Patent Application
20220307348
Hydrocarbon fluids such as oil and gas are produced from wells drilled into an underground hydrocarbon formation. Wells are drilled to great depths into a hostile environment of temperature, pressure, and fluid chemistry, so the industry is constantly in pursuit of reliable ways to control downhole equipment from the surface. A variety of downhole tools that are used to construct and service wells rely on mechanical actuation. These tools may be lowered on a tubing string and then actuated to perform some tool function, such as closing a valve. One type of actuation is mechanical actuation involving axial movement of a piston. This type of actuation can be convenient and reliable because it allows a downhole tool to be controlled by personnel or machinery located above ground by supplying pressurized hydraulic fluid downhole from the surface.
An example of a downhole tool that may be controlled by mechanical actuation is a subsurface safety valve. After the well is drilled and completed, the hydrocarbon fluids produced from the formation may be conveyed to surface through production tubing installed downhole. Surface-controlled subsurface safety valves (SSSVs), for example, are used to selectively close off lower portions of the flowbore of a production tubing string in the event of an emergency. These valves can then be reopened later when the emergency has been remedied and it is desired to reestablish flow. For example, in response to an accident, a control action at the surface, or otherwise a decrease of hydraulic fluid pressure, the safety valve can be closed to seal the flow of fluid from the formation.
These drawings illustrate certain aspects of some of the embodiments of the present disclosure and should not be used to limit or define the method.
The present disclosure includes an actuator and method for a downhole tool that provides a clearance path for viscous fluids to bypass a wiper to prevent them from retarding component movement within the downhole tool. The wiper normally helps keep out fluids and contaminants from entering the space between certain components (e.g., a flow tube) and the tool body. The clearance paths are provided to allow for any trapped fluids or contaminants to bypass the wiper when actuating the downhole tool.
Specific example embodiments include a subsurface safety valve (SSV) having a flow tube for actuating a valve closure element and a reduced-diameter clearance paths defined in an upper flow tube extension. The flow tube is moveable between a first axial position (valve open) to a second axial position (valve closed). A wiper ring between the flow tube and tool body engages respective shoulders on the flow tube in the first and second axial positions to keep out fluid and contaminants when in the first and second axial positions. The clearance paths axially between the shoulders allow viscous fluid and other contaminants to pass under the wiper as the flow tube moves between the first and second axial positions.
A number of different example configurations are disclosed for the clearance paths. One example includes axially-extending channels along an external flow tube profile. Another example includes axially-extending flats that cut across a circular outer portion of the external flow tube profile. Yet another example includes a continuous reduced-diameter portion between the shoulders.
The wellbore 16 may be drilled along a desired wellbore path to reach a target formation, such as to avoid non-desirable formation features, to minimize footprint of the well at the surface, and to achieve any other objectives for the well. Although the illustrated portion of the wellbore 16 is vertically downward, the wellbore may deviate in any direction with varying azimuth and inclination, which may result in sections that are vertical, horizontal, angled up or down, and/or curved. The term uphole generally refers to a direction along the wellbore path toward the surface 14, and the term downhole generally refers to a direction toward the bottom of the well, without regard to whether a feature is vertically upward or vertically downward with respect to a reference point.
The derrick 20 or other support structure may be used to help support and manipulate the axial position of a tubing string 24 such as to raise and lower it within the wellbore 16. The tubing string 24 may be made up of segments of oilfield tubulars such as drill pipe, casing, production tubing, or other tubular segments, and having any of a variety of tools for performing wellbore operations, such as drilling, completion, stimulation, or production. The tubing 24 string may serve various functions, such as a work string to lower and retrieve tools, completion or production tubing to convey fluids from or to the surface 14, and to support the conveyance of communication and power during wellbore operations. When a wellbore operation is to be performed, the tubing string may be progressively assembled on site and lowered into the wellbore, i.e., run/tripped into the wellbore 16. When a wellbore operation is complete, or when it becomes necessary to exchange or replace tools or components of the work string, the tubing string 24 in some cases may be raised or fully removed from the wellbore, i.e., tripped out of the hole.
In an example of a completion operation, the tubing string 24 may comprise a work string used to lower a completion string into the wellbore, including intervals of casing, and cement the casing in place. In an example of a formation stimulation operation, the tubing string 24 may comprise a frac tubing string for conveying proppant-laden fluids used in hydraulically fracturing the formation, or other treatment fluids and/or chemicals such as an acidizing treatment, to stimulate the flow of hydrocarbons from the formation 18. In an example of a production operation, the tubing string 24 may comprise production tubing lowered into the wellbore 16 and coupled to a lower completion string 26 above a production zone, so formation fluids such as oil and gas may flow through the production tubing to surface. In any of these examples, fluid may either flow from the well
Aspects of the downhole tool 30 are generalized or schematically illustrated for discussion purposes in
A generally tubular actuator element referred to as the flow tube 34 is moveably disposed within the through bore of the actuator body 32. The generally tubular structure of the flow tube 34 conveys fluid through the downhole tool 30 to and/or from the tubing string 24. The flow tube 34 is also axially moveable within the actuator body 32, and may be driven by a piston 36 controlled from the surface 14 hydraulically, electrically, or otherwise, to actuate the tool 30. Actuating the tool 30 may involve using the axial displacement of the flow tube 34 to perform some tool function. For example, if the downhole tool 30 comprises a valve, the tool function may comprise moving a valve element from an open position to a closed position or vice-versa, in response to axial movement of the flow tube 34 within the actuator body 32.
