Embedded flex-lock slip liner hanger

A liner hanger includes an annular slip seat that radially surrounds a section of the liner being hung. The slip seat contains a plurality of windows that each accommodates at least one intermediate slip seat. The intermediate slip seats, in turn, each contain windows that accommodate a slip element. There are tongue and groove arrangements between the slip seat and the intermediate slip seat as well as between the intermediate slip seat and the slip element that allow axial movement of the slip element to be translated by camming surfaces into radial outward movement of both the intermediate slip seat and the slip element. The imposition of one or more intermediate slip seats, in an embedded or nested relationship, allows for greater radial expansion of the slip elements with respect to the interior liner.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the design of anchoring slip assemblies and, in particular aspects, to the design of liner hanger devices used for suspending a liner within a wellbore.

2. Description of the Related Art

A liner is a tubular member that is usually run inside of wellbore casing and suspended within it. 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 regard to the liner hanger mandrel. As the slips are translated axially, they are cammed radially outwardly by a ramped surface that is fashioned into the mandrel. As the slips move radially outwardly, toothed outer surfaces of the slip will bitingly engage the surrounding casing. This type of arrangement is shown, for example, in U.S. Pat. No. 4,497,368 issued to Baugh, wherein slips that are radially expanded by riding up over cone elements fashioned into the tubular body of the central mandrel. U.S. Pat. No. 5,086,845 issued to Baugh and U.S. Pat. No. 6,431,277 issued to Cox et al. each describe a hanger arrangement wherein load is transferred circumferentially through the slip seat. U.S. Pat. Nos. 4,497,368, 5,086,845, and 6,431,277 are all owned by the assignee of the present invention and are incorporated herein by reference.

A problem with this standard slip setting arrangement is that the amount of radial expansion of the slip elements is limited. The depth of the slip ramp, and thus the amount of camming, is largely limited by the thickness of the slips and slip seat in the mandrel body. These thicknesses are close to the same, with the slips usually being slightly thinner than the slip seat so that the teeth of the slips will not be exposed over the slip seat when the slip is not set. If the needed camming distance is defined as the distance between the outer diameter of the tool and the inner diameter of the casing to hang in, then it is entirely limited by the thickness of the slip. The slip, in turn, is limited in thickness by the stipulation that it rests on the mandrel body and should be thinner than the slip seat. This restriction can be broken by reducing the outer diameter of the portion of the mandrel over which the slips sit. However, this reduced outer diameter and mandrel thickness would result in a decreased pressure rating for the tool, which is undesirable.

A further limitation to camming distance relates to the mechanism used to retain the non-cammed end of the slip element in place upon the mandrel body. In U.S. Pat. No. 5,086,845, the slips are not restrained by any type of structure. However, an overlying tab was later introduced to hold the lower ends of slips in place. This tab arrangement also limits the setting distance of the slips by reducing the degree of freedom of movement that the slip elements have.

The present invention addresses the problems of the prior art.

SUMMARY OF THE INVENTION

The invention provides a liner hanger with an annular slip seat that radially surrounds a section of the liner being hung and is secured to the liner. The slip seat contains a plurality of windows that each accommodates at least one intermediate slip seat. The intermediate slip seats, in turn, each contain windows that accommodate a slip element. There are camming arrangements between the slip seat and the intermediate slip seat as well as between the intermediate slip seat and the slip element that cause axial movement of the slip element to be translated into radial outward movement of both the intermediate slip seat and the slip element. In a presently preferred embodiment, the camming arrangement is a tongue-and-groove arrangement. The imposition of one or more intermediate slip seats, in an embedded or nested relationship, allows for greater radial expansion of the slip elements with respect to the interior liner. This increased radial expansion allows for the liner hanger to be set within a greater range of casing I.D.s. Additionally, the liner hanger can have a more secure set due to the increased radial expansion range.

Another aspect of the present invention provides an improved linkage between the slip element and the setting sleeve that allows pivoting movement between the slip elements and the setting sleeve. The pivoting linkage better accommodates the increased radial setting distance afforded by the use of intermediate slip seat(s).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2depict an exemplary embedded slip-lock liner hanger10, which is constructed in accordance with the present invention. The liner hanger10is shown radially surrounding a tubular liner12that will be secured within a surrounding casing (not shown) by the liner hanger10. The liner12defines an axial flowbore14along its length for transport of fluids.

The upper end of the liner hanger10features a primary slip seat16that is fixedly secured to the liner12by threaded connection18. The primary slip seat16includes an upper axial end20and lower axial end22. A plurality of angular windows24is cut into the primary slip seat16in a spaced relation about the circumference of the primary slip seat16. The number of windows24may vary depending upon the number of slips that it is desired to include on the liner hanger10. Each of the windows24have a pair of sidewalls26that converge as they approach the upper end28of the window24. Additionally, each sidewall26contains a groove30that angles radially outwardly as it approaches the upper end28of the window24.

An intermediate slip seat34is moveably disposed within each of the windows24. The intermediate slip seat34is shown apart from the other components of the liner hanger10inFIG. 5 and 6. The intermediate slip seat34includes a generally wedge-shaped seat body36that has a central window38cut therein. The central window38includes sidewalls40that converge as they approach the upper end42of the seat body36. Angled grooves44are formed into the sidewalls40. Below the central window38is a link recess46that extends from the central window38to the lower end48of the seat body36. Tongues50extend from each lateral side52of the seat body36. The tongues50are shaped and sized to be slidably received within the grooves30of the slip seat16. The tongue-and-groove relationship allows axial movement of the intermediate slip seat34with respect to the primary slip seat16. The intermediate slip seat34is moved radially outwardly via camming action upon the outer camming surface35of the sidewalls26. Those of skill in the art will understand that other suitable camming arrangements might be used as well, such as inclined planes (i.e, ramps) to perform the function of urging the intermediate seat34radially outwardly upon axial movement of the intermediate seat34.

A slip element54is disposed within the window38of each intermediate seat34. An exemplary slip element54is depicted apart from the other components of the liner hanger inFIGS. 3 and 4. The slip element54features a generally wedge-shaped slip body56that is shaped to reside within the central window38of the intermediate seat34. A number of engagement teeth58extend from the slip body56for forming a biting engagement with a surrounding casing or liner. Tongues60extend laterally from the sidewalls62of the slip body56and are disposed within the grooves44of the intermediate slip seat34. This tongue-and-groove relationship allows axial movement of the slip element54with respect to the intermediate slip seat34. In addition, the outer camming surface55associated with the grooves44will cam the slip element54outwardly. Again, those of skill in the art will understand that other suitable camming arrangements might be used as well, such as inclined planes (i.e., ramps) to perform this same function. A hinge portion64extends from the lower end66of the slip body56.

As shown inFIGS. 1 and 2, link members68extend from each hinge portion64to a setting sleeve70. Each of the link members68is interconnected with both the hinge portion64and the setting sleeve70by pivot pins72, which permit pivoting movement of the link members68with respect to both the hinge portion64and the setting sleeve70.

In operation, the setting sleeve70is moved axially by one of several well-known methods, including hydraulic pressure actuation. U.S. Pat. No. 5,086,845 describes details of one type of hydraulic pressure actuation in detail. As the setting sleeve70is moved axially upwardly with respect to the liner12, it is translated from its lower unset position, shown inFIG. 1, to an upper set position, shown inFIG. 2. The slip elements54are urged upwardly as well. Upward movement of the slip elements54results in the slip elements54being moved radially outwardly as well, due to the sliding, camming action upon camming surfaces55associated with grooves44. In addition, the intermediate slip seats34will be moved axially upwardly and radially outwardly with respect to the slip seat16due to camming action of the slip seats16upon camming surfaces55associated with grooves30. Due to the nesting, or embedding, of the slip elements54within the intermediate slip seats34and further nesting, or embedding, of the intermediate slip seats34within the windows26of the primary slip seat16, the slip elements54are moved radially outwardly to a greater extent than with prior art arrangements.

A slip element54, intermediate slip seat34and window24generally collectively form a single slip assembly74. There are typically multiple slip assemblies74incorporated into a liner hanger10. Currently preferred embodiments for liner hangers constructed in accordance with the present invention include three or more slip assemblies74. However, the invention is not limited to any particular number of slip assemblies.

The described embodiment shows a single intermediate slip seat34that is nested between the slip element54and the slip seat16. It will be understood however that, for any particular slip assembly74there may be multiple intermediate seats similar to intermediate slip seat34. These would be embedded or nested within one another and each able to move axially and radially with respect to each other.

The liner hanger10provides the advantage of providing a greater radial setting distance for the slip elements54. This greater setting distance is provided by the presence of the intermediate slip seat34, which is itself radially extended out from the primary slip seat16during setting. Thus, the additional radial setting distance provided by the intermediate slip seat34is the approximate thickness of the intermediate slip seat34. Additionally, the pivoting linkage between the setting sleeve70and the hinge portion64of each slip element54better accommodates the increased setting range of the slip elements by allowing freer movement of the slip elements54.

Those of skill in the art will recognize that numerous modifications and changes may be made to the exemplary designs and embodiments described herein and that the invention is limited only by the claims that follow and any equivalents thereof.