Underwater Completion Expanding Tubing Hanger

Abstract

An apparatus for suspending a string of pipe in an oil or gas well at the wellhead, and particularly for hanging one or more tubing strings in the casing head of an offshore underwater well. Included are an assembly for hanging the tubing strings, a tool assembly for running and retrieving the tubing hanger assembly, and a tool assembly for running and retrieving a tubing hanger coupling and for completing the well. The apparatus facilitates running, aligning, and landing all the tubing strings, pressure testing the tubing hanger, and locking the hanger down, all in one trip.

Description

BACKGROUND OF THE INVENTION

The field of art to which this invention pertains includes devices for suspending pipe in wells or shafts bored into the earth, and more particularly to such devices for suspending one or more strings of tubing from the wellhead. In a specific sense, the invention relates to pipe hangers that include a self-expanding support ring that is adapted to expand into a predesignated groove system in an outer tubular member to land and ultimately lock the hanger to this tubular member, to apparatus for running and retrieving such pipe hangers, to apparatus for completing the well through such pipe hangers and, where desired, for running and retrieving one or more pipe strings through the hanger, and also to methods for carrying out the foregoing.

In the practice of drilling off shore underwater wells for the recovery of valuable fluids such as oil and natural gas, it is customary to support the drilling rig on a floating vessel, or on the ocean, etc. floor when in shallow water, and to complete the well ready for production either on a platform at the water surface or, more modernly, on the bottom or floor of the ocean. Generally speaking, as the water depth increases the degree of difficulty in completing the well, including the time required, also increases. As a result, much effort has been devoted to reducing the time factor involved in completing underwater wells, improving the reliability and safety of the equipment used in such completions, and generally attempting to bring the overall cost factor of underwater well completions more within the reasonable range of land-based wells.

An outstanding example of the results of this endeavor is the Underwater Completion (UWC) system designed and manufactured by the Oil Center Tool (OCT) Division of FMC Corporation, Houston, Texas. This system, described in detail in OCT's booklet entitled "Oil Center Tool Underwater Completion System," involves the following general procedure. The conductor pipe is driven, drilled, or jetted into place. In the conductor string is a conductor housing that attaches to a permanent guide base that rests on the ocean floor. After drilling the hole to the desired depth, the surface casing is attached to the bottom of the wellhead body, and is run using the wellhead body running tool. This surface string is guided into the conductor pipe by a universal guide arm unit. After cementing the surface string, the wellhead body running tool is retrieved. The blowout preventers, which are attached to the top of a "Torus" connector, are run down the guide cables and connected to the wellhead body by this connector. The hole is drilled deeper, the intermediate string is run, cemented, packed off and tested, and the hole then is drilled to completion depth and the oil string is run, using the same procedure as used for the intermediate string. With the blowout preventers in place on the wellhead body, the test plug is removed, and the tubing hanger and tubing strings are run, completing the well. The present invention concerns a new type of tubing hanger for the last phase of this procedure, and the equipment and techniques involved in utilizing it.

Each of the underwater completion tubing hangers known to the industry today presents one or more problems in their use. For example, the very high pressures sometimes encountered in offshore wells can be destructive of the hanger equipment if it should escape past the packings or seals. This is particularly true where, as is customary, the tubing hangers are supported by one or more casing hangers, which in turn find their support on the wellhead. Another problem with these prior devices is that they undesirably restrict the number of tubing strings that can be included in a given size hanger, thus requiring larger and more expensive equipment to achieve a result that a smaller hanger should facilitate. Many of the known hangers require the use of a considerable number of tools to manipulate them, several trips to accomplish their installation, and they sometimes fail to provide a positive lock-down indication. Yet another problem with the use of prior hangers is their lack of flexibility to accomodate various numbers of strings, i.e., they are designed for a given number and only that number can be handled.

SUMMARY OF THE INVENTION

Broadly considered, the present invention includes a pipe or tubing hanger assembly for a fluid producing well, a tool assembly for running and retrieving the hanger assembly, a tool assembly for completing the well and for running and retrieving one or more tubing hanger couplings and the strings of tubing connected thereto, and the procedure involved in the foregoing. The tubing hanger assembly includes facilities to run, align and land all the tubing strings, pressure testing the hanger, and locking it down into the wellhead, all during one trip into the well. The tubing hanger running and retrieving tool assembly includes facilities to releasably connect the tool to the hanger, land and lock the hanger into the wellhead, release its connection to the hanger, and for retrieval from the remotely located well. The completion and tubing hanger coupling running and retrieving tool assembly includes facilities to complete the well, to run and retrieve one or more preselected tubing strings from the surface to the tubing hanger, and also to retrieve any one or all of the tubing strings suspended in the well from the hanger.

