Patent Application
20240410251
None.
This disclosure relates generally to oilfield downhole valves tools, and more particularly to methods and apparatus for converting a valve assembly from bi-directional to unidirectional when in a wellbore.
Drawings of the preferred embodiments of the present disclosure are attached hereto so that the embodiments of the present disclosure may be better and more fully understood:
After a wellbore is drilled through a formation, it is typical to line the wellbore with a tubular, such as a casing. To prevent the casing from moving within the wellbore, the casing annulus is filled with cement during a cementing operation. As the casing is run in it is typically filled with a fluid, such as drilling mud. It is common to place a float assembly, such as a float shoe or float collar, at or near the bottom of the casing string. The float assembly has one or more unidirectional float valves which allow fluid to pass from the casing string into the annulus but prevent flow from the annulus back into the casing string. These float valves can serve two purposes.
While running the casing string into the wellbore, it is common to use the wellbore fluid to sustain a portion of the weight of the casing string by floating the casing string in the wellbore fluid. The float assembly prevents fluid flow into the bottom of the string, allowing the string to float in the fluid present in the wellbore. Once in position in the wellbore, the float valves allow the flow of fluids during, for example, a cementing operation, such as spacer fluid, cement, displacement fluid and the like, as they are pumped down the casing string, through the unidirectional float valves and into the wellbore annulus. The float valves keep these fluids from flowing from the annulus back into the casing string.
However, in some instances it is preferable to insert the casing string without floating the string. In such a case, the unidirectional float valves are a hinderance to running in the string. Instead, a bidirectional valve is needed, allowing fluid flow up the string during run in. A convertible valve acts as a bidirectional valve during run in, and then converts to a unidirectional valve, like a typical float valve, once positioned downhole. This allows fluid flow upwards during run in but prevents flow back into the string during later pumping operations. Convertible valves, or auto-fill valves, are known in the industry and typically rely on a flapper valve which is maintained in an open position during run in, allowing automatic filling of the casing string. The valve is converted to a unidirectional valve, by releasing the flapper from the open position, with the flapper then biased towards the closed position.
The terms “above” and “below, and “behind” and “in front,” are used herein without respect to whether the wellbore is vertical or horizontal. Similarly, the terms “uphole,” “downhole,” and the like are used without respect to whether the wellbore is vertical or horizontal. For example, a fluid, tool or the like, said to be above, behind, or uphole of another tool is relatively closer to the wellhead, or having entered the wellbore later, whether along a horizontal or vertical portion of the wellbore. As persons of skill in the art will understand, the disclosures herein are applicable in horizontal and vertical wells.
The valve assembly 102 has a housing 104 defining a generally longitudinal flow bore 106 therethrough. The upper end of the housing 104 includes a connection 108 for connecting the housing to a tubular as part of a casing, liner or work string, for example. The connection can be a threaded connection or other connection as known in the art.
The valve assembly 102 includes an upper valve 110 and a lower valve 130, both positioned in the housing 104, arranged in series. The upper and lower valves 110 and 130 are plunger type valves. Plunger type valves offer improved reliability over flapper valves, for example, which tend to be used in large bore autofill valve applications. Further, plunger type valves are, for the same performance, smaller and lighter than the flapper type valves typically used in such applications. This leads to reduced drill out times and less debris when the valve assemblies are drilled out after use.
The upper valve 110 has an upper valve element 112 with an upper valve head 114 and an upper valve stem 116. An upper valve seat 118 is defined in the housing 104. The seat can be defined on the housing wall or on an insert 126 in the housing 104, as shown. The upper valve head 114 of the upper valve element 112 cooperates with the upper valve seat 118. The upper valve element is moveable between a closed position, wherein the upper valve head 114 sealingly engages the upper seat 118, and an open position wherein the upper valve head is spaced apart from the upper seat. An upper valve stem guide 120 guides reciprocating movement of the upper valve stem 116, provides a shoulder for the biasing mechanism 122, and limits downward movement of the upper valve element 112. The biasing mechanism 122, shown as a spring, biases the upper valve element towards the closed position. When in the open position, a flow path 124 allows fluid flow past the upper valve 110.
