Insert seal units function to allow cementing accessories such as “landing collars”, “float collars”, “float shoes”, “drillable packoffs” and ball catcher subs to be installed directly into a line casing for installation in a wellbore. The insert seal units are configured to support any one of the identified accessories and to provide such support in a range of liner casing sizes. The seal units' capability of being sealably mounted in a range of casing sizes eliminates the need for specifically designed insert seal units for each casing size thereby rendering manufacture of the units more economical.
While commercially available insert seal units such as Baker Oil Tools part # H079721601 operate well for their intended function, they do suffer from long term degradation due to elastomer breakdown. The units typically rely upon an elastomeric O-ring seal that while providing a very good initial seal, will of course be detrimentally affected by the harsh environment of a wellbore. This is particularly true in a hydrocarbon wellbore due to high temperatures and harsh chemical constitution of environmental fluids. The art would of course appreciate the longevity of an insert seal unit having greater resistance to such environmental factors.
An insert seal unit includes a frustoconical body. A lower slip assembly is in operable communication with the body as is an upper slip. A seal element is in operable communication with each of the upper slip and the lower slip assembly.
Referring now to the drawings wherein like elements are numbered alike in the several Figures:
Referring to
Upon the outside surface 14, a recess 18 is disposed extending radially inwardly of the outside surface 14 in a roughly triangular cross-section (in the illustrated embodiment; other recess shapes are not precluded and are contemplated). Moreover, the recess may be annular or may be in segments that when viewed together from a transverse cross-section, appear annular in shape. It is to be appreciated that the geometry of the recess 18 is important in two aspects. The first is a frustoconical surface 20 and second is a bearing surface 22. The frustoconical surface 20 is so shaped in a direction opposite to the direction of the outside surface 14 for the purpose of causing a set (at least one) of internal slips 24 at least partially disposed within the recess 18 to be urged radially outwardly upon moving toward a largest diameter portion 26 of the frustoconical surface 20. The bearing surface is to be configured to support a resilient member 28 therein to facilitate the movement of the slips 24 toward portion 26. The resilient member may be an elastomeric spring, metal spring, etc.
Slips 24 include a set of ratchet teeth 30. The teeth are directional to facilitate movement of complementary teeth in a direction along teeth 30 toward a larger diametrical portion of body 12. The teeth are thus configured with a face 32 substantially transverse to an axis of body 12 and a face 34 substantially angled relative thereto (see
Radially outwardly adjacent outside surface 14 are positioned a lower slip assembly 40, an upper slip 50 and a seal element 60. The lower slip assembly comprises a slip body 42, a ratchet thread 44 complementary to thread 30. The thread 44 is illustrated in
Referring to upper slip 50, it will be appreciated that the slip 50 is narrower at one end 52 than it is at its other end 54. The angular surface 56 that creates the difference in ends 50 and 52 is selected to follow outside surface 14 of body 12 in such a way that an anchor surface 58 of slip 50 is maintained substantially in parallel with a longitudinal axis of body 12. This ensures that surface 58 will engage an inside surface 80 of the target tubular 82 (see
Axial load on the seal element is maintained post actuation by the action of the ratchet threads 30 and 44 against one another. As was noted hereinabove, the threads move along one another in one direction but do not move in the opposite direction. Once the unit is actuated then, the axial compressive load is maintained on the seal element indefinitely.
While the seal element may be of any deformable material, in one embodiment the element is metallic such that the seal is a metal-to-metal seal, highly resistant to downhole environmental factors. This embodiment is illustrated in
In the illustrated embodiments, the seal element 60 comprises end housings 62 and 64 and an intermediary structure 66 constructed to cause deformation of the element 60 such that the intermediary structure 66 rotates around its own center from a position where a longitudinal extent of the structure 66 is at a relatively more axial orientation to a position where the longitudinal extent is at a relatively more transverse orientation with respect to the axis of the body 12. The rotational movement is effected by the positioning of joining structures 68 and 70 relative to each other. As one will immediately appreciate from
Optionally, and illustrated in
It is to be understood that while the term “upper” and “lower” have been used in describing components of the insert seal unit disclosed herein, these are simply names to provide distinguishment between the two. They are not intended to connote that one is necessarily vertically “higher” than the other. In fact, the unit may be employed “upside down” equally well.
While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.