The tubing hanger includes an inherently self-expandable support ring that functions to land and lock the hanger into the wellhead, releasable locking dogs to secure tubing hanger couplings in the hanger body, and a fluid test passage and port system to determine the integrity of the fluid seals between the hanger body and the couplings. The hanger running and retrieving tool assembly includes a clutch and mandrel nut that functions both to release the tool from the hanger and to power an actuator sleeve on the hanger to maintain the self-expanding support ring in its locking position. The completion and tubing hanger coupling running and retrieving tool assembly includes collet-type locking mechanisms for securing the tool to the tubing hanger couplings, rotatable mandrel subs to secure the collet fingers in their locking position, and positionable release rings for unlocking the tubing hanger couplings from the hanger body. The apparatus further includes alignment elements to properly align the tubing hanger assembly with the wellhead, the two tool assemblies with the hanger, and the connector device for coupling blowout preventers and a Christmas tree to the wellhead in proper position with respect to the tubing strings.

Accordingly, one object of this invention is to overcome each of the aforementioned problems associated with the use of prior tubing hangers apparatus, especially in underwater wells.

Another object of this invention is to provide a new single or multiple string tubing hanger apparatus that can be installed in the well in one trip.

Another object of this invention is to provide a new underwater completion tubing hanger apparatus that involves less parts, requires less tools and time for installation and removal, and is more versatile, flexible, and reliable than the presently available apparatus for this same general purpose.

Still another object of this invention is to provide a tubing hanger apparatus that, although designed particularly for use in underwater wells, is more proximate to the cost of land-based hanger equipment, especially in terms of time required to manipulate the hanger and the expense involved in its construction.

Yet another object of this invention is to provide a tubing hanger apparatus that is landed and locked directly to the well's casing head, rather than to a casing hanger as is the current practice, thereby transmitting all of the weight of the tubing string or strings directly to the casing head and providing a more secure suspension of the tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in elevation and in section of the tubing hanger assembly of this invention, attached to its running and retrieving tool assembly, and landed in the bore of a casing head constituting part of an underwater well completion system.

FIG. 2 is an enlarged view of the tubing hanger assembly taken along the line 2--2 of FIG. 1, showing the alignment dog for aligning the tubing hanger in the casing head.

FIG. 3 is a view taken along the line 3--3 of FIG. 1, showing the tubing hanger lockdown dogs in locking position with respect to the tubing hanger couplings.

FIG. 4 is a view taken along the line 4--4 of FIG. 1, illustrating the threaded engagement of the tubing hanger body with the alignment sleeve, and the lower fingered portions of the mandrel.

FIG. 5 is a view like FIG. 1, showing a portion of the tubing hanger assembly as it appears following the completion of the first phase of locking it into the casing head.

FIG. 6 is a view like FIG. 1, showing the tubing hanger assembly locked into the casing head, and the hanger running and retrieving tool assembly released from the tubing hanger assembly.

FIG. 7 is a view like FIG. 6, showing the tubing hanger assembly locked into the casing head, the completion and tubing hanger coupling running and retrieving tool assembly landed in, but not yet locked into, the tubing hanger assembly, and the tubing hanger coupling release rings in the upper or unlocked position.

FIG. 8 is an enlarged view of a portion of the apparatus illustrated in FIG. 7, showing the completion and tubing hanger coupling running and retrieving tool assembly locked into the tubing hanger assembly.

FIG. 9 is a view like FIG. 8, showing the completion and tubing hanger coupling running and retrieving tool assembly landed in, but not yet locked into, the tubing hanger assembly, and with the coupling release rings in the lower or locked position.

FIG. 10 is a view like FIG. 9, showing the completion and tubing hanger coupling running and retrieving tool assembly locked into the tubing hanger assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As stated previously, the apparatus of this invention comprises a tubing hanger assembly, a tubing hanger running and retrieving tool assembly, and a completion and tubing hanger coupling running and retrieving tool assembly, these assemblies interrelated such that the tubing string or strings can be run into the well and locked and sealed to the well head, and can be retrieved from the well head, with a minimum of procedural steps and during only one round trip into the well. The currently preferred form of the apparatus is illustrated in the drawings, and although the following description is directed primarily to these drawings it is to be understood that they are illustrative of but merely one form the invention can take. For example, instead of a dual tubing completion system as shown in the drawings, the invention can be used just as well with single, triple, quadruple or other multiple completions. Thus, the following description is not to be construed as limiting the invention to a dual completion system, but rather as an exemplification of one style of system in which the invention can be implemented.

FIGS. 1 through 6 illustrate the tubing hanger assembly and the tubing hanger running and retrieving tool assembly of this invention, and it is in conjunction with these Figures that these two assemblies will be described. With reference to FIGS. 1 through 4, the tubing hanger assembly 20 comprises a generally cylindrical tubing hanger body 22, a resilient self-expandable support ring 24, and alignment sleeve 26, a mandrel 28, a mandrel actuator sleeve 30, a pair of lockdown dogs 32, and an alignment dog 34. In this embodiment of the invention, the tubing hanger body 22 has a pair of bores 22a for receiving and supporting a pair of tubing hanger couplings 36, 38, the couplings have upper annular shoulders 36a, 38a that land and seat upon the hanger body's upper shoulders 22b, and lower annular shoulders 36b, 38b that similarly land and seat upon the hanger body's lower shoulder 22c. The lower ends of the tubing hanger couplings 36, 38 have internal threads 36c, 38c for connecting to the upper exteriorly threaded ends of a pair of tubing strings 40, 42, thereby providing support for these tubing strings in the tubing hanger body 22.

