1. Field of Invention
The invention is directed to couplers or collars having one or more axially movable slips disposed therein for connecting oil and gas well casing and for hanging a liner within the casing and, in particular, to couplers having the slip initially disposed behind a moveable cover that is moved to permit setting of the slip.
2. Description of Art
A liner is a tubular member that is usually run inside of wellbore casing of an oil or gas well and suspended within the wellbore casing. Liners are typically secured within a wellbore by toothed slips that are located on liner hangers. The slips are set by axially translating them with respect to the liner hanger mandrel or housing. As the slips are translated axially, they are cammed radially outward by a ramped surface that is fashioned into the mandrel. As the slips move radially outward, the toothed surfaces of the slip will bitingly engage the inner wall surface of the wellbore casing. This type of arrangement is shown, for example, in U.S. Pat. No. 4,497,368 in which slips are radially expanded by riding up over cone elements disposed into the tubular body of the central mandrel.
Actuation systems for such slips in the past employed full circumference hydraulically actuated pistons to move the slips. These designs presented a pressure rating problem in that the full circumference piston frequently had a maximum working pressure significantly lower than the mandrel which it surrounded. Thus, this type of design limited the maximum working pressure in the string to the rating of the cylindrical piston housing assembly. For example, it was not unusual in prior designs to have mandrels rated for 12,000 PSI while the surrounding cylinder housing for the cylindrical piston to only have a rating of approximately 3,000 PSI.
In an effort to improve the shortcoming of this design, another design illustrated in U.S. Pat. No. 5,417,288 was developed. In this design the mandrel body received a pair of bores straddling each of the slips. A piston assembly was mounted in each of the bores with all of the necessary seals. The application of hydraulic pressure in the mandrel into all the piston bores actuated the pistons on either side of each slip through a common sleeve to which all the slips were attached. This design, however, was expensive to manufacture, had many potential leak paths in the form of the ring seals on each of the pistons wherein each slip required two pistons.
On the other hand, this design provided for a higher pressure rating for the liner hanger body and also used the hydraulic pressure directly to actuate the slips. Necessarily, it did not include a locking feature against premature slip movements due to inadvertently applied pressures. The design in U.S. Pat. No. 5,417,288 also did not provide for flexibility for changed conditions downhole which could require additional force to set the slips. In essence, each application was designed for a pre-existing set of conditions with field variability not included as a feature of that prior art design.
These prior liner hangers also required use of devices and structures that increase the overall outer diameter of the liner hanger. Therefore, these liner hangers result in a reduction of usable diameter within the well. This is because the liner hanger is carried by the liner which requires the liner to be of a smaller diameter than the casing against which it is set or hung. The liner is then set within the annular space between the liner and the casing. Once set, the useable diameter of the well (i.e., the diameter through which production fluid can flow or tools can be passed) becomes the inner diameter of the liner. However, the components of the device securing the liner within the casing (including slips, elastomeric seals, setting sleeves and so forth) inherently occupy space between the liner and casing. For example, a wellbore having standard 21.40 lb. casing with an outer diameter of 5 inches, would have an inner diameter of 4.126 inches. It would be desirable to run into the casing a string of tubing, i.e., a liner, having an outer diameter of approximately 4 inches, which would allow for a liner with a large cross-section area for fluid flow and tool passage. However, the presence of the liner setting components on the outside of the liner will dictate that a smaller size liner or tubing string (such as 2⅞ inches) be run. Over an inch of diameter in usable area is lost due to the presence of both the liner and the liner setting device that is set within the space between the liner and the casing.
With respect to the slip assemblies, in the past those slip assemblies also have been configured in a variety of ways. In one configuration, when the slips are actuated, the load is passed through the slips circumferentially through their guides or retainers and transmission of the load to the underlying mandrel is avoided. In other more traditional designs, the slips are driven along tapered surfaces of a supporting cone and the loading that is placed on the supporting mandrel is in a radial direction toward its center, thus tending to deform the mandrel when setting the slips. Typical of such applications are U.S. Pat. Nos. 4,762,177, 4,711,326 and 5,086,845.
In another prior attempt, illustrated in U.S. Pat. No. 6,431,277, the liner hanger has an actuating piston that releases a mechanical latch that is restraining a set of springs. Once the latch is released, the springs set the slips. The liner hanger in this patent is also designed with a separate spring housing that restricts the total number of springs that can be used and is difficult to assemble.
Liner hanger devices disclosed herein are directed to a coupler or collar for joining two pieces of oil or gas well casing. The coupler includes an enlarged inner diameter portion forming a pocket in the inner wall surface of the coupler. Slidingly engaged within the pocket is a slip. The slip is disposed behind a moveable cover that prevents the slip from setting until it is moved.