The lower valve 130 has a lower valve element 132 with a lower valve head 134 and a lower valve stem 136. A lower valve seat 138 is defined in the housing 104. The seat can be defined on the housing wall or on an insert 126 in the housing 104, as shown. The lower valve head 134 of the lower valve element 132 cooperates with the lower valve seat 138. The lower valve element is moveable between a closed position, wherein the lower valve head 134 sealingly engages the lower seat 138, and an open position wherein the lower valve head is spaced apart from the lower seat. A lower valve stem guide 140 guides reciprocating movement of the lower valve stem 136, provides a shoulder for the biasing mechanism 142, and limits downward movement of the lower valve element 132. The biasing mechanism 142, shown as a spring, biases the lower valve element towards the closed position. When in the open position, a flow path 144 allows fluid flow past the lower valve 130. Since the upper and lower valve elements are tied together, in some embodiments the biasing assembly acts against only one valve element.
The exemplary insert 126 provides a housing and seats for the upper and lower valve heads 114 and 134, respectively, can be fixedly attached to the valve housing 104 or rotationally attached, allowing for rotation of the valve assembly about a longitudinal axis. A fixed attachment tends to make drilling out of the valve assembly less problematic.
The upper and lower valve elements 112 and 132, respectively, are connected together, such as by a connection element 150, such that the valve elements move in unison. That is, when one valve is moved to its closed position, both valves are moved to their closed positions, as seen in
The lower end 152 of the valve assembly 102 is attached to a retainer assembly 300. The retainer assembly 300, in some embodiments, can generally be considered to be a caged ball, shear tube releasably attached to the valve assembly 102. Other embodiments are disclosed herein as well. The retainer assembly has a housing 302 defining a chamber 303, inside of which is a free-floating occluding device 304. It is understood that the occluding device can be of various shape and size. In the exemplary embodiment shown, the occluding device is a ball. The occluding device 304 cooperates with a seat 306 defined in the retainer housing 302. The occluding device 304, in response to downward fluid flow through the housing, seats on seat 306. The seat 306 defines a bore 308 therethrough allowing fluid flow out the lower end 310 of the housing 102 when the occluding device 304 is unseated.
In some embodiments, the retainer assembly 300 is releasably attached to the valve assembly 102. In the embodiment shown, the upper end 312 of the retainer housing 302 is releasably attached to the lower end 152 of the valve housing 104. The releasable attachment can be any known in the art, such as shear pins 314, shear ring, snap ring, etc. The shear pins 314 extend through the valve housing lower end 152 and the retainer housing upper end 312.
A retainer device 320 is operable to maintain the valve assembly 102, at both upper valve 110 and lower valve 130, in the open, bi-directional configuration, and to release the valve assembly 102 to a unidirectional configuration, wherein the valve assembly, at both upper and lower valves 110 and 130, are in a biased closed position. To that end, the retainer device is releasably attached to, for example, the lower valve element 132.
An exemplary retainer device 320 is in seen orthogonal view in
The retainer device 320 performs two primary functions: maintaining the valve assembly in the bi-directional configuration during run-in; and releasing the valve assembly to a unidirectional configuration, wherein the valve assembly is biased closed for use in downhole operations, such as cementing for example.
To release the valve assembly, the retainer device 320 breaks a connection to the valve assembly 102 or the valve assembly housing 104. In the exemplary arrangement seen in
It is understood that the retainer device 320 can be designed to release at other points and still perform the same functions. In the embodiments seen in
Further, those of skill in the art will recognize that the retainer device 320 itself can define a release mechanism. That is, the device can be designed to release or shear at a preselected location on the device. For example, the retainer device 320 can define a release mechanism on the retainer rod 322, such that the rod 322 shears to release the valve assembly from its retained position, with the retainer body 320 fixedly attached to the retainer housing 302. In such an embodiment, the retainer housing 302 is releasably attached to the valve housing 104 by a separate release mechanism. Those of skill in the art will recognize that the retainer device 320 can take a different shape and size than the exemplary embodiment shown.
In the embodiment seen in the figures, the retainer device 320 also performs the function of maintaining the occluding device 304 in the retainer housing 302. That is, during run-in, fluid flow upwards through the assemblies will tend to force the occluding device upwards towards the upper end 312 of the retainer housing 302. The occluding device 304 is prevented from movement into the valve assembly housing 104 by the retainer body 324. Those of skill in art will recognize that a separate obstruction can be employed to control and limit upward movement of the occluding device, such as a pin extending across the housing.