An example of a mechanically-actuatable downhole tool is discussed below. However, one of ordinary skill in the art will appreciate that other downhole tools may be similarly actuated in accordance with this disclosure. Other such tools may include, for example, downhole internal control valves (ICVs), flow control equipment, and circulation and production sleeves.
The flapper valve 50 comprises an assembly of a valve closure element, embodied in this example as a flapper 52 and a seal 54 located near the lower end of the SSV 40. The flapper 52 is pivotable about a hinge 55 between the open position shown in
An actuator element referred to as the flow tube 60 is axially moveable within the through bore 49 of the tool body 48. The flow tube 60 has an upper end 62, a lower end 64, and an interior flow bore 63 therebetween to provide fluid flow. The flow tube 60 is also axially moveable when actuating the SSV 40. Any of a variety of actuator types suitable for axially displacing the flow tube 60 may be used. In this embodiment, downward axial movement of the flow tube 60 is imparted by a hydraulically-operated piston 66 disposed between the flow tube 60 and a spring housing 46 of the tool body 48. A spring 67 within the spring housing 46 may bias the flow tube 60 upward, which biasing force is overcome when a force is applied downwardly by the piston 66.
In
The flow tube 60 includes a flow tube extension 100. A portion of the flow tube 60 from which the flow tube extension 100 extends is wider than the portion of the flow tube 60 below the flow tube extension 100. The flow tube 60 below the flow tube extension 100 rides in a wider portion of the tool body 48 than the flow tube extension 100, with an annular volume 102 defined between the flow tube extension 100 and the wider portion of the tool body when the flow tube is in the first axial position. When moving the flow tube 60 toward the second axial position (to the left in
An external flow tube profile 70 is formed on the flow tube 60 to mitigate the possibility of the flow tube 60 becoming stuck or slowing response time due to any viscous fluid or contaminants in the annulus 68. In this example, the external flow tube profile 70 is formed on a flow tube extension 100 of the flow tube 60. Generally, the external flow tube profile 70 is formed so that the wiper 79 is engaged with the outer diameter (OD) of the flow tube in the first axial position corresponding to the open valve (as in
Three example positions 81, 82, 83 of the wiper ring relative to the flow tube extension 100 are shown in phantom lines, depending on the axial position of the flow tube 60. The first wiper ring position 81 corresponds to the flow tube being in the first axial position (open valve), wherein the wiper ring engages the first shoulder 72 and flow across the wiper is minimized. The second wiper ring position 82 corresponds to the flow tube being in the second axial position (closed valve), wherein the wiper ring engages the second shoulder 72 and flow across the wiper is also minimized. The third wiper ring position 83 corresponds to the wiper ring being in-between the first and second shoulders 72, 74, wherein viscous fluids can more easily pass under the wiper ring at each channel 78 as indicated at arrows 84.
Accordingly, the present disclosure provides a downhole tool, actuator, and method that utilize clearance paths for viscous fluids and other contaminants to bypass a wiper during actuator. A number of different external flow profiles and clearance paths are possible, of which the above are just some examples. Reliability is maintained, which is especially important for safety equipment such as subsurface safety valves. The disclosed tool, actuator, and method may include any of the various features disclosed herein, including one or more of the following statements.
Statement 1. A subsurface safety valve, comprising: a tool body positionable in a wellbore and having an upper end for coupling to a tubing string, a lower end, and a through bore between the upper and lower ends for conveying fluid; a valve closure element coupled to the lower end of the tool body and moveable between an open position and a closed position; a flow tube disposed in the tool body and axially moveable between a first axial position putting the valve closure element in the open position and a second axial position allowing the valve closure element to move to the closed position, the flow tube including an interior flow bore for conveying the fluid from the tubing string; and an external flow tube profile formed on the flow tube including an upper shoulder for engagement with a wiper in the first axial position, a lower shoulder for engagement with the wiper in the second axial position, and a clearance path between the upper and lower shoulders for allowing viscous flow past the wiper when the flow tube is in-between the first and second axial positions.
Statement 2. The subsurface safety valve of Statement 1, wherein the clearance path comprises a plurality of axially-extending, circumferentially-spaced channels along the external flow tube profile between the upper and lower shoulders.