In use, the coupler secures together two pieces of casing. The casing is then run into the wellbore to the desired depth. Although not required, the casing can then be cemented into place.
An inner tubing, or liner, such as production casing is then run into the casing. The liner includes an actuator that is operatively associated with the cover. As the liner is lowered within the casing, the actuator actuates the cover so that the cover is moved from a first position in which the cover restricts movement of the slip to a second position in which the slip is capable of movement to its lower or set position in which the liner is secured within the casing.
Because the slip and cover are located within the pocket portion of the casing coupler, the liner can be set or hung within the casing while saving useable cross-sectional area within the casing. In the instance of the 5 inch casing situation described above in the Background section, a liner having a four inch diameter could be run into the exterior casing.
While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims.
Referring now to
Coupler 20 includes an outer wall surface 22 defining an outer diameter, housing 23, and inner wall surface 24 defining various inner diameters. Inner wall surface 24 includes recess or pocket 26 defined by a variable enlarged inner diameter between two smaller inner diameters—one above and one below. Shoulder 27 of pocket 26 is conical. As discussed below, the inner wall surface 24 of pocket 26 has differing shapes depending on the specific embodiment.
Slip 40 is disposed within pocket 26. Slip 40 includes first end 41 and second end 42. Slip second end 42 includes gripping member 46 having slip gripping profile 48 for engaging or biting into liner 52 being hung within wellbore 10. First end 41 is part of upper portion 44 which can be a single solid sleeve, a single partial sleeve, or a plurality of partial sleeves separated by vertical slots and disposed circumferentially around pocket 26.
Gripping member 46 is connected to setting mechanism 44 by connection member 45. The lower ends of gripping members 46 are tapered to mate with shoulder 27. Connection member 45 is a flexible or collapsible thin walled portion of slip 40 whose flexibility or collapsibility facilitates setting of slip 40. Connection member 45 may be a single thin walled sleeve, a single partial thin walled sleeve, or a plurality of thin walled strips or partial sleeves separated by vertical slots so that each gripping member 46 is connected to upper portion 44 of slip 40.
Gripping profile 48 may have wickers or any other configuration that facilitates gripping profile 48 to grip or bite into liner 52 being hung within casing 14. For example, gripping profile 48 may include teeth 50. Alternatively, gripping profile 48 may be profiled with grippers formed of carbide or other material, velcro material, ball bearings, or spray-on grit surfaces, or any other material that facilitates increased friction or provides surface penetration of the gripping profile 48 into liner 52. In one specific embodiment, gripping profile 48 is curved or concave, having the same curvature as the outer diameter of liner 52. In another specific embodiment, gripping profile 48 is a cam surface causing a camming motion against liner 52 to facilitate securing liner 52 to wellbore casing 14. In a particular embodiment, gripping profile 48 is angled such that upward movement of a structure, such as an outer wall surface of cover 80 along gripping profile 48, does not encourage or cause “biting” or “camming” of gripping profile 48 into the structure moving upward along gripping profile. To the contrary, downward movement or force by a structure, such as an outer wall surface of liner 52, encourages or causes “biting” or “camming” of gripping profile 48 into the structure.
Slip 40 is initially restricted from movement within pocket 26 by cover 80. Cover 80 comprises upper end 81, lower end 82, inner wall surface 83, and outer wall surface 84. As discussed in greater detail below, cover 80 has a first position in which slip 40 is restricted from movement to its set position and a second position in which slip 40 is capable of movement to its set position.
Referring now to
In the embodiment of
Recess 86 is engaged by an actuator, which in this embodiment is collet 60 disposed on sub 62, which is secured to two sections 64, 66 of liner 52. Alternatively, collect 60 may be secured directly to the outer diameter of a piece of liner such as through welding.
Collet 60 includes one or more outwardly biased fingers 68, each finger 68 having key or tab 70 for engagement within recess 86 of cover 80. Each finger 68 is forced inward by the inner wall surface of casing 14 and then by inner wall surface 83 of cover 80 during run-in of liner 52. When finger 68 is disposed opposite recess 86 by moving liner 52 downward within casing 14, the outwardly biased fingers 68 move outward so that keys 70 of fingers 68 are inserted into recess 86. After engagement of keys 70 into recess 54, cover 80 can be moved upward from its first position (shown in
In one embodiment, shown in
Initially, slip 40 is fully recessed within pocket 26. Because the components of cover 80 and slip 40 are retained within pocket 26 of casing coupler 20, the gap between the exterior of liner 52 and the interior of casing string 14 can be quite small. For example, in a casing string made up of 35.3 lb., casing sections with an external diameter of 5 inches, an interior diameter of 4.126 inches would be available. Thus, it would be possible to insert liner 52 having a diameter approximating 4 inches, rather than a smaller diameter liner such as one having a diameter of 2⅞ inches. As mentioned above, the use of a larger diameter liner 52 is desirable for two reasons. First, the resulting available cross-sectional flow and work bore area of liner 52 will be larger. Second, gripping member 46 of slip 40 can be more easily and securely held against the larger diameter liner 52.