The upper end of each of the tubing hanger couplings 36, 38 has an exterior annular groove 36d, 38d for receiving the lower portion of one of a pair of lockdown dogs 32, when the couplings are seated in the tubing hanger body 22 and the lockdown dogs are in their extended or locking position as illustrated in FIGS. 1 and 3. In this position, the upper portions of the lockdown dogs 32 extend over the end surface of the tubing hanger couplings 36, 38, thus ensuring a secure lock of the tubing hanger couplings into the tubing hanger body 22. Each of the lockdown dogs 32 is biased into its extended or locking position by a spring assembly 44, which comprises an outer helical spring 44a surrounding an inner helical spring 44b, and each of these spring systems 44 is backed up by a lockdown dog cover 32a that is welded or otherwise fixed to the tubing hanger body 22.

For purposes of providing a fluid tight seal between the tubing hanger couplings 36, 38 and the tubing hanger body 22, each of the couplings is provided with three annular O-rings or similar packings 46, 48, 50. The lower portion of the tubing hanger body 22 likewise is provided with an annular packing 53 to establish a fluid tight seal between the tubing hanger body and the adjacent wellhead, which in this embodiment is the casing head 54. Thus, when the tubing hanger body 22 and the hanger couplings 36, 38 are landed, a fluid tight barrier exists between the casing head and each of these couplings.

One of the important features of the present invention involves the apparatus and procedure for aligning, landing, supporting and locking the tubing hanger body in the casing head 54. This apparatus includes the tubing hanger assembly's support ring 24, alignment sleeve 26, mandrel 28, mandrel actuator sleeve 30, and alignment key 34, all of which are acted upon in some manner by the tubing hanger running and retrieving tool assembly 60. This tool assembly 60 comprises a body 62, a clutch and mandrel nut 64, an annular resiliently expandable and contractable locking ring 66, an annular snap ring 68, and an annular packing element 70.

The tool body 62 has interior drill pipe threads at its upper end, these threads providing a means of connection to the end of a drill pipe 72 that is used to run and retrieve this tool assembly, and also to rotate it to align the hanger assembly 20, and lock and unlock the hanger body 22 in the casing head 54. This tool body 62 also is provided with acme threads about its exterior surface that cooperate with complementary threads 64a in the bore of the clutch and mandrel nut 64 to move the nut axially along the body 62, as will be described later in more detail. The tool body 62 has an upwardly facing, outwardly extending stop shoulder 62b, and the lower portion of the clutch and mandrel nut 64 has an opposed downwardly facing stop shoulder 64b, these stop shoulders functioning to restrict axial movement of the locking ring 66 on the body 62 when the tool assembly 60 is locked to the tubing hanger assembly 20 as illustrated in FIG. 1. In this locked condition, the locking ring 66, which is inherently biased towards its contracted state, is held in the illustrated expanded state by the nut's mandrel portion 64c, so that when the tool assembly 60 is landed in the bore 22m at the upper end of the tubing hanger body 22, the locking ring 66 extends into an inner annular groove 72 in the bore 22m, thereby locking the running and retrieving tool assembly 60 to the body 22, and hence also to the tubing hanger assembly 20. The annular packing 70 provides a fluid tight seal between the tool assembly body 62 and the tubing hanger body 22, so that in the locked condition, illustrated in FIG. 1, fluid tight integrity is established between the casing head 54 and the drill pipe 72.

The support ring 24 is split axially, is inherently self-expandable, and is under constant bias towards its expanded state illustrated in FIG. 1. The support ring 24 includes a plurality of upwardly extending circumferentially spaced fingers 24a with upper portions 24b and lower portions 24c. Each of the upper portions 24b includes an outwardly extending, downwardly facing stop shoulder 24d, and a generally upwardly and outwardly facing inclined camming surface 24e. The lower portion 24c of the support ring fingers includes a generally downwardly and outwardly facing cam surface 24f and a generally upwardly and outwardly facing cam surface 24g. The casing head 54, or other wellhead element designed for receiving and supporting the tubing hanger assembly 20, includes an inner annular groove 54a for receiving the lower portion 24c of the support ring fingers, and an inwardly extending, upwardly facing support shoulder 54b providing a seat for the support shoulder 24d of the support ring.

The support ring 24 is retained in position on the tubing hanger assembly 20 by an upwardly facing, outwardly extending shoulder 22f near the lower end of the tubing hanger body 22, and an annular recess 26a in the lower end of the alignment sleeve 26. As is best shown in FIG. 4, the alignment sleeve 26 is provided with internal threads 26b that engage external threads 22g on the tubing hanger body 22, so that the alignment sleeve and the tubing hanger body are joined together against relative axial movement. Consequently, although the support ring 24 is free to expand or contract, it cannot move axially on the tubing hanger body 22. Thus, when the tubing hanger assembly 20 is lowered into the casing head 54 until the support ring 24 is opposite the groove 54a, the ring expands into the groove, thereby positioning the stop shoulder 24d on the stop shoulder 54b, and precluding further downward movement of the ring, and hence the remaining elements of the tubing hanger assembly 20, in the casing head 54.

