Disconnect check valve mechanism for coiled tubing

[0002] 1. Field of the Invention

[0003] The present invention relates generally to a disconnect check valve mechanism that is applicable for releasable connection with a wide variety of payloads such as direct circulating flow valves, reverse circulating flow valves, formation fracturing tools and the like. More specifically, the present invention concerns a disconnect check valve mechanism that is connected to a payload, run into a well, and operated in a reverse circulating flow condition until its disconnect is actuated, leaving the payload within the well and permitting retrieval of the disconnect check valve mechanism with its check valve or valves enabled, thus permitting only direct circulating flow and preventing the inflow of wellbore fluids into the tubing string.

[0004] 2. Description of Related Art

[0005] It is a safety standard in coiled tubing operations, to have a check valve assembly with a minimum of two pressure barriers in the tool string. In many coiled tubing operations, such as fracturing and well cleanout operations, it is desirable to reverse circulate through the coiled tubing. Reverse circulating (flowing upwardly within the passage of the coiled tubing instead of downwardly) is not possible when a conventional direct circulating dual check valve mechanism is employed.

[0006] It is a principal feature of the present invention to provide a novel tubing supported disconnect check valve mechanism or tool that functions as a passive selectively operated disconnect apparatus to which a variety of well servicing tools or payloads may be connected for use in a variety of well servicing applications.

[0007] It is also a feature of the present invention to provide a novel tubing supported disconnect check valve mechanism that can be selectively disconnected from the payload to which it is connected, and retrieved from the well with its check valve or valves in the retrieved portion thereof enabled, thus permitting direct circulating flow only while preventing the inflow of wellbore fluids into the tubing.

[0008] It is another feature of the present invention to provide a novel tubing supported disconnect check valve mechanism that accommodates industry safety standards when the tubing being utilized within the well is coiled tubing, so that downhole check valve barriers are provided during retrieval to prevent the inflow of wellbore fluids into the tubing.

[0009] Briefly, the various objects and features of the present invention are realized by providing a tubing supported disconnect check valve mechanism that is run into a wellbore connected with a payload in the form of a well servicing tool (which may be as simple as a ported bullnose), and with its check valve disabled by a mandrel within the disconnect check valve mechanism which is normally maintained at a check valve disabling position and is selectively released from its retained position and moved to a check valve enabling position. The disconnect check valve mechanism is normally passive within the tool until such time as disconnect and retrieval becomes desirable or necessary. For retrieval of the disconnect check valve mechanism, the internal mandrel is actuated to its valve enabling position, thus enabling the check valve or valves to prevent reverse circulating flow and the inflow of wellbore fluids while permitting direct circulating flow. The internal mandrel can be actuated to its valve enabling position by a drop ball and tubing pressure, by tension, by pressure differential, or by any other suitable means, and is retrieved along with the disconnect check valve mechanism after separation of the disconnect check valve mechanism from the payload tool. The housing of the payload or well servicing tool defines an internal pulling profile, thus permitting its retrieval by a fishing tool, spear, overshot, or any other type of retrieving tool.

[0010] After a well servicing operation has been completed, assuming the payload well servicing tool is to be retrieved from the well, as is typically the case, a tension force is applied to the housing of the disconnect check valve mechanism via the tubing string, thus moving the disconnect check valve mechanism and its connected payload upwardly within the well to the surface. The disconnect check valve mechanism will have remained passive during tool running, servicing operations, and during retrieval. In the event the payload well servicing tool should become stuck within the well, or if another condition should occur that makes it desirable to disconnect the disconnect check valve mechanism from the well servicing tool, the disconnect mechanism can be actuated to disconnect from the payload and to enable the check valve or valves for direct circulating flow only and prevention of the inflow of wellbore fluids. When the disconnect check valve mechanism is designed for drop ball and tubing pressure actuation, a closure ball is dropped or pumped through the tubing string to the disconnect check valve mechanism and blocks the flow passage of the internal tubular member or mandrel and, with the mandrel, defines a pressure responsive surface area or piston area. Disconnect actuation pressure is applied via the tubing string to act on the piston area and develop sufficient force to shear retainer pins or otherwise release the inner tubular member or mandrel from its check valve disabling position and shift the mandrel to its check valve enabling position. The inner tubular member or mandrel will then remain at this check valve enabling position within the tubular housing, thus causing the check valve mechanism to remain in its direct circulating flow mode. The mandrel moves down when the closure ball is dropped and the tubing pressured-up, but then comes out of the well with the check valves. This leaves the bore of the payload well servicing tool open and free to receive internal fishing tools after disconnecting.

