SURFACE CONTROLLED SUBSURFACE SAFETY VALVE
A safety valve for subsurface disposal equipped with an interfacing element of elastomeric and non-elastomeric components. The components include an elastomeric energizing component and a non-elastomeric seal ring configured to work together in attaining an internal seal sufficient for allowing the valve to remain consistently closed. Indeed, the aid afforded by the interfacing element may allow the valve to remain consistently and effectively closed even in particularly low pressure well environments or those of widely varying temperatures.
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This Patent Document claims priority under 35 U.S.C. §119 to U.S. Provisional App. Ser. No. 61/526,067, filed on Aug. 22, 2011, and entitled, “Low Gas Migration System for Surface Controlled Subsurface Safety Valve”, incorporated herein by reference in its entirety.
BACKGROUNDExploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. In recognition of these expenses, added emphasis has been placed on efficiencies associated with well completions and maintenance over the life of the well. Over the years, ever increasing well depths and sophisticated architecture have made reductions in time and effort spent in completions and maintenance operations of even greater focus. Similarly, increased safeguards in terms of hardware design may help minimize expenditures when operational interruptions do occur.
In terms of overall architecture and hardware, the well may be outfitted with a ‘tree’ of pressure regulating equipment and conventional well head at the oilfield surface. Additionally, safety valves, packers and other hardware may be incorporated into well tubular architecture as a manner by which to help regulate or manage subsurface fluid activity. For example, a surface controlled subsurface safety valve may be incorporated into the well tubular immediately below the well head. Thus, as described further below, safeguard may be provided for closing off well production, such as in the event of a loss of well control.
A surface controlled subsurface safety valve is a valve through which all fluids pass which are obtained from the well. That is, the production tubular extending below the well head and providing all of the access to the well may include this safety valve so as to allow production to be shut off when this valve is closed. For example, this may occur when the operator at the oilfield surface is alerted to a hazardous condition which may require the halting of production. However, the safety valve may be even more beneficial in circumstances where an automatic shut-off is required in the face of an unexpected loss of well control or other sudden, potentially hazardous event.
In order to achieve immediate, or near immediate, shut-off for circumstances as noted above, the valve is configured in a manner to be ‘normally closed’, for example, in the absence of positive hydraulic pressure directed thereat. Thus, should a sudden event emerge at the well head or nearby, the resulting loss of hydraulic pressure or other actuating force at the valve would result in its closure. As a result, production may be sealed off and terminated at a point below the well head until such time as it may safely be restored. That is, once issues at the well head or other potentially impaired surface control equipment have been adequately addressed.
Effective use of a surface controlled subsurface safety valve as indicated depends on both surface conditions and subsurface conditions. For example, as noted above, the surface conditions of well or operator control may lead to valve closure. However, effectively achieving a full seal with the valve is also aided in part based on subsurface conditions. So, for example, where the valve is of a flapper configuration, its completed closure is aided by the pressure of the well at a point below the valve. Indeed, pressure of over about 50-75 PSI from a point below the flapper is generally sufficient to ensure an effective seal of the valve and a complete halt to fluid production.
Unfortunately, in many circumstances, the pressure in the well is well below the above noted range and may be largely negligible altogether. When this is the case, the flapper may fail to achieve full closure due the lack of additional pressure support from the well. As a result, a slow, but nevertheless hazardous, migrating leakage of gaseous production fluid is often the case. That is, even where an attempted shut-off takes place due to a surface related emergency, hazardous production may continue to spill out from the well.
The reason for the lack of complete valve closure without the added aid of well pressure relates to the manner in which the closure takes place. That is, presently, a hydraulic piston is utilized such that positive hydraulic pressure is translated into a spring compression that that opens the valve. Thus, in theory, when the hydraulic pressure is removed as directed by surface conditions, the spring is allowed to expand and result in valve closure.
Unfortunately, without the aid of higher pressure from below the valve, the flapper is not assured to maintain an uninterrupted seal. Thus, as a practical matter, the corresponding failure of the adjacent hydraulic piston will allow for the migration of fluids uphole past the entire valve assembly. In sum, conventional surface controlled subsurface safety valves are often ineffective safeguards when utilized in conjunction with particularly low pressure wells.
SUMMARYA surface controlled subsurface safety valve is disclosed having a valve housing coupled to a hydraulic line for running to an oilfield surface. The housing is coupled to the line at a valve seat thereof. A valve element disposed in the housing is configured for closing at an interface of the seat. The element includes an elastomeric energizing component adjacent a non-elastomeric seal ring for meeting the interface upon the valve closure. Of course, this summary is provided to introduce a selection of concepts that are further described below and is not intended as an aid in limiting the scope of the claimed subject matter.
Embodiments are described with reference to certain valve positioning in particular oilfield environments. For example, embodiments depicted herein reveal a valve assembly for incorporation immediately below a well head of conventional land based equipment. However, embodiments of safety valves as detailed herein may be suitable for offshore operations or further subsurface positioning. Regardless, the valve is outfitted with an element that includes an energized portion in conjunction with a non-elastomeric ring. Thus, not only is the valve configured for achieving effective sealable closure in low pressure well environments, it is also well suited for repeated use without undue concern over damage and premature failure.
Referring now to
Setting the valve 190 to an open or closed position is determined by an internal spring 185, or other suitably responsive element, located adjacent the valve 190. In the embodiment of
Continuing with reference to
As detailed hereinbelow, the piston 125 is outfitted with an interfacing element 100 configured to durably achieve sealed closure as the piston 125 interfaces the seat 122. Thus, reliable sealed closure of the valve 190 therebelow may be achieved when positive pressure is removed from the line 120 above the piston 125. Once more, the interfacing of the piston 125 and seat 122 may be achieved without undue damage or resulting wear to the element 100. Therefore, repeated reliable closure of the valve 190 may be expected over a more extended period of use.
