Patent Publication Number: US-9422786-B2

Title: Hybrid-tieback seal assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 61/644,168 filed May 8, 2012, which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention relates generally to tieback assemblies and, more particularly, to hybrid-tieback seal assemblies and associated methods of tying a well back to the surface or subsea well head. 
     Current methods used to tie a well back to the surface or subsea well head from an existing downhole liner hanger employ running a tieback string into the well. These tieback strings typically have seals at their bottom end that stab into a tieback receptacle or polished bore receptacle of an existing downhole liner hanger. This typical approach may be problematic due to the small space out window (i.e., length of space available to stab into the tieback receptacle), which is typically dictated by the length of the tieback receptacle. This typical approach may also be problematic in applications where the existing liner hanger is one that is very thin and as a result has a very low collapse value. When attempting typical tieback methods with thin liner hanger systems, there is a risk of collapsing the tieback receptacle, liner top, and/or tieback string. These thin liner hanger systems typically include, but are not limited to, the following sizes: 7⅝×9⅝, 9⅝×11¾, 11¾×13⅝, and 13⅝×16. As a result, a new and improved method of tying a well back to the surface or subsea well head is desirable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some specific exemplary embodiments of the disclosure may be understood by referring, in part, to the following description and the accompanying drawings. 
         FIGS. 1A-1C  depict a liner hanger system and a Hybrid-Tieback Seal Assembly (HTSA) in accordance with an illustrative embodiment of the present disclosure. 
         FIG. 2  is a flowchart depicting a method of tying a well back to the surface or subsea well head using the HTSA of  FIG. 1 , in accordance with an illustrative embodiment of the present disclosure. 
         FIGS. 3A-11  depict a sequence of method steps associated with a hybrid-tieback seal assembly, in accordance with certain embodiments of the present disclosure. 
     
    
    
     While embodiments of this disclosure have been depicted and described and are defined by reference to exemplary embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure. 
     DETAILED DESCRIPTION 
     The present invention relates generally to tieback assemblies and, more particularly, to hybrid-tieback seal assemblies and associated methods of tying a well back to the surface or subsea well head. 
     The terms “couple” or “couples” as used herein are intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect mechanical or electrical connection via other devices and connections. Similarly, the term “fluidically coupled” as used herein is intended to mean that there is either a direct or an indirect fluid flow path between two components. The term “uphole” as used herein means along the drillstring or the hole from the distal end towards the surface, and “downhole” as used herein means along the drillstring or the hole from the surface towards the distal end. 
     The present disclosure is directed to a system where a tieback string is set and sealed in an existing downhole liner hanger system, or into the host casing above the downhole liner hanger system. Setting and sealing the tieback string in the host casing above the liner hanger system may allow for the tieback receptacle or liner top of the liner hanger system to be isolated so it remains pressure balanced and has no risk of collapse. This system may incorporate the slips, sealing technologies, and other disclosures found in U.S. Pat. Nos. 6,761,221 and 6,666,276, the entireties of which are hereby incorporated by reference. This system may also be used with any well head system. 
     Illustrative embodiments of the present invention are described in detail herein. In the interest of clarity, not all features of an actual implementation may be described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the specific implementation goals, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of the present disclosure. 
     To facilitate a better understanding of the present invention, the following examples of certain embodiments are given. In no way should the following examples be read to limit, or define, the scope of the invention. Embodiments of the present disclosure may be used with any well head system. Embodiments of the present disclosure may be applicable to horizontal, vertical, deviated, or otherwise nonlinear wellbores in any type of subterranean formation. Embodiments may be applicable to injection wells as well as production wells, including hydrocarbon wells. 
     In certain embodiments, the present disclosure provides a method to tie a well back to the surface or subsea well head using a Hybrid-Tieback Seal Assembly (HTSA). In one embodiment, the tieback string is allowed to fill with fluid while running into the hole. In another embodiment, the present disclosure provides a method where pressure is allowed to build from the surface in the tieback string to actuate downhole devices. In certain embodiments, a device may be used to create a pressure differential in the tieback string. In one illustrative embodiment, the use of an inverted float collar may allow for fluid to enter the tieback string while being run into the hole. Once the tieback string is pressurized, the valve in the collar may close so that pressure may be increased in the tieback string to set slips and seals. In other embodiments, a downhole ball seat in the tieback string may be used and a ball may be dropped from the surface when it is desirable to set the HTSA. In this embodiment, when the ball is dropped from the surface and lands on the ball seat, it may act as a pressure barrier providing a pressure differential. Although certain exemplary devices are disclosed as suitable for use in creating a pressure differential in the tieback string, as would be appreciated by those of ordinary skill in the art having the benefit of the present disclosure, any other suitable device (e.g., plugs) may be used to create a pressure differential in the tieback string without departing from the scope of the present disclosure. 