[0011] So that the manner in which the above recited features, advantages, and objects of the present invention are attained can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the preferred embodiment thereof which is illustrated in the appended drawings, which drawings are incorporated as a part hereof.

[0012] It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0013] In the Drawings:

[0014] FIG. 1 is a longitudinal sectional illustration showing a well completed to a production formation and showing coiled tubing handling apparatus at the surface with coiled tubing being connected to a disconnect check valve mechanism having a payload connected thereto;

[0015] FIG. 2A is a longitudinal sectional view of an upper section of a disconnect check valve mechanism embodying the principles of the present-invention shown in coupled relation with a payload;

[0016] FIG. 2B is a longitudinal sectional view of a lower section of the disconnect check valve mechanism of FIGS. 1 and 2A showing the collet connector of the disconnect mechanism in its connected condition;

[0017] FIG. 3A is a longitudinal sectional view of the upper section of the disconnect check valve mechanism of FIGS. 1 and 2A coupled with a payload and showing a drop ball seated at the upper end of the valve disabling sleeve of the movable tubular internal mandrel with the sleeve being at its lowermost or valve enabling position within the tubular housing;

[0018] FIG. 3B is a longitudinal sectional view of the lower section of the disconnect check valve mechanism of FIGS. 1, 2A, and 3A showing the valve disabling sleeve in the direct circulating flow position with the disconnect mechanism connected to the payload;

[0019] FIG. 4A is a longitudinal sectional view of the upper section of the disconnect check valve mechanism of FIGS. 1, 2A, and 3A showing the check valve mechanism in its direct circulating flow mode as in FIG. 3A; and

[0020] FIG. 4B is a longitudinal sectional view of the lower section of the disconnect check valve mechanism of FIGS. 1, 2A, 3A, and 4A showing the disconnect check valve mechanism having been released by internal mandrel movement and tension force for retrieval from the well, with the payload tool remaining in the well.

[0021] Referring now to the drawings and first to FIG. 1, a trailer or truck mounted mobile coiled tubing unit is shown generally at 10 and incorporates a tubing storage reel 12 from which coiled tubing 14 is run by an injector 15 through a blowout preventer 16 and a wellhead 17 into a well 18. The coiled tubing from the reel 12 passes along a guide 19 as it is moved into the well 18 by the injector 15. A length of production tubing 21 is supported by a hanger within the wellhead 17, with its lower end being sealed to the well casing 20 by a packer 23. The casing 20 is perforated at 22 to permit communication of the well with a production formation 24, from which petroleum products such as crude oil and natural gas are produced. The coiled tubing string 14 extends through the production tubing 21 to a desired depth within the well, typically a location above the casing perforations 22 as shown. A connector 26 is provided at the lower end of the coiled tubing, for support of a disconnect check valve mechanism, shown generally at 28, which embodies the principles of the present invention and which provides for releasable connection with a payload or well servicing tool 30 of any suitable character.

[0022] For injection of fluid through the coiled tubing and disconnect check valve mechanism into the well, a conduit 31 is connected to the centermost coil of the coiled tubing on the storage reel 12 and permits fluid from a supply tank (not shown) to be pumped through the coiled tubing. Although a casing is shown within the well, it is not intended to limit the present invention for use in wells having casings, it being intended that the present invention be applicable to open bore applications as well.