Although in the condition shown in FIG. 1 the tubing hanger assembly 20 is landed in the casing head 54, and thus cannot move further downwardly therein, the entire assembly 20 can be withdrawn from the casing head by simply lifting up on the drill pipe 72. As the assembly 20 begins to move upwardly, the support ring's cam surface 24g will cam the ring inwardly out of the groove 54a, freeing the ring and thus the assembly 20 from the casing head. This camming action will also occur as the surface 24e comes in contact with any obstructions further up the wellhead or conductor pipe, such as the lower end of the sealing sleeve 74 in the bore of the wellhead connector apparatus 76.

In order to lock the tubing hanger assembly 20 into the casing head 54, the support ring 24 is held in its expanded state (FIG. 1) by the mandrel 28. Looking at FIGS. 1 and 4, it is observed that the mandrel 28 comprises an upper annular portion 28a from which depend a plurality of circumferentially spaced fingers 28b that extend downwardly through axial grooves 22h in the outer surface of the tubing hanger body 22. The inner surface of the mandrel's annular portion 28a and approximately the upper half of each of the fingers 28b are provided with right hand acme threads 28c that engage complementary external acme threads 30a on the lower portion of the mandrel actuator sleeve 30. The upper end of the mandrel actuator sleeve includes a pair of diametrically positioned axial slots 30b that receive a correspondingly positioned pair of keys 64d formed in the upper portion of the clutch and mandrel nut 64. The mandrel actuator sleeve's lower end 30c abuts a shoulder 22j on the tubing hanger body 22, and the upper portion of the mandrel actuator sleeve has a reduced diameter to provide a stop shoulder 30d which abuts an inwardly extending, downwardly facing stop shoulder 26d on the alignment sleeve 26. Thus, in its assembly condition as illustrated in FIG. 1, the mandrel actuator sleeve is precluded from axial movement with respect to the tubing hanger body 22. Accordingly, when the clutch and mandrel nut 64 is rotated to the left, it carries with it the mandrel actuator sleeve, and this left hand rotation of the mandrel actuator sleeve causes the mandrel 28 to move downwardly from its position illustrated in FIG. 1 into its locking position inside or behind the support ring 24, as illustrated in FIG. 6, thereby preventing contraction of the support ring and effectively and securely locking the tubing hanger assembly into the casing head 54.

The foregoing described apparatus is, of course, installed in the casing head after the hole is drilled to completion depth and the various casing strings have been run. The following is an example of the procedure for accomplishing this installation when completing the well underwater from a drilling rig supported on a floating vessel, or on the ocean floor such as is commonly the case when drilling in shallow water. The well packers (not shown) and the tubing strings 40, 42 are run into the well bore, spaced out, and hung by slips in the rotary table at the drilling platform. The tubing hanger assembly 20, without the tubing hanger couplings 36, 38, is stripped over the tubing strings 40, 42. The tubing hanger couplings 36, 38 are then threaded onto the ends of the tubing strings 40, 42, and the competion and tubing hanger coupling running and retrieving tool assembly 100 (FIGS. 7 through 10) is attached to the tubing hanger couplings 36, 38 by a procedure to be described later. The slips on each tubing string are then removed, and the couplings 36, 38 are lowered into the tubing hanger assembly 20 until the stop shoulders 36b, 38b come to rest on the tubing hanger body stop shoulders 22c. As this occurs the springs 44 urge the lockdown dogs 32 inwardly into locking engagement with the couplings as illustrated in FIG. 1, thereby locking the couplings to the tubing hanger body. The slips are then reset on each tubing string 40, 42, and the coupling running and retrieving tool assembly 100 is removed. The pipe plugs 78 in the lower end of the tubing hanger body 22 are removed, a pressure test gun is attached to the tubing hanger body, and the pressure is applied to test the two seals 48, 50. Following the test, the gun is removed and the pipe plugs are reinstalled. A back pressure valve (not shown) is then installed in each tubing hanger coupling 36, 38.

The tubing hanger running and retrieving tool assembly 60 is made up on the drill pipe 72, and with the assembly in the released condition as shown in FIG. 5, i.e., with the clutch and mandrel nut 64 backed up against the snap ring 68, it is placed in the tubing hanger body bore 22m with the clutch and mandrel nut keys 64d engaging the actuator sleeve slots 30b. The tubing hanger running and retrieving tool assembly body 62 is then rotated to the right, such as by rotating the drill pipe 72, and because of the left handed thread system 62a, 64a, the clutch and mandrel nut 64 travels downwardly on the body 62, expanding the locking ring 66 into the groove 72 and thereby locking the tool assembly 60 to the tubing hanger assembly 20.

