Patent Application
20200190944
A subterranean safety valve is a type of failsafe device configured to prevent catastrophic failure by shutting-in a well when other means of control are compromised. While typically required in offshore wells, such safety valves are increasingly finding application in onshore, or land-based, wells where positive control of the well is desirable due to the threat of unexpected failures, vandalism, terrorism, or even theft. Subterranean safety valves are more easily installed when the well is initially being completed. Conventionally, a tubing-retrievable safety valve is run into the well while the drilling rig is on the wellsite. The tubing-retrievable safety valve is typically deployed in the annular space between the well casing and the production tubing. During production activities, the safety valve is hydraulically actuated into the open, or producing, state by a surface-based pump that communicates hydraulic pressure, via a port of the wellhead, to the safety valve deployed in the well. When the hydraulic pressure is removed, the safety valve closes. However, in some instances, when the use of a safety valve is not contemplated in advance, the well may already be drilled, completed, and may even have been producing for a period of time. At this point, it is difficult to install a safety valve because the drilling rig is typically no longer onsite, the wellhead has no paths of hydraulic communication, and the production tubing is already deployed within the well. While re-completing the well may be possible, it can be logistically and cost prohibitive and is rarely done in the field for that reason. Since the Deepwater Horizon incident, many operators are now requiring the use of safety valves in all wells, including land-based wells. However, the tubing-retrievable safety valves conventionally used are prone to failure over time, presenting a substantial risk to the safety of personnel and the environment.
According to one aspect of one or more embodiments of the present invention, a surface-controlled wireline-retrievable safety valve includes a seat housing having a plurality of flow ports that is configured to house a hard seat. A closure device has a plurality of equalization ports, is disposed within the seat housing, and is configured to controllably move off the hard seat and expose the plurality of flow ports to a central lumen of the safety valve under hydraulic actuation. A power piston having a shoulder portion is attached to the closure device and the shoulder portion is disposed within a hydraulic chamber housing forming a differential area. A hydraulic actuation port may be configured to receive hydraulic actuation fluid from a surface pump. A hydraulic passage may be configured to convey the hydraulic actuation fluid from the hydraulic actuation port to the differential area via a hydraulic access port. Under hydraulic actuation, hydraulic fluid in the differential area causes the power piston to compress the power spring and move the closure device off the hard seat exposing the plurality of flow ports to the central lumen of the safety valve.
Other aspects of the present invention will be apparent from the following description and claims.
One or more embodiments of the present invention are described in detail with reference to the accompanying figures. For consistency, like elements in the various figures are denoted by like reference numerals. In the following detailed description of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention. In other instances, well-known features to one of ordinary skill in the art are not described to avoid obscuring the description of the present invention. For purposes of clarity, as used herein, top or upper refer to a portion or side that is closer, whether directly or in reference to another component, to the surface above a wellbore and bottom or lower refer to a portion or side that is closer, whether directly or in reference to another component, to the bottom of the wellbore.
For safety and environmental reasons, a conventional downhole safety valve is typically installed during initial completion activities as a failsafe device configured to fail in the closed state such that production flow is halted whenever positively applied hydraulic actuation from the surface is removed. When a tubing-retrievable safety valve deployed within a well fails, for whatever reason, production is halted, and the operator may re-complete the well at substantial expense or run a wireline-retrievable safety valve into an inner diameter of the failed tubing-retrievable safety valve in an effort to safely continue production, albeit possibly at a reduced flow rate. A conventional wireline-retrievable safety valve may be run into the well on a lock that locates the wireline-retrievable safety valve within a desired location of the failed tubing-retrievable safety valve. The conventional wireline-retrievable safety valve typically includes packing elements that isolate the original hydraulic actuation used to control the tubing-retrievable safety valve. The process of opening up the original hydraulic actuation of the tubing-retrievable safety valve for use with the wireline-retrievable safety valve is typically referred to as communication. Communication is typically performed by cutting, punching, shifting sleeves, breaking hydraulic fittings, or other such means that are well-known in the industry and are not discussed herein. Once hydraulic communication has been achieved, a surface-driven pump is used to pump hydraulic actuation fluid through the original hydraulic actuation passage of the tubing-retrievable safety valve to the wireline-retrievable safety valve to hydraulically actuate the wireline-retrievable safety valve. While the conventional wireline-retrievable safety valve reduces the flow rate of production fluids, it allows such wells to continue producing after failure of the tubing-retrievable safety valve without the attendant cost of an expensive re-completion. As previously discussed, the conventional wireline-retrievable safety valve is a failsafe device that is closed by default and requires the positive application of hydraulic pressure to open a flapper that permits production flow through the safety valve. In the event of a failure or catastrophic event, once the hydraulic actuation is lost, the energy stored in a power spring disposed above the flapper of the wireline-retrievable safety valve causes the safety valve to close, thereby safely halting production.
However, conventional wireline-retrievable safety valves have a number of shortcomings that are problematic. For example, because of the design of conventional wireline-retrievable safety valves, the requirement for a large inner diameter and thus higher production limits the amount of space available above the flapper in the top part of the safety valve to package stored energy, typically in the form of a power spring. As such, the amount of stored energy, which is used to offset the increased hydraulic head pressure, limits the depth setting of the wireline-retrievable safety valve within the well. Moreover, even if the stored energy above the flapper in the top part of the safety valve were sufficient to overcome the increased hydraulic head pressure with increased depth, it would necessitate a reduction in the inner diameter of the safety valve, which would result in substantially reduced production flow rates. In addition, conventional wireline-retrievable safety valves use a soft seat to ensure that the flapper forms a proper seal that halts production flow. Soft seats are prone to failure over time resulting in leakage that could result in catastrophic failure of the safety valve. In addition, conventional wireline-retrievable safety valves are constrained by the depth in which they may be deployed and actuated. As discussed above, conventional wireline-retrievable safety valves require the positive application of hydraulic pressure to compress a power spring disposed above the flapper to controllably open the safety valve when production flow is desired. If the safety valve is deployed at a depth that exceeds the ability of the hydraulic actuation to overcome the hydrostatic head pressure to compress the power spring disposed above the flapper, the safety valve cannot be opened, thereby preventing production flow. In an effort to increase the installation depth at which such conventional safety valves may operate, various flapper, equalizing darts, and equalizing dart spring designs have been developed that attempt to reduce the amount of hydraulic actuation required to open the safety valve. Notwithstanding, conventional wireline-retrievable safety valves remain limited at the depth at which they may be deployed.
Accordingly, in one or more embodiments of the present invention, a surface-controlled wireline-retrievable safety valve stores the energy used to close the closure device of the safety valve below the closure device. This allows for a significant increase in the potential stored energy that can be incorporated into the valve. This additional stored energy may be used to offset the increased hydraulic head pressure at depth, therefore enabling use of the safety valve at greater depths than conventional safety valves that store the potential energy above the closure device in the top part of the safety valve. In addition, hydraulic differential pressure across the closure device from below is more robustly and automatically equalized than conventional flapper equalization designs that have low seating forces. The seating force of the equalization ports of the claimed invention, when the safety valve closes, is driven by the force of the stored potential energy, or compressed power spring, rather than a low force flapper dart spring typically found in conventional wireline-retrievable safety valves. Advantageously, the surface-controlled wireline-retrievable safety valve may be run deeper than conventional wireline-retrievable safety valves because the hydraulic actuation required to actuate the safety valve is reduced as compared to conventional wireline-retrievable safety valves. In addition, because there is never a need to go through the safety valve with auxiliary tools during operation, the power spring may be disposed below the closure device which, in addition to providing increased installation depth, substantially improves the production flow rate achieved. The design of the closure device eliminates the need for a soft seat and a flapper, further improving the quality and productive life of the seal achieved.
Safety valve 100 may include a seat housing 136 having a plurality of flow ports 137 disposed about an outer surface. Seat housing 136 may house a hard seat (not shown), a closure device (not shown), and portions of a power piston (not shown). When safety valve 100 is deployed within a failed tubing-retrievable safety-valve (not shown) and hydraulically actuated (not shown), production fluids flow in an annulus between the production tubing (not shown) and safety valve 100, enter a central lumen (not shown) of safety valve 100 via the plurality of flow ports 137, and are communicated to the surface through a central lumen (not shown) of the failed tubing-retrievable safety valve (not shown). Safety valve 100 may include a hydraulic chamber housing 146 having a top side attached to a bottom distal end of seat housing 136 and a bottom side attached to a top side of a spring housing 154. Hydraulic chamber housing 146 facilitates hydraulic actuation of safety valve 100 as discussed in more detail herein. Spring housing 154 houses a power spring (not shown) that is disposed below the closure device (not shown) of safety valve 100. Safety valve 100 may also include a nose housing 166 having a top distal end attached to a bottom distal end of spring housing 154 and a bottom distal end having a chamfered shape to facilitate insertion. Continuing,
Upper power piston 150 may be partially disposed within hydraulic chamber housing 146 having a top distal end that is secured to closure device 128 by retaining nut 124. Upper power seal stack 140 and lower power seal stack 152 may be disposed about upper power piston 150 and configured to facilitate hydraulic actuation (not shown) as discussed in more detail herein. Safety valve 100 may include a spring housing 154, a plurality of set screws 156, a lower power piston 158, a bushing 160, a spring ring 162, a power spring 164, a nose housing 166, and a nose plug 168. Power spring 164 may be disposed below the closure device 128, ball 128a in the depicted embodiment, such that the energy stored to close safety valve 100 is disposed below the closure device itself. One of ordinary skill in the art will recognize that one or more of the above-noted components may be added, subtracted, combined, or otherwise modified from what is depicted in the figure in accordance with one or more embodiments of the present invention. For example, other types or kinds of closure devices 128 may be used in place of ball 128a, including, but not limited to, a poppet (e.g., 128b) or other cone-ended cylinder and seat (not shown). However, in all such embodiments, the energy used to close the closure device 128 shall be disposed below the closure device 128.
In certain embodiments, the power piston may include an upper power piston 150 and lower power piston 158 that may be attached to one another to facilitate assembly of valve 100. In other embodiments, the power piston may include a unibody member that may be, for example, simply the combination of upper power piston 150 and lower power piston 158 in a unibody embodiment. For the purposes of this disclosure, reference to an upper power piston 150, lower power piston 158, or power piston may refer to either multi-part or unibody power piston embodiments and reference to upper power piston 150 and lower power piston 158 apply in the same manner to unibody power piston embodiments that is simply a combination of upper power piston 150 and lower power piston 158. SpecifOne of ordinary skill in the art will recognize that the size, shape, and configuration of the power piston may vary based on an application or design in accordance with one or more embodiments of the present invention.
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A bottom end of adapter sub 106 may be attached to a top end of a packer housing 112. A lower packing 110 may be disposed about a portion of packing housing 112 below hydraulic actuation port 186, used in conjunction with an upper packing (not shown) disposed above hydraulic actuation port 186, to facilitate communication by opening up the original hydraulic actuation (not shown) path through the failed tubing-retrievable safety valve (not shown). An inner pressure sleeve 118 may be disposed within adapter sub 106, packing housing 112, and seat housing 136. Inner pressure sleeve 118, adapter sub 106, and spacer 102 of safety valve 100 may include a central lumen 192 through which production fluids (not shown) may flow when safety valve 100 is actuated. To actuate safety valve 100, hydraulic actuation fluid (not shown) received from hydraulic actuation port 186 of adapter sub 106 may be conveyed via a hydraulic passage (not independently illustrated) formed between inner pressure sleeve 118 and adapter sub 106, packer housing 112, and seat housing 136 to a hydraulic access port 190 to a differential area 194 formed within a hydraulic chamber housing 146. Safety valve 100 may include a hard seat 122 disposed within seat housing 136 that serves as a backdrop for the closure device 128, e.g., ball 128a in the depicted embodiment, when safety valve 100 is closed. Seat housing 136 may include a plurality of flow ports 137 and may be configured to house a hard seat 122. In certain embodiments, such as the one depicted in the figure, the plurality of flow ports 137 may be conical sections cutout from seat housing 136 having a shape and size configured to interface with the closure device 128, e.g., ball 128a here, but elongated such that the closure device 128, e.g., ball 128a, disposed within seat housing 136 may travel. Under hydraulic actuation (not shown), the closure device may be configured to controllably move off hard seat 122 and expose the plurality of flow ports 137 to a central lumen 192 of safety valve 100.
A top end of an upper power piston 150 may be attached to the closure device 128, e.g., ball 128a, and upper power piston 150 may include a shoulder portion 198 disposed within hydraulic chamber housing 146 forming differential area 194 therein. A top end of lower power piston 158 may be attached to a bottom end of upper power piston 150 and at least a portion of lower power piston 158 may be disposed within a central lumen 196 of power spring 164. An upper power seal stack 140 may be disposed within hydraulic chamber housing 146 about upper power piston 150 and above hydraulic access port 190. A lower power seal stack 152 may be disposed within hydraulic chamber housing 146 about upper power piston 150 and below hydraulic access port 190. Under hydraulic actuation (not shown), hydraulic fluid (not shown) in the differential area 194 causes the upper 150 and lower 158 power pistons to compress power spring 164 and move the closure device, e.g., ball 128, off the hard seat 122 exposing the plurality of flow ports 137 to the central lumen 192 of safety valve 100, thereby allowing production fluids (not shown) to flow to the surface (not shown). When hydraulic actuation (not shown) is removed, stored energy in power spring 164, disposed below the closure device 128, e.g., ball 128a, causes the closure device to move back on hard seat 122 and close the plurality of flow ports 137 off from production fluid (not shown) flow.
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Advantages of one or more embodiments of the present invention may include one or more of the following:
In one or more embodiments of the present invention, the energy used to close the closure device of a surface-controlled wireline-retrievable safety valve is stored below the closure device.
In one or more embodiments of the present invention, a surface-controlled wireline-retrievable safety valve provides more robust equalization than a conventional safety valve using a flapper, equalizing dart, or equalizing dart spring design. Advantageously, the hydraulic pressure across the closure device is automatically equalized, reducing the amount of hydraulic actuation pressure required to compress the power spring and open the closure device to expose the plurality of flow ports to production flow through the safety valve.
In one or more embodiments of the present invention, a surface-controlled wireline-retrievable safety valve may be run deeper for the same hydraulic actuation pressure than a conventional safety valve because the energy used to close the closure device of the safety valve is disposed below the closure device and the hydraulic pressure across the closure device is automatically equalized.
In one or more embodiments of the present invention, a surface-controlled wireline-retrievable safety valve provides an increased area for production flow through the safety valve than conventional safety valves including flapper-based safety valves and flow tube safety valves.
In one or more embodiments of the present invention, a surface-controlled wireline-retrievable safety valve reduces manufacturing complexity compared to that of conventional safety valves.
In one or more embodiments of the present invention, a surface-controlled wireline-retrievable safety valve provides extended service life compared to that of conventional safety valves because of its robust design that increases longevity.
While the present invention has been described with respect to the above-noted embodiments, those skilled in the art, having the benefit of this disclosure, will recognize that other embodiments may be devised that are within the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the appended claims.
This application claims the benefit of, or priority to, U.S. Provisional Patent Application Ser. No. 62/779,121, filed on Dec. 13, 2018, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62779121 | Dec 2018 | US |