[0023] As mentioned above, it is desirable to provide a disconnect check valve mechanism that is designed for compliance with industry standards for coiled tubing applications in wells and to permit the connection of a well servicing tool, or payload thereto. The disconnect feature permits the disconnect check valve mechanism to be separated from the payload in the downhole environment and retrieved from the well with its check valve or valves enabled for flow responsive closure, thus permitting the payload to remain downhole. During retrieval of the disconnect check valve mechanism from the well, after disconnection has occurred, the check valve or valves will function to prevent reverse circulating flow and permit direct circulating flow, while preventing the inflow of wellbore fluids. It is to be borne in mind that the disconnect check valve mechanism has application in combination with a number of different types of payload tools for conducting well servicing operations. The disconnect check valve mechanism is particularly useful for releasable connection with a tool that can be run into a well in a reverse circulating flow mode to promote well clean-out using reverse circulating flow, with fluid being injected into the annulus of the well and caused to flow at relatively high velocity through the check valve mechanism and the tubing string to the surface, transporting sand and other constituents to the surface along with the fluid.

[0024] Referring now to FIGS. 2A and 2B, a disconnect check valve mechanism representing the preferred embodiment of the present invention, shown at 28 in FIG. 1, effectively accomplishes the aforementioned features. The disconnect check valve mechanism 28, comprises a tubular housing shown generally at 32 which is defined by a valve housing section 34 and an upper housing section 36 having a disconnect mechanism for connection of the disconnect check valve mechanism with, and for separation from, a payload, which is typically a well servicing tool. The upper end of the valve housing section 34 of the tubular housing 32 establishes a threaded connection 40 with a tubing connector 42, such as a tubing connector at the lower end of a tubing string 43 and is sealed to the tubing connector 42 by an O-ring seal 44.

[0025] Within the valve housing section 34 is maintained a check valve assembly shown generally at 46 which may be in the form of a dual check valve assembly having upper and lower valve bodies 48 and 50 providing operative support for upper and lower pivotal flapper type check valves 52 and 54. Though dual flapper type check valves are shown, a single check valve may be employed as well. It should also be borne in mind that the check valves may take the form of poppet type check valves, ball type check valves, or any other suitable type of check valves without departing from the spirit and scope of the present invention. The valve bodies 48 and 50 of the check valve assembly are sealed with respect to the inner surface of the valve housing section 34 by O-ring seals 56 and 58. The check valves 52 and 54 are each capable of opening responsive to downward, i.e., direct circulating flow of fluid from the tubing string through a central flow passage 60 of the connector 42, such as during injection of treating or fracturing fluid into the well. The check valves 52 and 54, when enabled for direct circulating flow, are moved to the closed positions thereof, such as shown in FIG. 3A, responsive to upward or reverse circulating flow of fluid from the well or from the annulus between the tool and the well casing or wellbore.

[0026] The upper housing section 36 of the tubular housing 32 is connected with the lower end of the valve housing by a threaded connection 62, with an O-ring seal 64 maintaining a sealed condition between the valve housing section 34 and the upper housing section 36. The position of the check valve assembly within the valve housing is maintained by a lower annular shoulder 66 of the connector 42 and by an annular shoulder 68 that is defined by the upper end of the upper housing section 36. The upper housing section 36 further defines a pressure relief port 70, the function of which is described in detail below.

