the connector housing.

[0025] It is understood that several variations may be made in the foregoing without departing from the scope of the invention. For example, the assembly of the present invention is not limited to use with an electrical cable, but can accommodate any other elongated device in the bore of the assembly, such as a data transmission line, a power transmission line, a fluid transmission line, fiber optic cable, etc. Also, although two valve assemblies and passages are shown and described above by example, it is understood that any number of such assemblies and passages can be provided in an angularly-spaced relationship around the housing within the scope of the invention. Further, the assembly of the present invention is not limited to operation within well tubing, but can function in environments in which there is no well tubing or casing.

Claims

1. A connector assembly (26) for use with coiled tubing (20) in an earth well, said assembly comprising a tubular housing (28) for connecting said coiled tubing relative to equipment for operating in said well so that operating fluid from above ground can pass through said coiled tubing and into the bore of said housing, passage means (28a,28c;28b,28d) extending through said housing (28) and communicating said bore with said well, and valve means (34a,34b) associated with said passage means (28a,28c; 28b,28d) for controlling the flow of fluid between said bore and said well.

2. An assembly according to claim 1 wherein said valve means (34a,34b) is arranged normally to prevent the flow of well fluid from said well, through said passage means (28a,28c,28b,28d) and into said bore, and to respond to a predetermined pressure of said operating fluid in said bore for permitting the flow of said operating fluid from said bore, through said passage means (28a,28c,28b,28d) and into said well.

3. An assembly according to claim 1 or 2, wherein said passage means (28a,28c,28b,28d) extends from the inner surface of said bore to the outer surface of said housing and wherein said valve means comprise at least one passage extending through the wall of said housing (28).

4. An assembly according to claim 1, 2 or 3, wherein said passage means (28a,28c,28b,28d) comprise at least one passage extending through the wall of said housing (28).

5. An assembly according to claim 1, 2, 3 or 4, wherein said valve means (34a,34b) comprises a ball valve and spring means (36a,36b) for urging said ball valve to said flow-preventing position in said passage (28a,28c, 28b,28d).

6. An assembly according to any of claims 1 to 5, wherein there are two diametrically opposed passages (28a,28c;28b,28d) formed through said housing wall and two ball valves (34a;34b) respectively associated with said passages.

7. An assembly according to any of claims 1 to 6, wherein said housing (28) is connected to said coiled tubing (20), and wherein an elongated member (32) extends through said coiled tubing (20) and said bore of said housing (28) for connection to said equipment.

8. An assembly according to claim 7, wherein said elongated member (32) is a data transmission line, a power transmission line, or a fluid transmission line.

9. An assembly according to claim 7 or 8, wherein the housing is connected to equipment for working in the well.

10. The use of a connector assembly (26) as claimed in any of claims 1 to 6, for connecting coiled tubing (20) to downhole equipment and for controlling flow of fluid from the tubing (20) into the well.

Drawing