Statement 3. The subsurface safety valve of Statement 1 or 2, wherein the clearance path comprises a plurality of axially-extending flats between the upper and lower shoulders.
Statement 4. The subsurface safety valve of any of Statements 1-3, wherein the clearance path comprises a continuous, reduced-diameter portion between the upper and lower shoulders.
Statement 5. The subsurface safety valve of any of Statements 1-4, wherein an annular gap between the flow tube and the wiper is at least 10 mm along the clearance paths.
Statement 6. The subsurface safety valve of any of Statements 1-5, further comprising: a flow tube extension extending from the flow tube; an upper shoulder along the flow tube extension defining the upper shoulder; and a lower shoulder along the flow tube extension defining the lower shoulder.
Statement 7. The subsurface safety valve of any of Statements 1-6, wherein the valve closure element comprises a flapper pivotable to an open position in response to positioning of the flow tube in the first axial position and to a closed position in response to positioning of the flow tube in the second axial position.
Statement 8. The subsurface safety valve of any of Statements 1-7, wherein the tool body comprises a top sub and a bottom sub for releasably coupling the tool body to a completion string.
Statement 9. The subsurface safety valve of Statement 1, wherein the flow tube comprises a flow tube extension on an upper end defining the clearance path of the external flow tube profile, wherein the wiper is positioned in an annulus between the flow tube extension and the tool body.
Statement 10. The subsurface safety valve of Statement 9, wherein a portion of the flow tube from which the flow tube extension extends is wider than the flow tube extension and rides in a wider portion of the tool body than the flow tube extension, with an annular gap defined between the flow tube extension and the wider portion of the tool body when the flow tube is in the first axial position, and wherein the flow tube fills at least a portion of the annular gap when moving to the second axial position to urge trapped fluid out of the annular gap and across the wiper.
Statement 11. The subsurface safety valve of any of Statements 1-10, wherein the wiper comprises a wiper ring supported on a wiper seat.
Statement 12. A downhole tool actuator, comprising: an actuator body disposable in a wellbore and having an upper end for coupling to a tubing string, a lower end, and a through bore between the upper and lower ends for conveying fluid; a flow tube disposed in the actuator body and axially moveable within the actuator body between a first axial position and a second axial position for actuating a downhole tool when coupled to the actuator body, the flow tube including an interior flow bore for conveying fluids from the tubing string through the actuator body; and an external flow tube profile defined on the flow tube including an upper shoulder for engagement with a wiper in the first axial position, a lower shoulder for engagement with the wiper in the second axial position, and a clearance path between the upper and lower shoulders for allowing viscous flow past the wiper when the flow tube is moved between the first and second axial positions.
Statement 13. The downhole tool actuator of Statement 12, wherein the tool comprises a valve including a moveable closure element moveable by the flow tube between an open position and a closed position.
Statement 14. The downhole tool actuator of Statement 12 or 13, wherein the clearance path comprises a plurality of axially-extending, circumferentially-spaced channels along the external flow tube profile between the upper and lower shoulders.
Statement 15. The downhole tool actuator of any of Statements 12-14, wherein the clearance path comprises a plurality of axially-extending flats between the upper and lower shoulders.
Statement 16. The downhole tool actuator of any of Statements 12-15, wherein the clearance path comprises a continuous, reduced-diameter portion between the upper and lower shoulders.
Statement 17. A method of operating a downhole tool, the method comprising: lowering the downhole tool into a wellbore on a tubing string; flowing a fluid through the tubing string and through a flow tube with the flow tube in a first axial position within a tool body; blocking flow between the flow tube and the tool body with a wiper while in the first axial position; moving the flow tube from the first axial position to a second axial position to actuate the downhole tool; and while moving the flow tube to the second axial position, passing fluid trapped between the flow tube and a body of the downhole tool under the wiper along a reduced-diameter clearance path between the flow tube and the tool body.
Statement 18. The method of Statement 17, wherein the step of passing fluid trapped between the flow tube and a body of the downhole tool under the wiper comprises passing the trapped fluid along a plurality of axially-extending, circumferentially-spaced channels along the flow tube.
Statement 19. The method of Statement 17 or 18, wherein the step of passing fluid trapped between the flow tube and a body of the downhole tool under the wiper comprises passing the trapped fluid along a plurality of axially-extending flats along the flow tube.
Statement 20. The method of any of Statements 17-19, wherein the step of passing fluid trapped between the flow tube and a body of the downhole tool under the wiper comprises passing the trapped fluid along a continuous, reduced-diameter portion of the flow tube.
For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values even if not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.
Therefore, the present embodiments are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present embodiments may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Although individual embodiments are discussed, all combinations of each embodiment are contemplated and covered by the disclosure. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure.