The tubing hanger assembly 20 is lowered into the well by the drill pipe 72 until the support ring's shoulder 24d lands on the casing head shoulder 54b. The hanger assembly 20 then is picked up approximately 1 foot (to prevent damaging any portion or part of the apparatus during alignment) and rotated to the right until the alignment key 34 springs out in response to its biasing springs 34a and catches in the groove 76a in the blow out preventer connector 76. The tubing hanger assembly 20 is then lowered until the support ring shoulder 24d again lands on the casing head shoulder 54b, thus placing the apparatus in the condition as shown in FIG. 1. The blow out preventers (not shown) are closed on the drill pipe 72, and the tubing hanger assembly 20 is tested through the preventers' kill line (not shown). The primary seals 48 on hanger couplings 36, 38 are again tested since they are exposed to pressure through the ports 52 in the tubing hanger body 22. The test pressure is then bled off and the blow out preventer rams are opened.

The drill pipe 72 is then rotated to the left, and since the clutch and mandrel nut threads 64a are left handed the nut will move up the running and retrieving tool assembly body 62 until it comes to rest against the snap ring 68, i.e., into the position as illustrated in FIG. 5. Since the mandrel actuator sleeve threads 30a are right handed, and since the clutch and mandrel nut keys 64d are still engaged with the mandrel actuator sleeve slots 30b, further left hand rotation of the drill pipe 72 causes the mandrel actuator sleeve 30 to rotate to the left, driving the mandrel 28 down behind the support ring 24, thereby locking the tubing hanger assembly 20 into the casing head 54 as shown in FIG. 6. Since the upward migration of the clutch and mandrel nut 64 withdrew its mandrel portion 64c from behind the locking ring 66, this ring contracted against the surface of the running and retrieving tool assembly body 62, thereby releasing the body from the tubing hanger body 22. Hence, the running and retrieving tool assembly 60 now can be retrieved by simply lifting up on the drill pipe 72.

As is illustrated in FIGS. 1, 4 and 5, the alignment dog 34 is retained in a socket 80 in the outer surface of the alignment sleeve 26 by a plurality of roll pins 34b that extend from holes in the side of the socket into grooves 34c in the side surfaces of the dog 34. Thus the dog is free to move inwardly until it contacts the inner surface of the alignment sleeve socket 80, but is prevented from moving completely out of the socket by engagement of the pins 34b with the inner ends of the grooves 34c.

The alignment sleeve 26 has a vertical groove 26e extending upwardly from the upper end of the socket 80 to the upper end of the sleeve, as shown best in FIG. 2. This alignment groove 26e cooperates with an alignment key in the bore of the Christmas tree connector (not shown), or other component that is to be installed on the wellhead after installation of the tubing hanger assembly 20, to align this connector, etc. with the tubing hanger assembly and its tubing strings. The upper terminal portion of the groove 26e diverges outwardly on either side in order to provide a guide for the alignment key as the Christmas tree connector, etc. is rotated to position its alignment key in the groove 26e.

To complete the well following the installation of the tubing hanger assembly 20, or to service or retrieve one or more of the tubing strings 40, 42, the completion and tubing hanger coupling running and retrieving tool assembly 100 is employed. As illustrated in FIGS. 7 through 10, an assembly 100 for use with a dual string tubing hanger such as 20 comprises a body 102 with two axial bores 102e, 102f, an alignment key 104 for cooperation with an inner vertical groove 26f in the alignment sleeve 26 to align the body 102 with the sleeve as it is being installed therein, mandrel subs 106, 108 extending through the bores 102e, 102f for establishing a connection with each of the tubing hanger couplings 36, 38, mandrel sub stop rings 110, 112 surrounding the mandrel subs 106, 108 and fitting into first counterbores 102g, 102h near the lower end of the bores 102e, 102f, collets 114, 116 surrounding the mandrel subs 106, 108, respectively, and retained in place in the lower ends of the bores 102e, 102f by retainer rings 118, 120 that reside partially in grooves 102a, 102b in the bores and partially in grooves 114a, 116a about the upper ends of the collets, and coupling release rings 122, 124 releasably secured to the collets 114, 116, respectively, by set screws 126.

The mandrel subs 106, 108 have external threads 106a, 108a that engage internal threads 102c, 102d, respectively in the bores 102e, 102f, and external annular packings 128 are provided at the lower ends of the mandrel subs 106, 108 to affect a fluid tight seal between them and the tubing hanger couplings 36, 38 when they are installed therein. The upper end of each of the mandrel subs 106, 108 is threaded into a stop coupling 130, 132, respectively, which couplings are in turn threaded onto surface tubing strings 134, 136 that extend to the drilling or production platform. An O-ring or other annular packing element 138 is provided between the mandrel subs 106, 108 and the stop couplings 130, 132 to assure a fluid tight seal therebetween.