     In certain embodiments, the methods discussed herein may incorporate slips that are independently hydraulically set and locked. These slips may be used to lock the tieback string from any movement up or down that could damage the seal between the tieback string and the host casing. In certain embodiments, the slips may be one piece or multiple pieces. In other embodiments, the methods discussed herein may incorporate the use of a metal to metal packer seal which may be hydraulically set. 
     Referring now to the Figures,  FIGS. 1A-1C  depict a Hybrid-Tieback Seal Assembly (HTSA), denoted generally with reference numeral  100 , and a downhole liner hanger system, denoted generally with reference numeral  130 , in accordance with an illustrative embodiment of the present disclosure.  FIGS. 1A-1C  show the HTSA  100  as it extends from one distal end to another. 
     In this illustrative embodiment, the liner hanger system  130  may be run and set in a wellbore (not shown). The liner hanger system  130  may be disposed within a host casing  160 . The liner hanger system  130  may comprise, but is not limited to, a packer seal, a running adapter, a hanger body, a slip, a packer cone, a pusher sleeve, a lock ring, a liner top and/or a receptacle  140 . In certain implementations, the receptacle  140  may include, but is not limited to, a tieback receptacle (TBR) or polished bore receptacle (PBR). Although certain components of the liner hanger system  130  are discussed for illustrative purposes, it would be appreciated by those of ordinary skill in the art, having the benefit of the present disclosure, that one or more components may be removed, modified, or added without departing from the scope of the present disclosure. 
     In certain embodiments in accordance with the present disclosures, the HTSA  100  may be set in the liner hanger system  130 . In other embodiments, the HTSA  100  may be set in the hosting casing  160 , positioned above the liner hanger system  130 . In the illustrative embodiment shown in  FIGS. 1A-1C , the HTSA  100  is set in the host casing  160 , positioned above the liner hanger system  130 . The HTSA  100  may be coupled to a tieback string  101 . The HTSA  100  may comprise one or more anchoring bodies, which may be hydraulically or mechanically set. In certain embodiments in accordance with the present disclosure, the one or more anchoring bodies may include a hold up body  111  and a hold down body  112 , which may be hydraulically or mechanically set. The hold up and hold down bodies  111 ,  112  may include a pusher sleeve  113  having an anti-backlash system to prevent movement and one or more single direction or bi-directional slips  114 , which may be independently set. The hold up and hold down bodies  111 ,  112  also may include a locking device (not shown), such as a lock ring, snap ring, collet, wedge or segmented slip system, and a shear pin. The slips  114  may be one piece or multiple pieces. Although certain components of the anchoring bodies  111 ,  112  are discussed for illustrative purposes, it would be appreciated by those of ordinary skill in the art, having the benefit of the present disclosure, that one or more components may be removed or modified without departing from the scope of the present disclosure. The HTSA  100  may incorporate any suitable slip mechanisms including, but not limited to, slip mechanisms disclosed in U.S. Pat. No. 6,761,221, the entirety of which has been incorporated by reference into the present disclosure. 
     The HTSA  100  may also comprise one or more metal to metal packer seal assemblies  117  which may be hydraulically or mechanically set. The packer seal assembly  117  may include a packer seal  118 . The packer seal assembly may also include, but is not limited to, a packer body, a pusher sleeve, a lock ring, a shear pin, a locking assembly, and/or a lock body. Although certain components of the packer seal assembly  117  are discussed for illustrative purposes, it would be appreciated by those of ordinary skill in the art, having the benefit of the present disclosure, that one or more components may be removed, modified, or added without departing from the scope of the present disclosure. The HTSA  100  may incorporate sealing technology disclosed in U.S. Pat. No. 6,666,276, the entirety of which has been incorporated by reference into the present disclosure. 
