Patent Publication Number: US-2022228461-A1

Title: Wet shoe system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 63/139,999, which was filed on Jan. 21, 2021 and is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Casing is typically run into a well to complete the well. The casing is cemented in place by pumping a cement slurry through the casing and back up into an annulus formed between the well and the casing. The cement then sets in the annulus and subsequent well treatment processes may commence. 
     The cementing process presents several challenges. One such challenge is displacing the cement through the casing, and then preventing the cement from flowing back or “U-tubing” into the casing from the annulus. Float tools are widely used to address this challenge. Additionally, float tools permit the casing string to be partially supported in the well by buoyancy, rather than fully supported by the pipe handling equipment of the drilling rig, as the casing string is run into the well. 
     Float tools generally include a float collar and a float shoe, both of which may include one-way valves to prevent u-tubing. The float collar is connected to the casing string above the float shoe, and the float shoe connected to the end of the casing string. Generally, one or more lengths of casing separate the float collar from the float shoe. A “shoe track” is defined between the float collar and the float shoe. Cement may reside in the shoe track even after the cement job is complete. This shoe track may thus represent unused or generally blocked sections of the well. Thus, advances have been made toward a “wet” shoe, which eliminates at least some of this shoe track. In a wet shoe system, the float collar is close-coupled to the float shoe, and the wiper plugs generally land directly on the float collar and latch therein, displacing most or all of the cement out of the casing string through the float shoe. 
     In wet shoe systems, after the system is fully run and pressured, only the valves in the float collar and float shoe prevent the backflow of cement. These valves, however, experience flow through of the cement as it is displaced into the annulus. Erosion of the valves may thus be a concern, as it may cause the valves to leak. If the valves leak, cement may move into the float shoe and render the float shoe inoperative. This may result in lost time and expense spent on remediation efforts, such as drilling through the float shoe. 
     SUMMARY 
     Embodiments of the disclosure provide a downhole assembly including a float tool configured to be connected to a casing string and including one or more one-way valves configured to permit fluid flow in a downhole direction and to prevent fluid flow in an uphole direction, and a first wiper plug configured to be deployed into a well via the casing string and engage the float tool. The first wiper plug comprises a valve element that is configured to prevent fluid flow through the first wiper plug at least in the uphole direction. 
     Embodiments of the disclosure also include a method for cementing a well including deploying a float tool having one or more one-way valves into a well as part of a casing string, pumping cement into the casing string in the well, deploying a first wiper plug through the casing string down to the float tool so as to displace at least some of the cement from the casing string into an annulus between the casing string and the well, preventing the cement from flowing in an uphole direction through the first wiper plug using a valve element positioned in the first wiper plug, and pumping fluid through the first wiper plug in a downhole direction after deploying the first wiper plug down to the float tool. 
     Embodiments of the disclosure further include a downhole assembly including a float shoe having two or more one-way valves, a float collar coupled to the float shoe and having one or more one-way valves, a first wiper plug that is configured to land on the float collar, the first wiper plug including a valve element configured to prevent fluid flow through the first wiper plug at least in an uphole direction, and a second wiper plug that is configured to land on the first wiper plug, the second wiper plug including a rupture disk configured to block fluid flow through the second wiper plug. Upon rupturing the rupture disk, the second wiper plug permits fluid flow therethrough at least in a downhole direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure may best be understood by referring to the following description and accompanying drawings that are used to illustrate some embodiments. In the drawings: 
         FIG. 1  illustrates a side, cross-sectional view of a wiper plug having a valve element in a closed position, according to an embodiment. 
         FIG. 2  illustrates another side, cross-sectional view of the wiper plug having the valve element in an open position, according to an embodiment. 
         FIG. 3  illustrates a side, cross-sectional view of another wiper plug, according to an embodiment. 
         FIGS. 4, 5, and 6  illustrate side, cross-sectional views of a downhole assembly, which includes the wiper plug of  FIG. 1 , in different configurations during deployment, according to an embodiment. 
         FIG. 7  illustrates a flowchart of a method for cementing a well, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure describes several embodiments for implementing different features, structures, or functions of the invention. Embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference characters (e.g., numerals) and/or letters in the various embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed in the Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the embodiments presented below may be combined in any combination of ways, e.g., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure. 
     Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be intepreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. In addition, unless otherwise provided herein, “or” statements are intended to be non-exclusive; for example, the statement “A or B” should be considered to mean “A, B, or both A and B.” 