The outer surface of each of the collets 114, 116 has an upper annular groove 114b, 116b, and a lower annular groove 114c, 116c. These grooves serve as locking positions for the coupler release rings 122, 124. As is illustrated in FIGS. 7 and 8, when the coupling release rings are secured to the upper grooves 114b, 116b, they rest above the tubing hanger coupling lockdown dogs 32 when the tool assembly 100 is installed in the tubing hanger 20, and thus exert no influence on the position of the lockdown dogs. However, when the release rings are secured to the lower grooves 114c, 116c, as illustrated in FIGS. 9 and 10, when the tool assembly 100 is installed in the tubing hanger assembly 20 the release rings are opposite the lockdown dogs 32, and thus hold them in an outward or retracted position. Since the lockdown dogs 32 provide the only restriction against upper withdrawal of the tubing hanger couplings 36, 38 from the tubing hanger body 22, when the release rings are in the lower grooves the tubing hanger couplings, and of course the tubing strings 40, 42 attached thereto, can be withdrawn from the tubing hanger body 22. Hence, by selective positioning of the release rings 122, 124 on the collets, the tool assembly 100 can be used either to complete the well by locking the surface tubing strings 134, 136 into the locked couplings 36, 38, and hence into the tubing strings 40, 42, or to connect the strings 134, 136 to released couplings 36, 38 to withdraw the strings 40, 42 from the well.

To illustrate the foregoing, suppose that for servicing purposes it is desired to connect the surface tubing strings 134, 136 to the well tubing strings 40, 42, but not to remove these latter strings from the well. The tool assembly 100 is made up at the surface with the mandrel sub stop shoulders 106b, 108b spaced from the stop rings 110, 112, as shown in FIG. 7, and the release rings 122, 124 in their upper grooves or positions 114b, 116b, respectively. The tool assembly then is run into the wellhead by the tubing strings 134, 136, and as the enlarged lower ends of the collet fingers 114d, 116d encounter the upper ends of the tubing hanger couplings 36, 38 they are deflected inwardly to permit the continued downward movement of the tool assembly 100 into its landed position, i.e., wherein the bottom end surface of the tool assembly body 102 rests on the upwardly facing, inwardly extending shoulder 22k of the tubing hanger body 22. At this position, the collet fingers 114d, 116d are opposite the inner annular grooves 36e, 38e in the tubing hanger couplings. As the tool assembly 100 is lowered into the wellhead, the alignment key 104 will either land in the groove 26f and travel on down in that groove until the tool assembly body 102 comes to rest on the support shoulder 22k, or the key will land on the annular beveled end surface 26g of the alignment sleeve 26. If the key lands on the beveled surface 26g, the tool assembly 100 is rotated, such as by placing a bar between the tubing strings 134, 136 and applying rotational force thereto, until the key falls off the bevel 26g into the alignment groove 26f.

With the tool assembly 100 landed in the tubing hanger assembly 20 as illustrated in FIG. 7, each surface tubing string 134, 136 is rotated to the right, thereby also rotating the corresponding mandrel sub to which the string is attached. As the mandrel subs rotate, their threaded engagement with the bores 102e, 102f causes them to migrate upwardly until their stop shoulders 106b, 108b come to rest against the stop rings 110, 112. This upward migration of the mandrel subs 106, 108 positions their collet locking surfaces 106c, 108c behind the enlarged ends of the collet fingers 114d, 116d, thereby locking the fingers in the grooves 36e, 38e of the tubing hanger couplings, as shown in FIG. 8. In this condition, since the collet fingers preclude movement of the mandrel subs' stop shoulders 106d, 108d upwardly past their enlarged lower ends, the mandrel subs are effectively locked to the tubing hanger couplings, and hence the surface tubing strings 134, 136 are securely connected to the tubing strings 40, 42.

Once this connection has been achieved, the back pressure valves (not shown) can be removed from the tubing hanger couplings in order to set the packers and do whatever work is necessary on the well. The back pressure valves are then reinstalled in the couplings, and the tubing strings 134, 136 are rotated to the left, causing the mandrel subs to move downwardly in the tool assembly body 102 and the hanger couplings 36, 38 until the surfaces 106c, 108c are not longer behind the lower ends of the collet fingers 114d, 116d. This frees the collet fingers to move inwardly out of the grooves 36e, 38e of the tubing hanger couplings, and the entire tool assembly 100 can then be removed from the wellhead merely by lifting on the surface tubing strings 134, 136.

As has been previously mentioned, it is also possible to retrieve the lower tubing strings 40, 42 from the well with the tool assembly 100, merely by positioning the coupling release rings 122, 124 in the lower grooves 114c, 116c on the collets 114, 116, respectively. This position change is facilitated by releasing the set screws 126, sliding the rings into the other position, and retightening the screws. Again referring to FIGS. 9 and 10, with the release rings secured to the lower position or grooves, as the completion tool assembly body 102 approaches the support surface 22k the rings cam the lockdown dogs radially outwardly, thereby unlocking the hanger couplings from the tubing hanger assembly body 22. Thus, when the mandrel subs have been rotated into their locked position with respect to the tubing hanger couplings (FIG. 10), the tubing strings can be retrieved from the well by lifting up on the completion tool assembly 100.

As will be readily apparent, the apparatus of this invention facilitates running and retrieving a single tubing string as well as a plurality of strings. Depending upon which string or strings in a multiple string system is to be connected into, the corresponding surface tubing string is connected to the tool assembly 100. Furthermore, in the multiple string system it is of course not necessary to couple or connect all of the several surface tubing strings to the lower tubing strings, if such is not desired.