     In certain embodiments, the HTSA  100  may also comprise a device for creating a pressure differential in the tieback string  101 . In the illustrative embodiment shown in  FIGS. 1A-1C , the HTSA  100  comprises an inverted float collar  150 . The inverted float collar  150  may further comprise a valve  155  and a mule shoe or wireline entry guide  157 . The inverted float collar  150  may allow fluid to enter the tieback string  101  while the HTSA  100  is being run into the hole. The valve  155  in the inverted float collar  150  may close when the tieback string  101  is pressured down from the surface so that pressure may be increased in the tieback string  101  to set the anchoring bodies  111 ,  112  and/or packer seal assembly  117 . 
     In certain embodiments in accordance with the present disclosure, the HTSA  100  may be run into the wellbore (not shown) and landed in the well head  170  and set above the receptacle  140  of the liner hanger system  130 , within the host casing  160 . In this manner, the HTSA  100  may protect the host casing  160  above the liner hanger system  130  and may provide zonal isolation up to the surface or subsea well head. The HTSA  100  also may protect the inner diameter of the tieback string  101  from pressure located between the tieback string  101  and the host casing  160 . 
     Operation of the HTSA  100  in accordance with the illustrative embodiment of  FIGS. 1A-1C  will now be discussed in conjunction with  FIG. 2 .  FIG. 2  is a flowchart depicting illustrative method steps associated with a method to tie a well back to the surface or subsea well head using the HTSA  100  of  FIG. 1 , in accordance with an illustrative embodiment of the present disclosure. Although a number of steps are depicted in  FIG. 2 , as would be appreciated by those of ordinary skill in the art, having the benefit of the present disclosure, one or more of the recited steps may be eliminated, modified, or added without departing from the scope of the present disclosure. 
     First, at step  202 , the HTSA  100  is run into a wellbore (not shown). At step  204 , the inverted float collar  150  allows fluid to enter the tieback string  101  while the HTSA  100  is being run into the wellbore (not shown). At step  206 , the casing hanger  180  is landed in the well head  170 . As a result of landing the casing hanger  180  in the well head  170 , the HTSA  100  is located within the host casing  160 , above the liner hanger system  130 . At step  208 , tieback string  101  is pressured down from the surface and the valve  155  in the inverted float collar  150  closes to increase the pressure in the tieback string  101  to set the slips  114  and packer seal assembly  117 . At step  210 , the anchoring bodies  111 ,  112  of the HTSA  100  may be set within the host casing  160 , thus anchoring the HTSA  100  within the host casing  160 . The slips  114  of the anchoring bodies  111 ,  112  may be used to isolate the HTSA  100  from movement. The locking device of the anchoring bodies  111 ,  112  may retain the mechanical load applied to the slips  114  of the anchoring bodies  111 ,  112 . At step  212 , the packer seal  118  may be mechanically or hydraulically set within the host casing  160 , above the liner hanger system  130 . In certain embodiments, the packer seal assembly  117  may be set last so the HTSA  100  may be fully anchored prior to setting. At step  214 , the HTSA  100  may be tested down the annulus between the host casing  160  and the tieback string  101 . At step  216 , casing hanger  180  may be fully set, locked, and tested. 
       FIGS. 3A-11  depict a sequence of method steps associated with tying a well back to the surface or subsea well head using the HTSA  100  of  FIG. 1 , in accordance with certain embodiments of the present disclosure. 
       FIGS. 3A-3C  illustrate how the liner hanger system  130  may be run into the host casing  160  below where the HTSA  100  is to be set. The host casing  160  may be run to desired depth and hung off in the well head  170 . The liner hanger system  130  may then be run and set in the host casing  160 . 