       FIGS. 1 and 2  illustrate side, cross-sectional views of a wiper plug  100 , according to an embodiment. The wiper plug  100  may be configured to be deployed into a well as part of a downhole float tool assembly for cementing a casing string into the well, as will be described, by way of example, in greater detail below. The illustrative wiper plug  100  includes a main body  102  through which an axially-extending bore  104  is defined. Fins or wipers  105  may extend from the main body  102 , and may be configured to press (e.g., deflect) against a surrounding tubular, such as the interior of the casing string, in order to at least partially seal therewith and press cement downwards as the wiper plug  100  is forced to move in a downhole direction through the casing string. 
     A valve element  106  may be positioned in the bore  104 . The valve element  106  may be configured to permit fluid flow through the bore  104  in a first direction, generally downhole toward the distal end of the well. The valve element  106  may also be configured to prevent fluid flow through the bore  104  in a second direction that is opposite to the first direction, e.g., generally uphole toward the surface. In at least some embodiments, the valve element  106  may be secured within the bore  104  and may not be deployed separately from the main body  102 . 
     In an embodiment, the valve element  106  may be a flapper valve. Accordingly, the valve element  106  may include a flapper  108  and a base  110 . In at least some embodiments, the base  110  may be generally cylindrical and its outer surface may seal with the bore  104 , e.g., in an enlarged portion of the bore  104 , as shown. Further, the flapper  108  may be pivotally secured to the base  110 , e.g., via a hinge. In at least some embodiments, the flapper  108  may be biased toward the base  110 , e.g., using a torsion spring in the hinge. Thus, the flapper  108  may be biased toward a closed position, in which the flapper  108  extends across and blocks the bore  104 , e.g., by sealing with the base  110 .  FIG. 1  specifically shows the flapper  108  in the closed position. Fluid flow in the first direction may overcome any biasing forces applied to the flapper  108  and pivotally displace the flapper  108  away from the base  110 , thereby moving the flapper  108  to an open position. As such, fluid flow in the first direction may be permitted past the flapper  108  in the first direction while the flapper  108  is in the open position.  FIG. 2  specifically shows the flapper  108  in a fully-open position; however, it will be appreciated that any position in which the flapper  108  permits fluid flow may be considered an open position. 
     In the illustrated embodiment, the valve element  106  also includes a spacer  111  and an end ring  113 . The spacer  111  may be coupled to and extend from the base  110 , and the end ring  113  may be coupled to the spacer  111 . The end ring  113  may be positioned in engagement with a shoulder  115  of the main body  102 , so as to locate the valve element  106  on one axial side in the bore  104 . The combination of the spacer  111  and the end ring  113  may provide sufficient space for the flapper  108  to pivot, unobstructed by engagement with other structures. 
     The valve element  106  is not limited to a flapper valve, however. In various embodiments, the valve element  106  may be any other type of valve. For example, the valve element  106  may be a ball-drop or caged-ball valve. In other examples, the valve element  106  may be a plunger valve, poppet valve, dart valve, an actuatable gate valve, a sleeve-actuated valve, or any other type of valve. 
     A rupture disk  112  may also be positioned in the bore  104 . For example, the rupture disk  112  may be adjacent to and engaged on an axial side by the base  110 . An upper connector  114  may also be at least partially received into the bore  104  and secured therein, e.g., by a threaded engagement. The upper connector  114  may engage an opposite axial side of the rupture disk  112 , such that the rupture disk  112  is entrained within the bore  104  by the upper connector  114  and the base  110 . As such, the valve element  106  is also entrained in the bore  104  between the upper connector  114  and the shoulder  115 . The upper connector  114  may include an open, threaded end, which may be configured to connect to a superposed plug, as will be described by way of example below, or another structure. 
     The wiper plug  100  may also include a lower latching member  116 . The lower latching member  116  may be secured at least partially in the bore  104 , e.g., threaded therein. Further, the lower latching member  116  may extend axially from the main body  102  and may provide one or more latching features that are configured to be received into engagement with and then retained by a connector of a subjacent structure (e.g., another wiper plug  100  or a float collar), so as to prevent displacement of the wiper plug  100  from the subjacent structure. 