As will be appreciated from the foregoing description, the apparatus of this invention provides many advantages. For example, there are no threads to be stabbed together and made up under water, thereby increasing reliability and reducing damage susceptibility of the hanger and running tools, all of which saves valuable rig time. Another advantage lies in the fact that since the expanding hanger lands on its own seat in the head, the tubing load and test pressure load is applied to the head directly rather than to the casing hangers or pack-offs below these hangers. This eliminates adding an additional load on the critical lower support shoulder in the bottom of the head.

Another advantage with the apparatus of this invention is that multiple strings of tubing may be run simultaneously on drill pipe in one trip. Furthermore, the complete hanger assembly can be run, aligned, packed off, tested and locked down all during this single trip.

Since each tubing string is on its own individual tubing hanger coupling, and each coupling is individually locked down in the tubing hanger body, running and/or retrieving individual tubing strings is possible, as well as individually locking and unlocking of the coupling for testing purposes. Since there are no threads in the top of the couplings to be damaged, reliability also is enhanced with the apparatus of this invention.

When all of the tubing strings are run at one time, the primary seals on each tubing hanger coupling can be tested at the surface. This is a very important feature of the present invention, since it not only indicates what seal is leaking on which tubing hanger coupling, but it also saves at least one trip into the hole with the hanger if the seal is leaking.

The use of the completion tool assembly 100 with the tubing hanger assembly 20 saves many valuable hours of rig time, since it allows removal and installation of the back pressure valves, setting of the packers, washing out the well, and any of the work required in each tubing string. Furthermore, each of the different pay zones may be flowed through this tool assembly. All information and condition of each pay zone can be determined, and if there are any problems they can be worked out before the Christmas tree is run and the flow lines connected.

Another important feature of this invention is that all functions performed by the tubing hanger assembly 20 and the other tools are mechanical, and are independent of up and down motion of the drilling or production platform. The apparatus of this invention is economical to manufacture, is of comparatively simple design, and is ruggedly built to withstand the hammer effect of this up and down movement, particularly while landing the tubing and the tools. All of this increases the reliability of the equipment and reduces the damage thereto, thus saving valuable rig time.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

Claims

We claim:

1. A well pipe hanger assembly for suspending one or more strings of pipe in a fluid-producing well, comprising

a. a generally cylindrical hanger body having at least one axial bore therethrough, said body having upper and lower ends with said upper end adapted for releasable connection to a well tool;

b. a resilient, self-expandable hanger support ring circumscribing said hanger body and carried thereon for free radial movement between contracted and expanded positions;

c. mandrel means for locking said hanger support ring in its expanded position;

d. mandrel actuator means for moving said mandrel means into its hanger support ring locking position;

e. means for aligning said hanger assembly;

f. pipe coupling means seated in said hanger body and releasably secured against upward movement therefrom;

g. fluid seal means between said hanger body and said pipe coupling means;

h. means in said hanger body for testing the integrity of said seal means before said hanger assembly is installed in an outer pipe element; and

i. means in said hanger body for testing the integrity of said seal means after said hanger assembly is installed in said outer pipe element.

2. A pipe hanger assembly according to claim 1 wherein said mandrel actuator sleeve includes means for releasably and non-rotatably connecting said sleeve to a well tool, and wherein said mandrel means is moved into its hanger support ring locking position by rotation of said well tool and said mandrel actuator sleeve.

3. A pipe hanger assembly according to claim 2 wherein rotation of said well tool also releases its connection to said hanger body.

4. A pipe hanger assembly according to claim 1 wherein said aligning means comprises an alignment sleeve circumscribing said hanger body and an alignment key biased outwardly from said alignment sleeve, said alignment key cooperating with an outer pipe element to permit rotation of said hanger assembly in that pipe element until said assembly is aligned therein, and then to preclude further rotation of said alignment sleeve and said hanger body.

5. A pipe hanger assembly according to claim 4 wherein said alignment sleeve is threadedly connected to said hanger body, and said mandrel comprises a ring-like body portion and a plurality of circumferentially-spaced fingers depending therefrom, said fingers extending between said alignment sleeve and said hanger body in grooves positioned longitudinally in said hanger body.

6. A pipe hanger assembly according to claim 1 including a releasable connection between said hanger body and said well took, said connection comprising a split-ring locking element, a ring-expanding mandrel, and an annular groove into which said locking element can be expanded.

7. A pipe hanger assembly according to claim 6 wherein said split-ring locking element and said ring-expanding mandrel are components of said well tool, said hanger body includes a centrally positioned bore in its upper portion, and said annular groove is located in said centrally positioned bore.

8. A pipe hanger assembly according to claim 1 wherein said mandrel actuator means comprises a rotatable sleeve circumscribing said hanger body and threadedly engaging said mandrel means, said sleeve including at least one slot in its upper end to accommodate a key fixed to said well tool.

9. A pipe hanger assembly according to claim 1 wherein said aligning means includes means for accepting and aligning an outer well completion element with said hanger assembly, and means for accepting and aligning an inner well completion and servicing tool.