Referring now to
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With particular reference to
Once more, the intact seal between the ring 200 and seat 122 is achieved in a manner that avoids undue wear on the underlying component 300. That is to say, rather than utilize the component 300 to provide seal capacity in addition to the described biasing and energizing effect noted above, a durable intervening seal ring 200 is provided. As a result not only is the seal maintained but the element 100, and indeed the entire assembly 101, may be repeatedly used without requiring change-out and/or component 300 replacement every few times the valve 190 is closed (see
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With added reference to
Referring specifically now to
A host of oilfield equipment 520 is disposed at the oilfield surface 500. In the embodiment shown, this includes pressure regulating equipment 525, an operator control unit 522 and a well head 527 from which the noted production tubing 581 is deployed. A production line 529 is also shown emerging from the well head 527 for transport of produced fluids. Additionally, a rig 521 is depicted which may support a host of different types of interventional applications over the life of the well 580.
Continuing with reference to
Referring now to
Once production is to be halted, the valve assembly may be closed based on surface conditions. That is, whether through operator direction (660) or as a result of an emergent well control issue (675), the assembly may be closed so as to safely halt production. In fact, even in circumstances of low well pressure or widely varying downhole temperatures, maintaining of the closure may be reliably assured. As indicated at 690 this is due to the aid of a durably energized valve element of the assembly.
Embodiments described hereinabove include a subsurface safety valve configured to achieve effective sealable closure. This remains the case even in the face of particularly low pressure well environments which lack any significant valve closure aid in the form of downhole pressure. Once more, this may be achieved in a robust and repeatable manner without undue concern over premature valve failure due to degrading energizing valve components.
The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. Regardless, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.
Claims
1. A surface controlled subsurface safety valve assembly comprising:
- a hydraulic line running from an oilfield surface;
- a valve housing coupled to said line at a valve seat thereof; and
- an interfacing element disposed in said housing for closing upon the seat and having an energizing component adjacent a non-elastomeric seal ring for meeting the seat upon the closing.
2. The valve assembly of claim 1 wherein the seal ring is of a material selected from a group consisting of copper, brass and polytetrafluoroethylene.
3. The valve assembly of claim 1 wherein the energizing component is selected from a group consisting of a spring and an elastomeric material.
4. The valve assembly of claim 3 wherein the elastomeric material is selected from a group consisting of rubber and polyether ether ketone.
5. The valve assembly of claim 1 further comprising:
- a central channel disposed in said housing for guiding fluid from a location below the assembly to a location above the assembly; and
- a valve disposed in said channel for regulating the guiding.
6. The valve assembly of claim 5 wherein said valve is a flapper valve.
7. The valve assembly of claim 5 wherein said interfacing element is disposed at an end of a hydraulic piston located in said line for coupling to said valve.
8. The valve assembly of claim 7 wherein the coupling is provided by a responsive element disposed between said piston and said valve.
9. The valve assembly of claim 8 wherein the responsive element is a spring for compressibly opening said valve in response to movement of said hydraulic piston in said line.
10. A fluid control system for use at an oilfield, the system comprising:
- well control equipment disposed at a surface of the oilfield;
- a tubular disposed in a well at the oilfield and coupled to said equipment; and
- a safety valve disposed in said tubular and having an element with energizing and non-elastomeric components for substantially maintaining a sealed interface at a seat of said valve during closure thereof.
11. The system of claim 10 wherein said valve is rated to substantially maintain the closure at well pressure below about 50 PSI.
12. The system of claim 10 wherein said valve is rated to substantially maintain the closure at well temperatures of between about 40° F. and about 350° F.
13. The valve of claim 10 wherein said tubular is a production tubular.
14. The valve of claim 13 wherein said equipment is a well head, said safety valve disposed subsurface within said production tubular adjacent said surface disposed well head.
15. A method of regulating subsurface fluid flow in a well from a surface location adjacent the well, the method comprising:
- closing a safety valve in the well to prevent fluid flow therethrough, said closing including allowing sealing of an internal piston of the valve at a valve seat of the valve; and
- substantially maintaining said closing by way of an interfacing element of the piston having an energizing component adjacent a non-elastomeric seal ring, the ring to meet the seat for the sealing.
16. The method of claim 15 further comprising directing an opening of the valve from the surface location prior to said closing.
17. The method of claim 16 wherein said directing comprises maintaining hydraulic pressure on the piston throughout a duration of the opening.
18. The method of claim 15 wherein the sealing is powered by a spring coupled to the piston and configured to responsively expand during the allowing.
19. The method of claim 15 further comprising directing said closing from a control unit positioned at the surface location.
20. The method of claim 15 wherein said closing is automatic in response to an emergent condition of equipment positioned at the surface location and in fluid communication with the safety valve.
Type: Application
Filed: May 2, 2012
Publication Date: Feb 28, 2013
Applicant: SCHLUMBERGER TECHNOLOGY CORPORATION (Sugar Land, TX)
Inventors: Emrah Gokdag (Houston, TX), Mark Anderson (Pearland, TX), Paul Jeffery Johantges (Deer Park, TX), Jason A. McCann (Houston, TX)
Application Number: 13/462,695
International Classification: E21B 34/16 (20060101); E21B 34/06 (20060101); E21B 34/00 (20060101);