In the exemplary embodiment seen in the figures, the retainer housing 302 defines one or more radial flow ports 340 allowing fluid flow downward through the retainer assembly even when the occluding device 304 is seated on seat 306. The flow ports 340 allow downward fluid flow up to a preselected flow rate without building sufficient pressure above the occluding device to cause the release mechanism to actuate. Flow through the ports 340 exits the housing 302 into a wellbore annulus defined between the housing and the wellbore. For example, the ports 340 can be designed to allow a relatively low flow rate of around 1.5 to 3.0 barrels per minute without actuating the retaining mechanism. When the pump rate is increased to a preselected rate, such as 4.0 barrels per minute, pressure in the retainer housing 302 above the occluding device 304 rises to a preselected pressure at which point the occluding device 304, pushing downward on the seat 306 shears the shear pins 314, thereby releasing the retainer housing 302 from the valve assembly housing 104 and the retainer device 320 from the retainer housing 302 and the valve assembly housing 104. In another embodiment, the ports 340 are designed to allow a relatively high flow rate of around 3-4 barrels per minute without actuating the retaining mechanism. When the pump rate is increased above that rate, such as to 5-8 barrels per minute, pressure in the retainer housing 302 above the occluding device 304 rises to a preselected pressure at which point the occluding device 304, pushing downward on the seat 306 and the retainer housing 302, shears the shear pins 314.
In use, the valve assembly 102 and retainer assembly 300 are attached to a casing or other tubular string at a well site. The valve and retainer assemblies are run downhole with the valve assembly in the bi-directional configuration, with both the upper and lower valves 110 and 130 in the open position allowing fluid flow during run-in, as seen in
Once the tools are in position in the wellbore, additional operations may be performed. For example, various fluids may be pumped down the casing string, through the valve assembly and the retainer assembly as seen in
In the embodiment shown, the radial flow ports 340 allow fluid flow downward through the valve assembly 102, into the retainer housing 302 and out the flow ports 340. The fluid flows through bore 106, open upper valve 110 at flow path 124, open lower valve 130 at flow path 144, and out the valve assembly at lower end 152. Flow continues past retainer device 320 via flow paths 328 and into retainer housing 302. Here, flow passes through the bore 308 in seat 306 until the occluding device 304 seats. In embodiments allowing flow at a preselected flow rate, bypassing the seated occluding device, flow will continue through, for example, radial ports 340 and into the wellbore. Flow through such ports can be useful for flowing debris, such as cuttings or formation rock from a weak formation, out of the casing string, for example.
When it is desired to convert the convertible valve assembly to a unidirectional valve assembly, fluid is pumped down the casing string, through the open valves 110 and 130 and into the retainer housing 302. Downward flow seats the occluding device 304 on seat 306. Fluid flows out flow ports 340, where present, into the wellbore annulus. Fluid flow may continue through ports 340 up to a preselected rate without actuating the retaining assembly. Pressure is built up in the retainer housing 302 above the occluding device 304 to a pressure preselected to actuate the retainer assembly.
In the embodiment shown, a preselected pressure actuates the release mechanism, namely, shear pins 314. The shear pins 314 shear, releasing the retainer housing 302 from the valve assembly housing 104 and releasing the retainer device 320 from the valve assembly housing 104 and retainer housing 302.
In the embodiment shown, the retainer device 320 separates from the retainer housing 302 and the valve assembly housing 104 at shear pins 314. This releases the valve assembly to the unidirectional configuration seen in
The retainer assembly 300, in main part, drops from the end of the casing string into the wellbore (or, if present, shoe assembly), as seen in
In some embodiments, the retainer device 320 is released at other points than the shear pins 314. The retainer device 320 itself can define a release mechanism, in which case the retainer device 320 releases or shears at a preselected location on the device. For example, the retainer device 320 can shear at a point on the retainer rod 322, such that the rod 322 releases from the lower valve element 132. In such a case, the remainder of the retaining device 320 falls into the wellbore.
In the unidirectional configuration, as seen in
When desired, the valve assembly 102 can be drilled out, clearing the casing string of restrictions.
Those of skill in the art will recognize that the retaining assembly, or parts thereof, can be positioned above the valve assembly. For example, the retaining housing can be positioned above the valve assembly. The occluding object can be flowed down from the surface or caged within the housing. Pressure above the occluding device causes movement of the seat, shearing of a shear mechanism which releases the retainer device 320 from, in this case, the upper valve element 112, thereby releasing the valve assembly to move to the unidirectional configuration.
The embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. 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 of the present disclosure. The various elements or steps according to the disclosed elements or steps can be combined advantageously or practiced together in various combinations or sub-combinations of elements or sequences of steps to increase the efficiency and benefits that can be obtained from the disclosure. It will be appreciated that one or more of the above embodiments may be combined with one or more of the other embodiments, unless explicitly stated otherwise. Furthermore, no limitations are intended to the details of construction, composition, design, or steps herein shown, other than as described in the claims.
| Number | Date | Country | |
|---|---|---|---|
| 63507295 | Jun 2023 | US |