10. A well tool assembly for running and retrieving a well pipe hanger assembly, comprising

a. an annular body with an upper section adapted for connection to a pipe string, a lower section adapted for releasable connection to said hanger assembly, and an intermediate section with external threads for moving a circumscribing tool element axially thereon;

b. an annular clutch and mandrel means circumscribing said body, said means including internal threads complementary to said external threads on said body, a mandrel section for preventing contraction of an annular element against said body, and means for releasably engaging a rotatable pipe hanger element to cause said element to rotate in concert with said well tool;

c. an annular resiliently expandable and contractible locking element surrounding said body; and

d. first and second stop means spaced axially on said body for restricting axial movement of said clutch and mandrel means on said body to a predetermined area,

whereby when said clutch and mandrel means is threadedly engaged with said body and releasably engaged with said pipe hanger element, rotation of said body will cause said clutch and mandrel means to move axially on said body, to release said annular locking element for contraction, and to rotate said pipe hanger element.

11. A well tool assembly according to claim 10 wherein rotation of said body causes said clutch and mandrel means first to move axially into contact with said second stop means, and then to rotate with said body.

12. A well tool assembly according to claim 10 wherein said first stop means comprises an annular shoulder on said body, said second stop means comprises a snap ring residing in an external annular groove on said body, and wherein said clutch and mandrel means includes a pair of keys for engaging complementary slots in said rotatable pipe hanger element.

13. A well tool assembly, comprising

a. a generally cylindrical body having at least one axial bore therethrough, said body having upper and lower ends with said lower end adapted for cooperatively engaging a well pipe hanger assembly;

b. at least one mandrel sub rotatably extending through a bore in said body and threadedly engaged therewith;

c. means for releasably connecting said mandrel sub to a pipe coupling in said pipe hanger assembly and

d. means for selectively releasing said pipe coupling from said pipe hanger assembly to facilitate removal of said coupling from said assembly.

14. A well tool assembly according to claim 13 including means for aligning said well tool assembly with said pipe hanger assembly.

15. A well tool assembly according to claim 13 wherein said connecting means comprises a collet with flexible fingers, said collet circumscribing said mandrel sub and secured to said body.

16. A well tool assembly according to claim 15 wherein said collet has enlarged portions on its flexible fingers for engaging an internal annular groove in said pipe coupling, and said mandrel sub includes a locking surface for locking said enlarged finger portions into said pipe coupling's annular groove.

17. A well tool assembly according to claim 13 wherein rotation of said mandrel sub in said body, when said tool assembly is properly positioned with said pipe hanger assembly, locks said mandrel sub to said pipe coupling.

18. A well tool assembly according to claim 13 wherein said selectively releasing means comprises a ring-like element circumscribing said mandrel sub and selectively positionable in a locking and an unlocking location with respect to the pipe coupling.

19. A tool assembly according to claim 13, including a plurality of bores through said body, a mandrel sub in at least one of said bores, a collet for locking said mandrel sub to a pipe coupling, and a multi-positionable release ring for selectively releasing said pipe coupling from said pipe hanger assembly.

20. A well tool assembly, comprising

a. a generally cylindrical body having at least one axial bore therethrough, said body having upper and lower ends with said lower end adapted for cooperatively engaging a well pipe hanger assembly;

b. at least one mandrel sub rotatably extending through a bore in said body and threadedly engaged therewith; and

c. means circumscribing said mandrel sub and secured to said body for releasably and non-threadedly connecting said mandrel sub to a pipe coupling in said pipe hanger assembly as said mandrel sub is rotated.

21. A well tool assembly according to claim 20 including means for aligning said well tool assembly with said pipe hanger assembly.

22. A well tool assembly according to claim 20 wherein said connecting means comprises a collet with flexible fingers.

23. A well tool assembly according to claim 22 wherein said collet has enlarged portions on its flexible fingers for engaging an internal annular groove in said pipe coupling, and said mandrel sub includes a locking surface for locking said enlarged finger portions into said pipe coupling's annular groove.

24. A well tool assembly according to claim 20 wherein rotation of said mandrel sub in said body, when said tool assembly is properly positioned with said pipe hanger assembly, locks said mandrel sub to said pipe coupling.

25. A well tool assembly according to claim 20 wherein said selectively releasing means comprises a ring-like element circumscribing said mandrel sub and selectively positionable in a locking and an unlocking location with respect to the pipe coupling.

26. A tool assembly according to claim 20, including a plurality of bores through said body, a mandrel sub in at least one of said bores, a collet for locking said mandrel sub to a pipe coupling, and a multi-positionable release ring for selectively releasing said pipe coupling from said pipe hanger assembly.

27. A well apparatus comprising, in combination

a. a well pipe hanger assembly;

b. means attachable to said well pipe hanger assembly for running said assembly into a wellhead element;

c. means secured to said well pipe hanger assembly for aligning said assembly with said wellhead element;

d. means secured to said well pipe hanger assembly for landing said assembly in said wellhead element;

e. means secured to said well pipe hanger assembly for locking down said assembly in said wellhead element; and

f. means in said well pipe hanger assembly for testing the integrity of fluid-tight seals that are established between said assembly and well pipe when said well pipe is hung in said assembly, said well apparatus facilitating running, aligning, landing, locking down and testing said well pipe hanger assembly in one trip into the well.