       FIG. 3  illustrates a cross-sectional view of another wiper plug  300 , according to an embodiment. Certain aspects of the wiper plug  300  may be the same in structure and function as the wiper plug  100 , and like elements are generally given like numbering herein and a duplicative description thereof may be omitted. The wiper plug  300  may include a valve element  302 . The valve element  302  may be or include a solid disk or plug, which may be sealed in place in the bore  104 . In a specific embodiment, the valve element  302  may be entrained between the upper connector  114  and a shoulder  304  of the main body  102 . The valve element  302  may be made at least partially from a dissolvable material, i.e., a material intended to disintegrate in the presence of a specific wellbore fluid for a predetermined amount of time. For example, the dissolvable material may be a magnesium alloy, a thermoplastic, a plastic-encased animal lard, or the like. 
     The valve element  302  may be provided, e.g., in lieu of the rupture disk  112 , but in other embodiments, a rupture disk  112  could be included along with the valve element  302 . Similarly, the valve element  302  may be provided in lieu of the valve element  106 , as the valve element  302  may perform the function of blocking fluid flow in at least the uphole direction, as it may, prior to dissolution, prevent fluid flow in both directions through the bore  104 . After the predetermined amount of time in the wellbore fluid, the valve element  302  may dissolve and then permit bidirectional fluid flow in the bore  104 ; however, the predetermined amount of time may be configured to elapse after the cement has at least partially set in the annulus, such that u-tubing is no longer a concern. 
       FIG. 4  illustrates a side, cross-sectional view of a downhole assembly  400 , according to an embodiment. In this view, the assembly  400  includes a float tool  402 , a first or “bottom” plug  404 , and a second or “top” plug  406 . In particular,  FIG. 4  shows the float tool  402 , bottom wiper plug  404 , and top wiper plug  406  after each has been separately deployed, such that the bottom wiper plug  404  has landed on the float tool  402 , and the top wiper plug  406  has landed on the bottom wiper plug  404 . Accordingly, the top wiper plug  406  is superposed with respect to the bottom wiper plug  404 , such that the second wiper plug  404  is positioned axially between the top wiper plug  406  and the float tool  402 . 
     In an embodiment, the bottom wiper plug  404  includes the valve element  106  (e.g., including the flapper  108 ), and thus may be an implementation of the wiper plug  100  discussed above. In other embodiments, the top wiper plug  406  may be the wiper plug  100 , or both may be implementations of the wiper plug  100 , such that either or both have valve elements  106 . Further, in some embodiments, either or both of the bottom and top wiper plugs  404 ,  406  may include the valve element  302  and may thus be implementations of the wiper plug  300 . In still other embodiments, a single plug or three or more plugs, any one or more of which may include the valve element  106  and/or the valve element  302 , may be utilized. 
     Further, the wiper plugs  404 ,  406  may each include a rupture disk  112 - 1 ,  112 - 2  (e.g., implementations of the rupture disk  112 ). The rupture disks  112 - 1 ,  112 - 2  may be configured to permit the wiper plugs  404 ,  406  to be pumped down through the casing string as a solid body, thereby pressing any cement downward through the casing string. Although both rupture disks  112 - 1 ,  112 - 2  are illustrated as intact, in some embodiments, the rupture disk  112 - 1  of the bottom wiper plug  404  may rupture prior to deployment of the top wiper plug  406 , so as to permit fluid communication through the bottom wiper plug  404  and thereby permit the top wiper plug  406  to move downhole and land on the bottom wiper plug  404 . 
     In the illustrated embodiment, the float tool  402  includes a float collar  410  and a float shoe  412 . The float collar  410  may be received in or connected to a casing string, which extends past the wiper plugs  404 ,  406  to the surface (i.e., the wiper plugs  404 ,  406  are deployed through the casing string and pumped down into their illustrated positions). The float collar  410  generally includes a one-way valve  414 , e.g., a plunger valve, as shown. The one-way valve  414  may permit fluid flow in the downhole direction through the float collar  410 , but prevent fluid flow in the uphole direction, when functioning properly (e.g., not leaking). 
     The float shoe  412  may be connected to the float collar  410  and may form the distal end of the casing string. The float shoe  412  may include one or more one-way valves (two shown:  420 ,  422 ), which may be, for example, plunger valves. The one-way valves  420 ,  422  may be configured to permit downhole fluid flow and prevent uphole fluid flow through the float shoe  412 , when functioning properly (e.g., not leaking). 
     Because cement slurry may be abrasive or otherwise tend to erode the material making up the valves  414 ,  420 ,  422 , wear on the one-way valves  414 ,  420 ,  422  may be present. In some cases, this wear can permit cement slurry, prior to setting, to leak back from the annulus into the float shoe  412 , the float collar  410 , and/or the casing string. To avoid this, one or more of the wiper plugs  404 ,  406  is provided with the valve element  106 , as noted above. Since these wiper plugs  404 ,  406  may follow the cement, the cement may generally not flow through the valve element  106  provided therein, and thus the valve element  106  may not experience the same abrasive interaction with the cement slurry or be prone to the same type of erosion as the valves  414 ,  420 ,  422 . Accordingly, the valve element  106  may be more likely to remain fully sealed and intact and thereby prevent leakage of cement back into the casing. 
     The wiper plug  300  including the dissolvable valve element  302  may operate similarly, and may be readily used in the assembly  400 . For example, prior to dissolving, the solid plug of the valve element  302  serves as a barrier to backwards flow of the cement. The predetermined amount of time that the dissolvable valve element  302  takes to dissolve may be selected so that it is sufficient for the cement to at least partially set, thereby ending the potential for u-tubing, as the cement is less flowable. As such, the dissolvable valve element  302  does not erode from flow of cement therepast, but rather assists in displacing the cement out of the float shoe  412  until the valve element  302  dissolves, upon which it permits fluid flow (e.g., in a downhole direction) therethrough. 
     Returning to the illustrated examples,  FIG. 5  shows the assembly  400  with both of the rupture disks  112 - 1 ,  112 - 2  from  FIG. 4  having been ruptured and removed. For example, the rupture disk  112 - 1  may be ruptured after deploying the bottom wiper plug  404  down to the float collar  410 , and before deploying the top wiper plug  406 . Then the rupture disk  112 - 2  of the top wiper plug  406  is ruptured after deploying the top wiper plug  406  down into engagement with the bottom wiper plug  404 . The flapper  108 , however, is in a closed position, which blocks fluid flow in the uphole direction (to the left), at least.  FIG. 6  shows the flapper  108  in the open position, after the rupture disks  112 - 1 ,  112 - 2  are ruptured, permitting downhole (to the right) directed fluid communication, e.g., to permit pump-down of wireline tools. 
       FIG. 7  illustrates a flowchart of a method  700  for cementing a wellbore, according to an embodiment. The method  700  may be executed by operation of an embodiment of the downhole assembly  400  and one or more of the wiper plugs  100 ,  300  discussed above, and thus will be described in herein by reference thereto. However, it will be appreciated that some embodiments of the method  700  may be executed using different structures. Further, the ordering of the various aspects of the method  700  provided herein is merely an example, as the steps of the method  700  may be performed in a different sequence, combined, separated, and/or performed in parallel. 
     In the illustrated embodiment, the method  700  may include deploying a float tool  402  on a casing string to a desired location in the well, as at  702 . The method  700  may then include pumping cement slurry into the casing string, as at  704 . Next, a bottom wiper plug  404  may be deployed into the casing, as at  706 , and pumped down to the float tool  402 , thereby displacing the cement slurry from the casing string, through the float tool  402 , and into the annulus between the casing string and the wellbore. 
     In some embodiments, a rupture disk  112 - 1  of the bottom wiper plug  404  may be ruptured by increasing a pressure in the casing string to a predetermined level, as at  708 . The predetermined pressure may be between about 1000 psi and 1500 psi, e.g., about 1250 psi. This may permit fluid communication in at least a downhole direction through the bottom wiper plug  404 . In some embodiments, the method  700  may include preventing reverse fluid flow in an uphole direction through the bottom wiper plug  404  using a valve element  106  provided in the bottom wiper plug  404 , as at  710 . 
     The method  700  may then include pumping (or otherwise deploying) one or more top wiper plugs  406  through the casing string into engagement with the bottom wiper plug  404 , as at  712  such that a fluid communication path is established directly between the top wiper plug  406  and the bore  104  of the bottom wiper plug  404 . In some embodiments, the method  700  may include dissolving a dissolvable valve element  302  of the top wiper plug  406 , e.g., after pumping down the one or more top wiper plugs  406 , as at  714 . 
     In some embodiments, the top wiper plug  406  (or at least one of the top wiper plugs  406 ) may include a rupture disk  112 - 2 . At  716 , the method  700  may thus include rupturing the rupture disk  112 - 2  of the top wiper plug  406  by increasing the pressure in the casing string to a predetermined level (e.g., about 1000 psi to about 1500 psi, e.g., about 1250 psi), and thereby establish fluid communication through the top wiper plug  406 , bottom wiper plug  404 , and float tool  402 . The method  700  may then include pumping fluid through the top wiper plug  406 , bottom wiper plug  404 , and float tool  402 , e.g., to support deployment of wireline tools into the casing string, as at  718 . 
     The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.