[0027] In FIGS. 2A and 2B an inner tubular member or mandrel 72 is shown which is normally immovably secured within the tubular housing 32, except when a disconnect procedure is desired, and is then released from the tubular housing 32 and moved linearly to close the reverse circulating flow path and to position the check valve mechanism for direct circulating flow only. The inner tubular member or mandrel 72 is sealed with respect to the upper housing section 36 by an O-ring seal 74 or any other suitable annular sealing member. The inner tubular member 72 defines a central flow passage 76 through which fluid flows as it is injected into the well during direct circulating flow or when reverse circulating flow is occurring. A tubular valve disabling sleeve 78 extends upwardly from the inner tubular member 72 and, as shown in FIG. 2A, is positioned within the flow passage of the check valve assembly 46 for disabling the check valves 52 and 54 by maintaining the check valves in their fully open positions and preventing their pressure responsive closure. The valve disabling sleeve 78 defines an annular ball seat 80 at its upper end, which is best shown in FIG. 2A. The disconnect check valve mechanism 28 and its payload tool 30 is typically run into a well with the inner tubular member 72 retained in the valve disabling position shown in FIGS. 2A and 2B, thus enabling both direct and reverse circulating flow. One or more shear pins 82 are threaded through the upper housing section 36 with the inner ends of the shear pins 82 being received within shear pin receptacles 84 that are defined in the outer peripheral surface portion of the inner tubular member 72. The shear pin or pins 82 will be sheared when a downward force of predetermined magnitude is applied to the inner tubular member 72, thereby releasing the inner tubular member from its retained condition and permitting its downward movement within the tubular housing 32 to the check valve enabled position shown in FIGS. 3A and 4A. To accomplish shearing of the shear pins 82 and release of the inner tubular member 72 from the upper housing section 36, a closure member 86, such as a drop ball, or closure element of any other acceptable type, is dropped or pumped through the tubing string 43 and through the flow passage 60 and becomes seated on the annular ball seat 80. The drop ball type closure member 86 closes the flow passage of the inner tubular member 72 and defines a pressure responsive surface area or piston area having a piston dimension or area that is defined by circular contact of the annular seal element 74 with the inner cylindrical surface 88 of the upper housing section 36. Fluid pressure injected through the tubing string 43 into the tubular housing 32 acts on the piston area and establishes a pressure differential which develops a pressure responsive force acting downwardly on the inner tubular member or mandrel 72. When this (pressure times area) downward force exceeds the predetermined force required to shear the shear pins 82, the shear pins 82 will be sheared and the inner tubular member 72 will be released from its retained check valve disabling position. The downward pressure responsive force acting on the inner tubular member 72 will then move the inner tubular member or mandrel 72 downwardly until the annular seal member 74 moves across the pressure relief port 70, allowing the injected pressure to vent to the annulus of the wellbore or casing surrounding the tool. Relief or venting of the injected pressure in this manner dissipates the pressure responsive downward force acting on the inner tubular member 72 and minimizes the potential for slamming of the inner tubular member 72 within the tubular housing 32. Maximum downward travel of the inner tubular member 72 is limited by an upwardly facing annular stop shoulder 90, which is engaged by a downwardly facing annular shoulder 92 of the inner tubular member 72. Pressure responsive downward movement of the inner tubular member 72 in this manner causes the tubular valve disabling sleeve 78 to be withdrawn from the FIG. 2A position within the check valve assembly to a position clear of the check valves 52 and 54 and thus enables the check valves for reverse circulating flow responsive closing movement. This mandrel releasing and shifting activity will typically be done when it is desired to release the disconnect check valve mechanism from the payload. This feature permits the disconnect check valve mechanism to be retrieved in its direct circulating flow mode, thus providing one or more check valve barriers as is currently required by industry standards for coiled tubing applications in wells. As soon as the check valves have been opened by pressure responsive movement of the inner tubular member 72 to its lowermost position within the upper housing section 36, thus positioning the check valve mechanism for its direct circulating flow mode, the direct circulating flow mode can be confirmed at the surface by a reduction in pressure in the tubing string.

[0028] Referring to FIGS. 2B, 3B, and 4B, which are longitudinal sectional views each showing the lower portion of the disconnect check valve mechanism 28 and its releasable connection with the payload well servicing tool 30, it is desirable to provide a releasable coupling feature which permits the disconnect check valve mechanism to be simply and efficiently separated from the payload well servicing tool as desired. The payload housing 38 has an upper end 94 that receives a lower reduced diameter connection extension 96 of the upper housing section 36. An annular seal, such as an O-ring seal 98, maintains sealing of the upper housing section 36 and the payload housing 38. The internal pulling profile 104 of the payload housing 38 has an upper annular internal profile recess 106, a lower annular internal profile recess 108 and an intermediate annular profile recess 110. The lower reduced diameter connection extension 96 is machined or otherwise formed to define a plurality of elongate flexible collet fingers 112, each having lower ends defining locking dogs 114 that are received within the profile recesses of the internal pulling profile 104 when the collet fingers 112 are expanded.