     Referring now to  FIGS. 4A-4C ,  FIGS. 4A-4C  illustrate how the HTSA  100  may be run into the hole and positioned somewhere above the liner hanger system  130  as it is being landed into the well head  170 . The HTSA  100  may comprise an inverted float collar  150 , one or more anchoring bodies  111 ,  112  comprising slips  114 , which are independently hydraulically set, and a metal to metal packer seal assembly  117 , which is hydraulically set. The inverted float collar  150  may allow fluid to enter the tieback string  101  while it is being run into the hole, but when pressuring down the tieback string  101  from the surface, the valve  155  in the inverted float collar  150  may close so pressure may be increased in the tieback string  101  to set the slips  114  and packer seal  118  of the packer seal assembly  117 . The tieback string  101  may be coupled to the HTSA  100  and run in hole. The casing hanger  180  may be coupled to a casing hanger running tool  182 . A drill pipe  184  may be coupled to the casing hanger running tool  182  and continue to be run in hole. Finally, the HTSA  100  may be positioned somewhere above the previously run liner hanger system  130 . 
     Referring now to  FIGS. 5A-5C ,  FIGS. 5A-5C  illustrate how the hold up body  111  of the HTSA  100  may be set. The casing hanger  180  can be landed into the well head  170 . Weight from the tieback string  101  may then be slacked off onto the well head  170 . In this method, the casing hanger seal  186  may not be set and the casing hanger lock ring  188  may not be locked. The tieback string  101  can then be pressurized to a set pressure, for example 1000 psi, to set the slip  114  of the hold up body  111 . This sequence may keep the HTSA  100  from moving downhole. 
     Referring now to  FIGS. 6A-6C ,  FIGS. 6A-6C  illustrate how the hold down body  112  may be set. The tieback string  101  may be pressurized to a set pressure, for example 2000 psi, to set the slip  114  of the hold down body  112 . This sequence may keep the tieback string  101  from moving up the hole. 
     Referring now to  FIGS. 7A-7C ,  FIGS. 7A-7C  illustrate how the packer seal assembly  117  and packer seal  118  between the HTSA  100  and the host casing  160  may be set. The tieback string  101  may be pressurized to a set pressure, for example 3000 psi. This pressurization may start the packer setting process. The pressure may then be slowly increased to a final pressure, for example 5000 psi, to complete the packer setting process. The packer seal  118  of the packer seal assembly  117  is now set within the host casing  160 , above the liner hanger system  130 . 
     Referring now to  FIG. 8 ,  FIG. 8  depicts the casing hanger running tool  182  and casing hanger  180  landed in the well head  170 . This is the same position before and after the HTSA  100  is set and sealed. The HTSA  100  seal may be tested at this time. The HTSA  100  may be tested down the annulus between the host casing  160  and the tieback string  101 . Although certain exemplary method steps are disclosed as suitable for testing the HTSA  100 , as would be appreciated by those of ordinary skill in the art having the benefit of the present disclosure, any other suitable methods may be used without departing from the scope of the present disclosure. 
     Referring now to  FIGS. 9-11 ,  FIGS. 9-11  depict how the tieback may be completed by sealing, locking, and testing the casing hanger  180  and casing hanger seal  186 . The casing hanger lock ring  188  may be set and the casing hanger seal  186  may be set and tested. A drilling bottom hole assembly (not shown) may then be run in the hole to drill out the inverted float collar  150 .  FIG. 9  depicts how the casing hanger running tool  182  may be unlocked from the casing hanger  180 .  FIG. 10  depicts how the casing hanger seal  186  for the casing hanger  180  is mechanically loaded, but has not been fully set by pressure assist.  FIG. 11  depicts how pressure may be applied to fully set the casing hanger seal  186  and lock the seal into the well head  170 . The casing hanger seal  186  may then be tested. Although certain exemplary method steps are disclosed as suitable for setting, locking, and testing the casing hanger  180 , as would be appreciated by those of ordinary skill in the art having the benefit of the present disclosure, any other suitable methods may be used without departing from the scope of the present disclosure. 
     As would be appreciated by those of ordinary skill in the art, with the benefit of this disclosure, in certain implementations, due to the configuration of the HTSA  100  and the liner hanger system  130 , the casing hanger  180  may be landed without any special considerations or allowances for the position of the HTSA  100  within the host casing  160  or the liner hanger system  130 . Specifically, the casing hanger  180  may be landed regardless of the position of the HTSA  100  within the host casing  160  or the liner hanger system  130 . The system further eliminates the need for slack off weight or slack off distance to set the HTSA  100  in part due to the ability to the set within the host casing  160  or the liner hanger system  130  and the utilization of a pressure differential created in the tieback string  101  to set the HTSA  100 . 
     Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present invention. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. The indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces.