CA3145373A1 - Modified float collar and methods of use - Google Patents

Abstract

An improved float collar assembly and methods of use for completing a subterranean wellbore are provided, the assembly comprising an inner collar releasably positioned within an outer housing, the collar having at least one valve for controlling fluid flow through the assembly, and the collar initially serving to cover at least one fluid flow port in the housing in a first 'closed' position and then, when released, shifting to uncover the at least one fluid flow port in a second 'open' position. The presently improved assembly may provide a dual-functioning tool operative as a float collar during casing/cementing operations, and a toe port sleeve during wellbore treatment operations.

Description

MODIFIED FLOAT COLLAR AND METHODS OF USE
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims benefit of priority to U.S.
Provisional Patent Application No. 63/141,054 entitled "MODIFIED FLOAT COLLAR AND METHOD OF
USE" and filed January 25, 2021, which is specifically incorporated by reference herein for all that is discloses or teaches.
FIELD

[0002] Embodiments herein generally relate to apparatus for use in the oil and gas industry, and more particularly to an improved float collar assembly for use during cementing operations that is also operative as a toe sleeve during treatment operations, such as fracing.
BACKGROUND

[0003] Various tools and methods are required for the completion of subterranean wellbores penetrating a formation for the purpose of recovering hydrocarbons. Wellbores are drilled into the subterranean formation using any suitable drilling technique, and extend substantially vertically away from the earth's surface over a vertical wellbore portion, partially vertically over one or more deviated wellbore portions, and/or substantially horizontally over a horizontal wellbore portion. At least some of the wellbore is lined with tubular casing during casing operations.
The casing is secured into position against the formation using cement during cementing operations. At least a portion of the wellbore is also punctured in order to provide treatment fluids and other materials access to the formation during treatment operations (e.g., fracing operations).

Date Recue/Date Received 2022-01-11

[0004] Float equipment is commonly used during cementing operations.
Typically positioned in the lower sections of casing, float equipment can help reduce strain on the rig's hoisting system during placement of the casing in the wellbore, and to guide the casing past ledges and sidewall cavings as the casing passes through deviated sections of the wellbore. Float equipment can also be used to provide a backpressure valve within the casing bore, preventing the re-entry or "u-tubing" of cement slurry into the casing, and also to provide a landing point for cementing plugs pumped in front of and/or behind the slurry.

[0005] Float equipment often includes one or more of a guide shoe, a float shoe (with or without a valve), or a float shoe and a float collar (with or without a valve, e.g., a "landing collar"). Float collars are typically positioned a few joints above the shoe in the casing string, prior to running the casing into the wellbore, and comprise a tubular housing forming a central fluid passageway with one or more valves to control fluid flow therethrough. Float collars can be also configured to receive and latch plugs, such as cement and/or wiper plugs, used during the cementing operations.

[0006] Once the casing has been cemented in place, plugs or other downhole componentry obstructing the wellbore need to be removed. In some cases, specific tools can be used to selectively puncture or open the wellbore to reinstate fluid flow through the casing string. For example, perforating devices are commonly deployed downhole on wireline, slickline, cable, or on tubing string, often with sealing devices such as bridge plugs, packers, and straddle packers, in order to isolate portions of the wellbore for fluid treatment. In some wellbores, ported tubulars may be run in hole as collars, subs, or sleeves, on tubing string or production liner string. The ported tubulars Date Recue/Date Received 2022-01-11 are typically spaced at intervals generally corresponding to desired treatment locations, and ports can be selectively opened using any number of methods to form fluid delivery conduits to the formation.

[0007] Known mechanisms for providing fluid access to the formation are not always reliable, however, particularly during multi-stage fracing operations in horizontal wellbores, or in circumstances where achieving a feed rate can be difficult.
For example, in some formations, fracing operations may struggle to increase hydrocarbon production rates, particularly where the formation has low permeability (e.g. shale formations). Circumstances may also arise during well completion operations where it is necessary to provide fluid access to the formation (i.e. out of the toe of the wellbore), such as to pump bottom hole assemblies into the toe of the wellbore, particularly during extended reach scenarios, or to set the bottom hole assembly within the wellbore using coiled tubing.

[0008] There remains a need for an improved apparatus that can dependably access, open, or create fluid treatment ports downhole. In some embodiments, it may be advantageous that such an improved apparatus be incorporated within float equipment positioned at or near the toe of the wellbore. As would be appreciated, such an apparatus could, inter alia, serve to reduce the number downhole wellbore completion tools required, as well as the connections therebetween, ultimately reducing the length of the bottom hole assembly.
SUMMARY

[0009] According to embodiments, an improved float collar assembly and methods are use are providing, the assembly comprising an outer tubular housing Date Recue/Date Received 2022-01-11 having a substantially cylindrical sidewall with an outer surface, an inner surface, and defining a central housing bore, the sidewall forming at least one fluid port extending therethrough, an inner tubular collar sealably positioned within the central housing bore, the inner collar having at least one valve for controlling fluid flow therethrough, one or more mechanical connectors releasably connecting the inner collar to the outer housing, wherein, when connected, the inner collar is retained in a first closed position preventing fluid flow through the at least one fluid ports, and wherein, when disconnected, the inner collar is shifted within central housing bore to a second open position permitting fluid flow through the at least one fluid ports.

[0010] In some embodiments, the assembly may further comprise at least one valve comprises a check valve.

[0011] In some embodiments, the inner collar of the assembly may be configured to receive at least one cement plug, wherein the plug may be solid, or may comprise one or more dissolvable or burst portions.

[0012] In some embodiments, the assembly may be operably connected to a casing string and may be positioned at or near a toe end of a subterranean wellbore.

[0013] According to embodiments, methods of using an improved float assembly for completing a subterranean wellbore with a casing string lowered into the wellbore are provided, the method comprising providing a float collar assembly operably connected to the casing string, the float collar assembly having an outer tubular housing mechanically connected to an inner tubular collar, the inner collar sealably retained in a first closed position within the housing thereby covering at least one fluid flow port in the housing to preventing fluid flow therethrough, and having at Date Recue/Date Received 2022-01-11 least one valve for preventing fluid flow through the assembly, running the casing string into the wellbore with the assembly in the first closed position, and disconnecting the inner collar from the outer housing, shifting the inner collar to a second open position uncovering the at least one fluid flow ports in the housing to permit fluid flow therethrough.

[0014] In some embodiments, prior to disconnecting the inner collar from the outer housing, the method comprises introducing cementing fluids into the casing string to cement the casing to the subterranean wellbore. The cementing fluids may be introduced at fluid pressures sufficient to open the at least one valve in the inner collar without disconnecting the inner collar from the outer housing.

[0015] In some embodiments, the method further comprises introducing at least one cement plug into the casing string to land in the inner collar and increasing fluid pressures above the at least one cement plug to hydraulically disconnect the inner collar from the outer housing.

[0016] In some embodiments, the method further comprises mechanically disconnecting the inner collar from the outer housing permitting fluid to flow through the at least one fluid ports and introducing treatment fluids into the casing string and out of the assembly through the at least one fluid ports.

[0017] In some embodiments, the method further comprises that the at least .. one cement plug contains a dissolvable or burstable portion, and treatment fluids are passed through the at least one cement plug.

[0018] According to embodiments, the methods may comprise running the assembly in the first closed position during casing and cementing operations, and then Date Recue/Date Received 2022-01-11 triggering the inner collar to shift to the second open position to permit fluid flow through the at least one fluid flow ports during wellbore treatment operations.
BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a cross-sectional side view of the present apparatus, according to embodiments;

[0020] Figure 2 is a cross-sectional side view of the apparatus shown in FIG.
1, the apparatus shown in a closed position (i.e., treatment fluid ports are closed);

[0021] Figure 3 is a cross-sectional side view of the apparatus shown in FIG.
1, the apparatus shown in an open position (i.e., treatment fluid ports are open);

[0022] Figures 4A is a cross-sectional side view of an alternative embodiment of the apparatus shown in FIG. 1, the embodiment comprising at least one selectively opened port (e.g., a dissolvable port or a burst port/disk);

[0023] Figure 4B is a cross-sectional side view of a further alternative embodiment of the apparatus shown in FIG. 1, the embodiment comprising a ported housing having at least one dissolvable fluid port;

[0024] Figure 5 is a cross-sectional side view of an alternative embodiment of the present apparatus, the embodiment comprising at least two cement plugs;
and

[0025] Figure 6 is a cross-sectional side view of an alternative embodiment of the present apparatus shown in FIG. 1, the embodiment comprising a J-gap;

[0026] Figure 7 is a cross-sectional side view of an alternative embodiment of the present apparatus shown in FIG. 6, the embodiment comprising a float collar without a valve, i.e. a landing collar, and a debris trap; and Date Recue/Date Received 2022-01-11

[0027] Figure 8 is a cross-sectional side view of yet a further alternative embodiment, the embodiment comprising a cement plug having at least one dissolvable portion.
DETAILED DESCRIPTION OF EMBODIMENTS

[0028] According to embodiments, an improved float collar assembly and methods of use are provided, the assembly advantageously operable as both a float collar used for running in and cementing casing string in a subterranean wellbore, and as a toe sleeve that can be selectively opened to establish fluid flow into the formation during downhole operations, such as fracing. In some embodiments, the presently improved float collar assembly may comprise an inner collar releasably positioned within an outer housing, the collar initially serving to cover at least one fluid flow port in the housing in a first 'closed' position and then, when triggered to shift within housing, the collar serving to uncover the at least one fluid flow port in the housing in a second 'open' position. As will be described in more detail, in this manner, the present assembly may be configured to run in-hole in the closed position to assist in 'floating' the casing downhole and then once in position, as desired, to be selectively opened to provide fluid access through the fluid flow ports to the formation.

[0029] According to embodiments, the presently improved float collar assembly may also be configured to provide at least one valve positioned within a central bore of the assembly, the valve operable to prevent fluids from flowing through the assembly, further serving to seal off and isolate a portion of the casing string as it 'floats' downhole. Once landed at or near the toe of the wellbore, and with the inner collar retained in the 'closed' position within housing, cementing fluids/slurry can be Date Recue/Date Received 2022-01-11 pumped downhole to controllably open the at least one valve within the assembly, enabling the slurry to pass through the bore of the assembly and out the bottom of the casing string into the annular space. As will be described in more detail, in this manner, the present assembly may be configured to run in-hole in the closed position to assist in 'floating' the casing downhole and then, during cementing operations, for the central bore of the assembly to be controllably opened to provide cementing fluids/slurry access through the central bore of the assembly and out the bottom of the casing string.

[0030] According to embodiments, the presently improved float collar assembly may also be configured to land and securely receive at least one cement plug and, with the inner collar still retained in the 'closed' position within housing, blocking the at least one valve and preventing the opening of the central bore of the assembly.
Then, at any desired time (e.g., once cement has sufficiently cured), pressurized fluids can be pumped downhole to trigger the inner collar to shift from its 'closed' position within the housing, opening the at least one fluid ports in the assembly housing. More specifically, fluids can be pumped downhole until pressures imposed upon the at least one cement plug landed in the assembly are sufficient to shear the connection between the inner collar and the housing, causing the inner collar to move within the housing and expose the fluid ports. In this manner, as above, the present assembly may serve as a toe sleeve to readily establish fluid flow from the assembly into the formation for downhole operations, such as fracing operations.

[0031] According to embodiments, the presently improved float collar assembly may also be configured to provide fluid flow out the bottom of the casing string during Date Recue/Date Received 2022-01-11 treatment operations. For example, if desired, the at least one cement plug landed within the assembly may be configured to be controllably opened (e.g., via a burst disk or dissolvable material), thereby serving to re-establish fluid circulation through the assembly and out the bottom of the casing string into the wellbore.

[0032] Broadly, in use, the presently improved float collar assembly may be operably connected to a casing string and run in hole in a first 'closed' position and sealed configuration, where fluid is prevented from flowing through the central bore of the assembly and from flowing through the at least one port through a sidewall of the assembly. In this manner, the assembly can seal off and isolate a portion of the casing to 'float' the string downhole during casing operations. Then, when desired, the central valve may be controllably opened to permit cementing fluids/slurry pumped downhole to pass through the assembly and out the bottom of the casing string into the annular space. The valve prevents fluids from 'u-tubing' into the casing string.

[0033] Once cementing is completed, the presently improved float collar assembly may be triggered to shift to a second 'open' position, uncovering at least one fluid flow port in the sidewall of the assembly and allowing fluid flow from the assembly into the formation. In this manner, by controllably shifting the inner collar from its position within the outer housing, access to the formation can be readily established, e.g., for fracing operations. The presently improved float collar assembly and methods of use will now be described in more detail.

[0034] In the present description of embodiments, the terms "above/below" and "upper/lower" are used for ease of understanding and are generally intended to mean the relative uphole and downhole direction from surface.

Date Recue/Date Received 2022-01-11

[0035] More specifically, in some embodiments, the presently improved float collar assembly may be operably connected to, and run in hole with, a casing string.
The improved assembly may comprise an inner tubular collar releasably positioned within an outer tubular housing and at least one valve positioned the central bore of the assembly. As the assembly is floated downhole, the inner collar within the housing may be in a first 'closed' position, which blocks fluid from flowing through the at least one fluid ports in the housing, and the valve may be in a 'sealed' configuration, which blocks fluid from flowing through the assembly. When the casing has landed at or near the toe of the wellbore, or any other desired position within the wellbore, and cementing operations are commenced, fluids may be pumped through the central bore of the assembly at a fluid pressure sufficient to open the at least one valve within the central bore (i.e., causing check valve to unseat), but insufficient to shift the inner collar away from the fluid ports (i.e. maintaining the inner collar at the first 'closed' position). In this manner, cementing fluids may be pumped downhole and through the assembly landed at or near the toe of the wellbore (via the at least one valve in the central bore of the assembly) and out the bottom of the casing string without exposing the fluid flow ports to the formation. As cementing operations are completed and the wellbore is prepared for subsequent downhole operations, at least one plug may be introduced into the wellbore to land in the assembly, blocking the at least one valve and again preventing fluid flow through the casing string (i.e., causing check valve to reseat). Fluid pressures above the plugged assembly can then be increased until the inner collar is sheard from the outer housing to a second 'opened' position, opening the at least one fluid ports and establishing connection to the formation.
Date Recue/Date Received 2022-01-11

[0036] In some embodiments, the presently improved float collar assembly may be configured to run in hole with standard casing string such that the assembly lands at or near the distal or toe end of the wellbore. In some embodiments, the present assembly may be positioned one or two casing string joints above or uphole from a float shoe (not shown) and may provide at least one valve serving as a back-up check valve for the float shoe (or as a primary check valve for a guide shoe). As such, the present assembly can serve to reduce surge pressure against the wellbore wall and permit the casing to be more readily lowered to total depth.

[0037] Once at depth and when desired, one or more cement plugs may be lowered downhole to in the assembly, the plugs operative to obstruct the flow of fluids through the assembly. As known in conventional cementing procedures, fluid pressures within the casing may be sufficient to land or "bump" the cement plug(s) within the assembly, but below preset pressures required to activate mechanical connectors (e.g., shear pins) retaining the inner collar in the closed position within the housing (as will be described below).

[0038] Then, when conventional downhole operations are desired, the presently improved float collar assembly may provide easy access to a plurality of fluid treatment ports extending through the outer housing of the assembly, such ports being selectively opened to form a fluid delivery conduit to the formation (i.e., through the casing into the formation). In some embodiments, the present assembly may comprise an inner collar that is initially biased to cover over the treatment ports in a 'closed' position (e.g., during the cementing application), and then is shifted downwardly away from the ports to an 'open' position allowing treatment fluids to reach the formation. In Date Recue/Date Received 2022-01-11 this manner, where desired, treatment fluids applied to the wellbore can exit the assembly through the treatment ports to reach the surrounding formation.

[0039] The present apparatus and methods of use will now be described in more detail having regard to FIGS 1 ¨ 8.

[0040] Having regard to FIG. 1, a first embodiment of the presently improved float collar assembly 10 is provided. The present float collar assembly 10 may be configured for installation within the lower end of a tubular casing 11 having central bore 12. Float collar assembly 10 may comprise upper/uphole end 13 and lower/downhole end 15, each upper and lower end 13,15 being configured for operable connection with casing 11. For example, upper and lower ends 13,15 of the present float collar assembly 10 may comprise threaded connections, or any other suitable connection known in the industry.

[0041] In some embodiments, the present float collar assembly 10 may comprise a ported tubular outer housing 20 and an inner tubular collar 30 that may be slidably positioned within outer housing 20. In some embodiments, collar 30 may comprise at least one valve 34 for controlling fluid flow through the assembly 10, and housing 20 may form a plurality of fluid ports 24 for selectively opening multiple fluid flow passageways through the sidewall of the assembly 10 into the formation.

[0042] As will be described in more detail, in a first 'run-in' or closed position, inner collar 30 may be temporarily restrained from displacement within housing (e.g., by one or more mechanical connectors, or shear pins), such run-in position allowing the passage of fluids through the central bore of assembly 10 during the Date Recue/Date Received 2022-01-11 cementing process while preventing fluids from passing through the treatment fluid ports 24 into the formation.

[0043] As will be described in more detail, in a second 'treatment initiation' or open position, inner collar 30 may be displaced downwardly within housing 20 (e.g., shear pins are sheared) opening the fluid ports 24, such 'treatment initiation' position preventing the passage of fluids through the central bore of assembly 10 while providing a less tortuous flow path for treatment fluids passing from the assembly into the formation through the plurality of fluid ports 24.

[0044] Advantageously, embodiments of the presently improved float collar .. assembly 10 provides dual-functionality in a single apparatus that can be used during both casing/cementing operations and treatment operations (e.g., fracing), and/or any other suitable operations performed during the recovery of hydrocarbons from a subterranean formation.

[0045] More specifically, having regard to FIG. 2, the present assembly may comprise an outer housing 20, the housing 20 consisting of a tubular having a substantially cylindrical sidewall with an outer surface 21 and an inner surface 23 defining a central bore 22. In some embodiments, the internal diameter of central bore 22 may be about equal to the internal diameter of casing bore 12, thus forming a substantially unrestricted and continuous fluid flow path through casing 11 and downhole to float/guide shoe therebelow (not shown). For example, the internal diameter of central bore 22 may be approximately equal to standard production casing, liner, or the like, as desired.

Date Recue/Date Received 2022-01-11

[0046] In some embodiments, outer housing 20 may further comprise at least one apertures or fluid port(s) 24 extending through the sidewall of housing 20, such fluid ports 24 positioned to be radially spaced about the circumference of sidewall for providing fluid passageways from the central bore 22 of assembly 10 into the .. formation (not shown). Fluid ports 24 are formed in outer housing 20 but not in collar 30 such that, when collar 30 is securely positioned within housing 20 in a first 'closed' position, ports 24 are covered by collar 30 (as shown in FIG. 2). In some embodiments, as will be described, further treatment fluid ports, such as dissolvable ports, may also be provided and opened through outer housing 20 as desired (e.g., 46; FIG.
4B).

[0047] As above, inner collar 30 may be held in the closed position using one or more mechanical connectors including, without limitation, shear pins, fasteners, by interlocking or mating with a profile on the inner surface of housing 20 (e.g., J-gap), or by any other suitable means known in the industry.

[0048] In some embodiments, outer housing 20 may comprise one or more means for controllably shifting inner collar 30 within bore 22 of housing 20, i.e., for displacing inner collar 30 axially downhole within housing 20. Still with reference to FIG. 2, in some embodiments, outer housing 20 may comprise one or more apertures or pin holes 26 for receiving and retaining at least one shear pin 27. Inner collar 30 may comprise one or more corresponding shear pin grooves for receiving pins 27, such that, when pins 27 are in place within pin holes 26, uphole or downhole displacement of the collar 30 within bore 22 is prevented (i.e., axially within central bore 22 relative to the longitudinal axis of the wellbore). Although shear pins/holes are described as a means for restraining axial displacement of collar 30 within housing Date Recue/Date Received 2022-01-11 20, such description is for illustration purposes only. It should be understood that any suitable means known in the industry for controllably restraining movement of collar 30 relative to housing 20 are contemplated such as, without limitation, collets, shear rings, or canted coil springs.

[0049] Having further regard to FIG. 2, one or more annular or 0-ring seals may be used to form a fluid-tight sliding connection between housing 20 and collar 30, where at least one of the one or more seal may be positioned uphole of fluid ports 24 and at least another one of the one or more seals may be positioned downhole of said ports 24. For example, upper and lower annular seals 29 (e.g., 0-rings) may be provided about outer sidewall 31 of collar 30 for sealingly engaging inner sidewall 23 of housing 20 and preventing fluid from passing therebetween.

[0050] Optionally, in some embodiments, housing 20 may also form one or more apertures 28 for displacing fluids trapped in the casing bore 12 between assembly 10 and the cemented toe of the wellbore downhole thereof (e.g., at the shoe). In this manner, apertures 28 may serve as fluid relief port(s) for venting excess fluids from the casing bore 12 into the annular space. For example, where the bottom of the wellbore (i.e., the shoe) is sealed off or cemented completely, any volume of fluid within casing bore 12 below the assembly 10 may exit the casing string through the at least one relief apertures 28.

[0051] As above, the present assembly 10 may comprise an inner collar 30 sealably positioned within the central bore 22 of housing 20, the collar 30 consisting of a tubular having a substantially cylindrical sidewall with an outer surface 31 and an inner surface 33 defining a central bore 32. The outer diameter of collar 30 may be Date Recue/Date Received 2022-01-11 about equal to or less than the internal diameter of casing and housing bores 12,22, respectively, thus providing a frictional fit between collar 30 when slidingly received within housing 20.

[0052] Central bore 32 of collar 30 may provide a continuous fluid flow path through assembly 10. For example, as will be described, fluids pumped through casing bore 12 enter housing bore 22 and flow through central bore 32 of collar to open valve 34, thereby allowing fluid to flow continuously through assembly 10 to the bottom of the casing string 11 therebelow. In this manner, the internal diameter of central bore 32 of collar 30 may be sized so as to allow cementing fluids/flurry to pass through bore 32 and open valve 34.

[0053] According to embodiments, having regard to FIGS. 2 and 3, collar 30 may comprise at least one valve 34, such as a check valve. Valve 34 may allow the passage of fluids flowing downhole through the assembly 10 but may prevent the inflow of fluids flowing uphole into the casing 11 from the wellbore (i.e., u-tubing). In some embodiments, valve 34 may be a flapper or spring loaded valve wherein the valve 34 is biased to a closed position (i.e., valve in seated), and then selectively opened in response to pressurized fluid flow from surface (in the downward direction) through the casing 11 (i.e., valve is unseated). In this manner, when in a closed position, valve 34 serves to seal off the central bore 12 of casing 11, isolating a portion thereof and assisting in 'floating' the casing downhole. Then, when desired, pressurized fluids/slurry can be pumped downhole to open valve 34, allowing the fluids to through the assembly 10 the bottom of the casing 11.

Date Recue/Date Received 2022-01-11

[0054] Having regard to FIG.3, valve 34 may comprise any suitable form of 'one-way' fluid flow valve including, without limitation, a check valve. For example, in some embodiments, collar 30 may be configured to form a valve seat 35 for sealably receiving a poppet 36 to close the central bore 32 of collar 30 (and effectively sealing off the central bore 12 of casing 11). Poppet 36 may form a head portion 37 and a stem portion 38. At least one spring 39 may be mounted on stem 38, the spring serving to bias poppet 36 against valve seat 35 for sealing of valve 34. In this manner, valve 34 may remain in a closed, seated position until fluid pumped through the casing string bore 12 reaches a sufficient pressure to overcome the bias of the spring 39.
Once sufficient pressure is reached, poppet 36 will release from seat 35 and valve 34 will open.

[0055] As above, during cementing operations, cementing fluids/slurry is pumped downhole through central casing bore 12 and out the bottom of casing 11 where it travels up around the outside of casing 11 to fill the annular space, cementing the casing in place within the wellbore. In order to flow through the at least one valve 34, fluid pressures of the slurry must be sufficient to overcome the resistance of the spring 39 and to unseat valve head 37 of poppet 36 from valve seat 35, displacing the poppet 36 downwardly and unseating valve 34. When the pumping of cementing fluids/slurry ceases and fluid pressures above the valve 34 are reduced, spring 39 will bias upwardly, returning poppet 36 into valve seat 35 and reseating valve 34.
When closed, valve 34 not only obstruct fluids flowing downhole through casing bore 12 but also prevents cementing fluids/slurry from inadvertently u-tubing back into casing 11 from the wellbore. In some embodiments, valve 34 may be configured such that fluid Date Recue/Date Received 2022-01-11 pressures sufficient to open the valve 34 may be less than fluid pressures sufficient to shift collar 30 downhole (i.e., to cause a change in pressure across the flow restriction caused by the internal diameter of collar 30).

[0056] As during conventional cementing operations, when desired, one or more cement plugs may be pumped downhole to wipe excess cement from the casing 11. Displacement fluids can then be pumped into the casing 11, forcing the plug(s)s downward to compress or push residual cement within bores 12,22,32 through the bottom end of the casing 11.

[0057] Having regard to FIG. 3, in some embodiments, upper end of inner collar 30 may be configured for receiving at least one cement plug 40. Plug(s) 40 may comprise a cylindrical body forming an axial passage 42 extending therethrough, and may comprise at least one wiper vane(s) or fin(s) 43 disposed along the outer body.
Wiper fins 43 may be formed from flexible elastomeric material and project radially from plug body in such a manner that fins 43 flex to seal against the casing 11 wall as the plug 40 is lowered into the wellbore. Plug(s) 40 may be manufactured from solid materials (i.e., the nose of the plug(s) 40 are solid), and/or may be manufactured with one or more dissolvable portions or bursting portions (e.g., rupture disks/membranes).

[0058] The nose of the plug 40 may be configured to land in, and optionally latch to, a plug seat 41 formed in the upper end of inner collar 30. For example, plug 40 may interlock or mate with plug seat 41, the plug 40 being gripped or frictionally engaged with plug seat 41. Seating the plug 40 within plug seat 41 confirms position downhole and further allows the plug 40 to impose a force against plug seat 41, serving to drive the plug/seat assembly axially within the casing (e.g., to shift the collar Date Recue/Date Received 2022-01-11 30). Plug(s) 40 may be driven either mechanically or hydraulically, or via any other appropriate means known in the art. At least one annular seal 44 (0-ring) can be provided about the nose of plug 40, for sealingly engaging plug seat 41 and effectively isolating the wellbore therebelow. One or more cement plug(s) 40 may be placed .. within the subterranean wellbore as required.

[0059] The at least one plug 40 may be pumped downhole through casing 11, contacting the interior surface of the casing 11 and wiping the surrounding casing 11 wall. Initially, the nose of plug 40 lands in the plug seat 41 of inner collar 30 without displacing collar 30 ("closed position" shown in FIG. 2). In this position, the interfaces .. of the cement plug 40 nose and the annular plug seat 41 of the inner collar 30 fit together so that the faces are in face-to-face contact, and the surfaces thereof are complimentary and nestle one within the other. Inner collar 30 thus serves to anchor the at least one plug(s) 40 within casing 11 (for e.g., until frac initiation is commenced), and to prevent fluid flow through bore 12 of casing 11.

[0060] When desired, as shown in FIG. 3, cement plug 40 may serve as an actuable piston to displace inner collar 30, opening treatment fluid ports 24 (see arrows denoting fluid flow). More specifically, when fracing operations are commencing and it is necessary to open the toe of the wellbore to treatment fluids, hydraulic pressures imposed upon cement plug 40 can be used to selectively open ports 24.

[0061] To open fluid treatment ports 24, fluids may be pumped down casing 11 until the fluid flow through the assembly is blocked by plug(s) 40, causing hydraulic pressure to build up above the plug(s) 40. This increased fluid pressure acts against Date Recue/Date Received 2022-01-11 collar 30, exerting a downward force thereon. When the hydraulic pressure is sufficiently great to overcome the shear pins 27, pins 27 will shear and inner collar 30 will displace axially downwardly (i.e., both plug(s) 40 and collar 30 are shifted axially downhole). As the plug(s) 40 displace away from ports 24, the ports 24 open and, where fluid exits the assembly 10 into the formation, a drop in the pressure within the casing 11 may be observed, providing a positive indication that ports 24 are open. As would be appreciated, an operator would know and understand when plug(s) 40 and collar 30 have shifted since the pressure drop within the casing string 11 will occur at or near a pressure at which the shear pins 27 are designed to shear. Moreover, as would be appreciated, an operator would know and understand when plug(s) 40 and collar 30 have shifted, but fluids are not able to penetrate into the formation (e.g., deep shale formations). In such circumstances, operators may need to access one or more alternative mechanisms to establish a flow path into the formation.

[0062] In some embodiments, such alternative mechanisms for establishing a fluid flow path may comprise means for temporarily closing housing, collar, and plug(s) bores 22,32,42, respectively, and then opening said means to enable additional fluid flow in the casing 11. For example, operations occurring at the toe of the wellbore can require the use of any number of technologies including coiled tubing, bridge plugs, pressure tests, and perforations (for fracing operations), such technologies .. necessitating different, reliable fluid flow paths near or out of the toe, at different times, and without intervention. In some circumstances, fluid flow paths may need to be commenced after cementing has taken place (i.e., where the shoe has had displacement fluids pumped through it to displace the cement, or a "wet shoe"). It is Date Recue/Date Received 2022-01-11 thus an advantage of the present assembly 10 can provide alternative means for establishing additional fluid flow paths, such as by providing one or more cementing plug(s) 40 configured with one or more dissolvable materials, burst ports/valves, or the like.

[0063] For example, having regard to FIG. 4A, at least one cement plug(s) 40 may comprise one or more dissolvable materials and/or burst materials (ports/disks) 45 for selectively permitting fluid flow through bore 42, such flow being controlled by pressure (depending upon rupture disk rating) or over time (depending upon corrosion rates of dissolvable materials). Plug(s) 40 incorporating dissolvable or burst port(s) 45 can land within collar 30 and are operable to provide both means for ensuring pressure integrity for casing tests (where port(s) 45 are closed) as well as means for achieving fluid flow-through capability (where port(s) 45 are opened). That is, where operators need to account for operational pressures within central bore 12 of casing 11, the at least one port(s) 45 may be selectively closed. Then, where additional fluid flow through the central bore 12 of casing 11 is desired, the at least one port(s) 45 may be selectively opened. It should be appreciated that such additional port(s) 45 may be opened whether or not collar 30 has been displaced within housing 20. By varying the type or combination of closures on various ports within the present assembly 10, more selective and controlled fluid flow through the assembly 10 may be possible.

[0064] In some embodiments, alternative mechanisms of establishing additional fluid to reach the formation through selectively opened ports may be provided as a contingency where some fluid ports fail to open or become clogged, where the shoe track is plugged by cement or a cement/mud mixture, or where it is Date Recue/Date Received 2022-01-11 desired to provide additional fluids to the formation. According to embodiments, having regard to FIG. 4B, the presently improved assembly 10 may be provided where outer housing 20 is configured with one or more dissolvable materials, burst ports/valves, or the like. Outer housing 20 may comprise one or more dissolvable ports 46, radially disposed about the housing 20 sidewall, for selective removal to permit fluid flow from the assembly 10 into the formation. Should additional fluid flow from the assembly into the formation (i.e., through casing sidewall 11) be desired, the at least one dissolvable port(s) 46 may be selectively opened. It should be appreciated that such additional ports 46 may be opened whether or not collar 30 has been displaced within housing .. 20 (i.e., whether or not ports 24 are open or closed). It should also be appreciated that positioning such additional port(s) 46 in housing 20 sidewall conveniently provides a large, gravity-assisted fluid flow path directly to port(s) 46 (i.e., to provide access of fresh fluids to dissolvable ports for improved reaction thereof). By varying the type or combination of closures on various ports within the present assembly 10, more selective and controlled fluid flow from the assembly 10 into the formation may be possible.

[0065] In some embodiments, one or more burst ports may be provided in the sidewall of outer housing 20 but below the collar 30. Where such ports (e.g., 28) are made from dissolvable material, the ports may be operative to provide high pressure ratings during cementing operations, but then dissolve in time preceding operations to open initiation ports 24. As would be appreciated, however, such ports should not comprise burst ports where, for example, high back pressures are expected on the backpressure valves located in the shoe below the ports (not shown).

Date Recue/Date Received 2022-01-11

[0066] In some embodiments, where it is desired to lock collar 30 in the open position, one or more latching mechanisms may be provided. For example, having regard to FIG. 4B, a latch ring 52 may be provided about the inner surface 23 of outer housing 20 for engaging a corresponding trap ring 54 having a profile, groove, detent or trap on the outer surface 31 of collar 30. Once the collar 30 has shifted downhole within housing 20, collar 30 is positioned so as to engage the latching mechanism, i.e.
engaging the latch ring 52 in trap ring 54, holding the collar 30 in position and preventing collar 30 from actuating in reverse/uphole (i.e. ensuring ports 24 remain open). Although various latching mechanisms are shown, it should be understood that actuation of the float collar 30 within outer housing 20 may be controllably prevented by any means known in the art including, without limitation, a canted spring, a collet, or other engagement device, or may be provided independently by, without limitation, interference fit.

[0067] In other embodiments, having regard to FIGS. 6 and 7, housing 20 and collar 30 may be configured to provide anchoring means 60, such as a pin positioned within a corresponding J-slot or J-gap profile (with or without rotation of collar 30 relative to housing 20, or vice versa). As would be known in the art, such a mechanism may serve to anchor collar 30 in the open position, preventing collar 30 from inadvertently sliding back uphole (i.e. such mechanism operable in addition to, or instead of, latching mechanism). Such a mechanism may further provide controlled actuation of collar 30, while minimizing failure or debris-related jamming during latching of collar 30. In some embodiments, having regard to FIG. 7, embodiments of the present assembly 10 may further comprise one or more casing buoyancy system, Date Recue/Date Received 2022-01-11 debris subs or traps 62, positioned between the present assembly 10 and the shoe therebelow, such that fluid flowing through central bore 12 of casing 11 may clear any debris accumulated within casing 11, including glass or ceramic, burstable, frangible membrane materials contained in the casing buoyancy system, or cement. Herein, such embodiments may provide a modified collar 30 that can contain seat 41 for landing the at least one plug(s) 40, but eliminating the need for the one or more check valves 34.

[0068] In some embodiments, the present float collar assembly 10 may further provide a stop or braking mechanism for controllably preventing collar 30 from advancing too far downhole. For example, as the collar 30 is actuated downhole, it is advanced with significant force until it reaches the extent of its travel within housing 10. Such stop mechanism may be any lockdown, snap ring, collet, or other braking mechanisms as appropriate in the industry. Although not required, an effective braking system may be useful in reducing high impact loading of the assembly 10 during shifting of inner collar 30.

[0069] In other embodiments, having regard to FIG. 5, embodiments of the present assembly 10 are provided where housing 20a may be elongated to receive and house at least two cement plugs 40, such plug(s) positioned in series such that one may be received within another to provide a fluid barrier between the cement therebelow and displacement fluids thereabove. As would be appreciated, volumes of fluid (e.g. fluids to delay cement slurry from setting, often referred to as "sugar water") may be injected into the casing bore 12 in between upper and lower plug(s), or between 'burst' and 'solid' plug(s) (both being top plugs positioned above the cement), Date Recue/Date Received 2022-01-11 enabling the control of volume and types of fluids and/or fluids and slurry mixtures within the casing 11. For example, in some embodiments, where desired, one or more of the plugs 40 may comprise conventional cement plug(s), while one or more of the other plugs may comprise wiper plug(s). As described herein, the at least one lowermost plug(s) may be received within or landed in collar 30, and may serve to axially displace collar 30 within housing 20 to open treatment fluid ports 24.

[0070] In yet other embodiments, having regard to FIG. 8, embodiments of the present assembly 10 are provided where collar 30 may not displace axially within housing 20, and where the at least one cement plug(s) 40 may comprise at least one dissolvable portion 45. For example, the at least one plug(s) 40 may be a dissolvable plug, or may comprise at least one dissolvable insert therein (either at the top of or bottom/nose of plug(s) 40, such that a smaller portion of plug(s) 40 experiences pressure differentials). According to such embodiments, following primary cementing operations as described, an operator may land the at least one plug(s) 40 within collar .. 30 in order to perform a pressurized test within the bore 12 of casing 11 (e.g. in order to ensure the casing 11 will handle the pressures required for fracing operations).
Then, at a predetermined time sufficient to corrode dissolvable materials in the at least one cement plug(s) 40 (or insert therein), fluids can again be pumped downhole or to squeeze fluid out of the casing shoe, particularly where the shoe suffers from poor cement support (i.e. a wet shoe). As would be appreciated, it is an advantage that such dissolvable materials can provide for controlled volumes/flow of sugar water (e.g.
to delay the setting of cement), potassium chloride (e.g. to corrode dissolvable materials/ports), or a combination thereof (e.g. to delay cementing while corroding Date Recue/Date Received 2022-01-11 dissolvable materials/ports). As would also be appreciated, upon completion of fluid treatment through ports 24 or as otherwise desired, the present assembly 10 may be configured such that fluid ports 24 in housing 20 may be closed again by any suitable means known in the art, including, by pumping a plug, dart, ball, or other suitable obstruction known in the industry into bore 22 of housing 20.

[0071] Embodiments of the presently improved float collar assembly 10 may provide an alternative solution for operators to access the formation instead of, for example, utilizing a wet shoe. Embodiments of the presently improved float collar assembly 10 may provide an additional access point for operators to reach the formation, in addition to a wet shoe, and/or in addition to or instead of other toe sleeves known in the art. Present embodiments may advantageously provide a less tortuous flow path to the formation where fluid is required to exit out of the toe of the wellbore, e.g. at the onset or commencing of fracing operations, where plug(s) need to be pumped downhole, where coiled tubing is needed to shift bottomhole assemblies in extended reach wells, or to provide balls for ball drop completions to the toe of the wellbore. It should be readily appreciated that such advantages aim to minimize costly delays during fracing operations, providing several fluid exit locations in the toe of the well. It should also be readily appreciated that such advantages aim to provide several different types of componentry/apparatus, reducing the risk that excessive pressure will be required to pump fluid into the wellbore, and exit the wellbore at the toe. Flow rates greater than 0.5 m3/min are typically required.

[0072] Herein, methods are provided for the use of one or more conventional cement plug(s) for cementing operations, such plug(s) also functioning as a device to Date Recue/Date Received 2022-01-11 occlude a seat 41 in a collar 30, enabling a pressure differential to move collar 30 to open at least one ports 24 in outer housing 20, thereby gaining fluid access to the formation. Methods are also provided for the use of displacement fluids during the cementing operations, such fluids used to have the one or more plug(s) displace the .. cement from the shoe track to create an unobstructed path for the collar 30 to slide to the open position. Methods are also provided for the use of displacement fluids during the cementing operations, such fluids used to have the one or more plug(s) partially displace the cement from the shoe track, providing a the minimum volume of fluid required to slide collar 30 into the open position, but yet avoid a wet shoe.
Finally, .. methods are also provided for relieving displaced fluid through relief burst ports.

[0073] Although a few embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications can be made to these embodiments without changing or departing from their scope, intent or functionality. The terms and expressions used in the preceding specification have .. been used herein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and the described portions thereof.

Date Recue/Date Received 2022-01-11

Claims (20)

What is claimed is:

1. A float collar assembly comprising:
an outer tubular housing having a substantially cylindrical sidewall with an outer surface, an inner surface, and defining a central housing bore, the sidewall forming at least one fluid port extending therethrough, an inner tubular collar sealably positioned within the central housing bore, the inner collar having at least one valve for controlling fluid flow therethrough, one or more mechanical connectors releasably connecting the inner collar to the outer housing, wherein, when connected, the inner collar is retained in a first closed position preventing fluid flow through the at least one fluid ports, and wherein, when disconnected, the inner collar is shifted within central housing bore to a second open position permitting fluid flow through the at least one fluid ports.

2. The assembly of claim 1, wherein the at least one fluid ports are radially positioned about the housing sidewall.

3. The assembly of claim 1, wherein the one or more mechanical connectors comprises shear pins.

4. The assembly of claim 1, wherein the one or more mechanical connectors comprises an interlocking profile between the inner collar and outer housing.

5. The assembly of claim 1, wherein the at least one valve comprises a check valve.

Date Recue/Date Received 2022-01-11

6. The assembly of claim 1, wherein the inner collar is configured to receive at least one cement plug.

7. The assembly of claim 5, wherein the cement plug may be solid.

8. The assembly of claim 5, wherein the cement plug may comprise one or more dissolvable or burst portions.

9. The assembly of claim 1, wherein the outer housing sidewall may further comprise one or more dissolvable or burst portions.

10. The assembly of claim 1, wherein the assembly is operably connected to a casing string.

11. The assembly of claim 1, wherein the assembly is positioned at or near a toe end of a subterranean wellbore.

12.A method for completing a subterranean wellbore with a casing string positioned within the wellbore, the method comprising:
providing a float collar assembly operably connected to the casing string, the float collar assembly having an outer tubular housing mechanically connected to an inner tubular collar, the inner collar sealably retained in a first closed position within the housing covering at least one fluid flow port in the housing to prevent fluid flow therethrough, and having at least one valve for preventing fluid flow through the assembly, running the casing string into the wellbore with the assembly in the first closed position, and Date Recue/Date Received 2022-01-11 disconnecting the inner collar from the outer housing, shifting the inner collar to a second open position uncovering the at least one fluid flow ports in the housing to permit fluid flow therethrough.

13. The method of claim 12 wherein, prior to disconnecting the inner collar from the outer housing, the method comprises introducing cementing fluids into the casing string to cement the casing to the subterranean wellbore.

14.The method of claim 13, wherein the cementing fluids are introduced at fluid pressures sufficient to open the at least one valve in the inner collar without disconnecting the inner collar from the outer housing.

15. The method of claim 14, wherein the method further comprises introducing at least one cement plug into the casing string to land in the inner collar.

16. The method of claim 15, wherein the method comprises increasing fluid pressures above the at least one cement plug to hydraulically disconnect the inner collar from the outer housing.

17.The method of claim 15, wherein the method comprises mechanically disconnecting the inner collar from the outer housing.

18.The method of claim 13, wherein the method further comprises introducing treatment fluids into the casing string and out of the assembly through the at least one fluid ports.

19.The method of claim 14, wherein the at least one cement plug comprises a dissolvable or burstable portion, and the method further comprises passing treatment fluids through the at least one cement plug.
Date Recue/Date Received 2022-01-11

20. The method of claim 12, the method comprising running the assembly in the first closed position during casing and cementing operations and shifting the inner collar to the second open position during wellbore treatment operations.

Date Recue/Date Received 2022-01-11