[0029] The circular array of flexible collet fingers 112 collectively define a generally cylindrical connecting and releasing collet, with each of the flexible collet fingers 112 forced radially inwardly to the unlocking or releasing positions shown in FIG. 4B. In this position the locking dogs 114 are retracted from the upper and lower internal profile recesses 106, 108 and may engage the outer cylindrical surface of a tubular extension 124 of the inner tubular member 72. The locking dogs 114 each define tapered upper retention shoulders 116 and tapered lower guide shoulders 118 that react with internal tapered surfaces of the internal profile recesses for transmission of lateral or radial force to the collet fingers 112 if the locking dogs 114 of the collet fingers 112 do not completely retract from the profile recesses 106, 108 when collet unlocking occurs. The tapered upper retention shoulders 116 are of substantially matching configuration with internal tapered shoulders 120, 122 of the upper and lower annular internal profile recesses 106, 108 to thus establish a designed tension force for disconnect release and to permit initial upward movement of the collet relative to the internal pulling profile of the payload housing 38. When the collet has been unlocked from the internal pulling profile 104 and pulling tension is applied to the tubing string 43, the locking dogs 114 of the resilient collet fingers 112 will retract from the profile recesses. Thus, the tension force for disconnect separation is relatively minimal and is well within the tension force limits of coiled tubing. During this upward movement of the disconnect check valve mechanism, the seal of the annular sealing element 98 with the inner surface of the upper end 94 of the payload housing 38 will be broken and the inner tubular member or mandrel 72 will be retrieved from the well along with the disconnect check valve mechanism.

[0030] When the disconnect components are at the position shown in FIG. 2B, the circular collet finger array is locked with respect to the internal pulling profile 104 of the payload housing 38. The inner tubular member 72, is provided with a reduced diameter lower tubular extension 124 which is of sufficient length to bridge the disconnect mechanism with the inner tubular member 72 positioned at the check valve disabling position thereof as shown in FIGS. 2A and 2B. A collet locking cap 126 is secured by a threaded connection 128 to the lower externally threaded end 130 of the lower tubular extension 124. The collet locking cap 126, when positioned as shown in FIG. 2B, engages the inner surfaces of the locking dogs 114 of the flexible collet fingers 112, expands the collet, and secures the locking dogs 114 within the lower internal profile recess 108 and thus prevents inadvertent separation of the disconnect mechanism. When the collet locking cap 126 has been moved downwardly clear of the locking dogs 114, as shown in FIGS. 3B and 4B, the flexible collet fingers 112 can retract the locking dogs 114 from the lower internal profile recess 108. The collet locking cap 126 carries an external annular dynamic sealing element 134, which establishes sealing with an internal cylindrical surface 138 of the payload housing 38 and maintains such sealing during movement of the inner tubular member 72 between its valve disabling and enabling positions. To ensure that the collet locking cap 126 is maintained stationary with respect to the lower tubular extension 124, a set screw 136 or other suitable retainer is threaded through the locking cap and engages within a receptacle of the lower tubular extension. The lower tubular extension 124 of the inner tubular member 72, together with the collet locking cap 126, permits the lower portion of the inner tubular member 72 to maintain sealing with the internal surface 138 at all positions of the inner tubular member 72 within the payload housing 38. This sealing relation is broken only when the disconnect mechanism is separated and the upper housing section 36, with the inner tubular member or mandrel 72, are moved upwardly during retrieval from the well.

[0031] When disconnection of the check valve mechanism is not needed, the entire payload tool 30 and disconnect check valve mechanism 28 may be retrieved from the well as a unit, simply by applying tension force to the tubular housing 32 via the tubing string 43. The disconnect check valve of the present invention can be modified simply and efficiently to function as a tensile force actuated disconnect or a flow responsive or pressure responsive disconnect without departing from the scope of the present invention.

[0032] In view of the foregoing it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus disclosed herein.

[0033] As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its essential characteristics. The present embodiment is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.