Liner 52 is lowered within the housing bore of casing 14 and through the bore of coupler 20 until tabs 70 engage recess 86. Liner 52 is then lifted upward causing cover 80 to be moved upward until slips 40 are freed to move radially inward. In so doing, the stored energy within the downwardly biased member is released such that a downward force is exerted on slip flange 43 resulting in the downwardly biased member, (spring 49 in the embodiment of
Referring now to
In another embodiment illustrated in
Referring now to
As shown in
In one particular embodiment, the length of external helical threads 102 and internal helical threads 104 are such that slip 40 is released from the mated connection of external and internal helical threads 102, 104 after cover 80 has been moved to its second position (
As with the embodiment shown in
As illustrated in
The outer wall surface of sleeve 30 forms a groove 32 with housing 23 into which slip 40 is disposed. Sleeve 30 includes a sleeve flange 34 at its lower end. Cover 80 is in sliding engagement with the inner wall surface of sleeve 30. Cover 80 has a large upper end or head so that chamber 36 is defined by cover 80 and sleeve 30. Cover 80 also comprises port 38 in fluid communication with chamber 36 and the housing bore. Seals, shown as elastomeric seals, but not numbered are disposed along cover 80, sleeve flange 34, and liner 52 to isolate chamber 36.
As shown in
The lower end of liner 52 is closed off by a plug (not shown). The plug is preferably a temporary or removable plug which can be removed, such as by milling, to allow flow through liner 52 at a later point during production operations. Ports 53 are disposed through the side of liner 52. Various seals (shown as elastomeric seals, but not numbered) are provided to isolate fluid communication between ports 53 and ports 38 when ports 53 are properly disposed within the housing bore.
In operation, cover 80 is initially in its first position (
Once secured within coupler 20 by slip 40 moving to its lower position (
Referring now to
Cover 80 comprises cover flange 87 disposed along outer wall surface 84 of cover 80. Cover flange 87 is in sliding engagement with the inner wall surface of slip 40 and, as shown, includes an elastomeric seal. As shown, cover 80 does not touch shoulder 27 in the first position (
The lower surface of slip flange 208 upper surface of cover flange 87, the inner wall surface of slip 40, and the outer wall surface of cover 80 define chamber 206. Recess 214 is inscribed in the inner wall surface of slip 40 within chamber 206. Also within chamber 206, stop ring 218 is fixedly secured to inner wall surface 216 of slip 40 and is, in turn, secured to a split ring, or C-ring member 220. Although stop ring 218 is shown in
In the first position (
Chamber 206 is at a lower pressure, e.g., atmospheric pressure, as compared to the hydrostatic pressure disposed directly below cover flange 87 so that there is a pressure differential across cover flange 87. The pressure differential urges cover flange 87 and, thus, cover 80, upward toward the second position (
In operation, cover 80 is initially in the first position and slip 40 is initially in the upper or unset position shown in
As also with other embodiments discussed herein, slip 40 may include slip flange 43 disposed on the outer wall surface of slip 40 to form chamber 47 having coiled spring 49 as shown in
It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. For example, a ratchet mechanism may be located within the pocket 26 and operatively associated with the slip, such as thorough the slip flange, to operate in the manner of a body lock ring to ensure one-way sequential movement of the slip with respect to the surrounding casing coupler 20. Such a ratchet mechanism may also be utilized with any of the other embodiments so that liner 52 cannot be removed from the slip by upward movement alone. Additionally, the coupler may have only one slip or a plurality of slips having a space between each slip. Moreover, the recess within cover may be a single continuous groove along the outer wall surface of the cover or it may be one or more short slots. Further, the slip may be a single sleeve component having one or more gripping members. Additionally, in the embodiment in which liner 52 includes one or more port 53, and seals may be disposed on cover 80 instead of on liner 52. Further, transmitter 224 may not be located on the liner, but instead transmitter 224 may be located elsewhere, such as on the casing string, in the coupler, or as part of the setting mechanism. In such an embodiment, transmitter 224 is activated from the surface of the wellbore after the liner is placed in its desired position within the casing. Additionally, the elastomeric seals shown, but not numbered, in several of the embodiments may be dynamic metal-to-metal seals or any other type of seal known in the art. And, the seals may be disposed at locations other than those illustrated in the Figures. In addition, the cover 80 can also comprises port that provides fluid communication between the wellbore of casing string 14 and the area disposed below cover flange 87 in the embodiment of