GB2172321A - High temperature subsurface safety valve - Google Patents

Abstract

A subsurface safety valve for controlling the fluid flow through a well conduit having an improved fluid actuator with a ceramic piston 40 connected to and actuating the valve and movable in a cylinder 48 having a cylinder sleeve 50. The cylinder includes metal valve seats 60 and metal valve elements 64 are connected to the piston for seating on the valve seats for providing positive seals. <IMAGE>

Description

SPECIFICATION High temperaturesubsurfacesafety valve In producing oil from wells, it has become important to provide a safety valve for use in high temperature environments. For example, in orderto increase recovery, it is conventional to inject steam into a well to heat and thin the oil for increasing recovery.

However, high temperatures are involved, such as 800" F (426.66 C). Generally, an ail metal safety valve such as disclosed in GB 2 148 979B would be sufficient with the exception ofthe lubricants necessary to operate the piston actuating means. Most lubricating fluids will not exist in a liquid state at extremely high temperatures to provide the desired lubricity needed forthe metal piston and cylinder assembly.

The present invention is directed to a subsurface safety valve having a fluid actuator using a ceramic piston movable in a cylinder having a ceramic interior.

A ceramic piston and cylinder need not provide a positive seal, but only resistance to fluid flow sufficientto actuatethe safety valve. However, the ceramic piston and cylinder will withstand the extremely high temperatures without lubricants. In orderto provide positive sealing,the cylinder includes two spaced metal valve seats and the piston includes two metal valve elements for sealing the ceramic piston and cylinder assembly at opposite ends oftravel.

The present invention provides a subsurface well safety valve for controlling fluid flow through a well conduit which includes a housing and a valve closure member moving between open and closed positoins for controlling the fluid flowthrough the bore, a flow tube telescopically movable in the housing for con- trolling the movement of the valve closure member and biasing means are provided for moving the flow tube in a direction to close the valve, a cylinder in the housing, which cylinder includes a ceramic interior, a ceramic piston movable in the ceramic interior of the cylinder in response to fluid acting in the cylinder, the piston being connected to and moving the flow tu be;; the cylinder on one side of the piston is adapted to be in communication with a fluid control passageway and the cylinder on the second side of the piston is adapted to be in communication with a biasing fluid; the cylinder includes first and second spaced metal valve seats and first and second metal valve elements are connected tothe piston,thefirst and second elements being spaced from each other to alternately seat and unseat on the first and second valve seats, respectively, as the piston alternately moves in the cylinder.

Preferably, the piston includes a labyrinth seal providedforexamplebya plurality of circular grooves on the piston. The ceramic interior of the cylinder may be a sleeve positioned between and spaced from the metal valve seats.

Other andfurtherfeatures and advantages will be apparent from the following description of a presently preferred embodiment of the invention, given for the purpose of disclosure and taken in conjunction with the accompanying drawings in which Fig. 7A and 1 B are continuations of each other and comprise an elevational view, in quarter section, of a well safety valve utilizing the present invention and shown into open position, Fig. 2 is a cross-sectional viewtaken along the line 2-2 of Fig. 1 B, and Fig. 3 is an enlarged fragmentary cross-sectional view of the fluid actuating means.

While the present invention will be described in connection with a subsurface tubing safety valve having a flappertype closure member, for purpose of illustration only, it is understood thatthe present invention may be used with other types of safety valves and other valve closure members.

Referring now to the drawings, and particularly to Figs. 1A and 1 B, the reference numeral 10 generally indicates a subsurface tubing safetyvalve ofthe present invention which includes a body or housing 12 which is adapted to be connected in a well tubing to permit well production therethrough under normal operating conditions, but in which the safetyvalve may close or be closed in response to abnormal conditions.

Thevalve 10includesa bore 14,an annularvalve seat 16 positioned about the bore 14, a valve closure element such as aflappervalve 18 connected to the body 12 bya pivot pin 20. Thus, when theflappervalve 18 is in the upward position and seated on the valve seat 16, the safety valve 10 is closed blocking flow upwardly through the bore 14 and well tubing.

A longitudinal tubular member orflowtube 22 is telescopically movable in the body 12 and through the valve seat 16. As best seen in Fig. 1 B, when the flow tube 22 is moved to a downward position,the tube 22 pushes the flapper 18 away from the valve seat 16.

Thus the valve is heid in the open position so long as the tube 22 is in the downward position. When the tube 22 is moved upwardly, the flapper 18 is allowed to move upwardly onto the seat 16 bythe action of a spring 24.

Theflowtube22 is biased upwardly in an upward direction by any suitable means which may include a spring 26 foryieldably urging theflowtube 22 in an upward direction to release the fla pper 18 for closing the vlave 10. The safety valve 10 is controlled bythe applicable or removal of a pressurized fluid, such as steam, through a control path or line, such as one or more control lines 32 extending to the well surface or through the casing annulus, which supplies pressurized steam to the top of one or more pistons 40 which are connected to the flow tube 22 by a tongue and groove connection 42 for moving theflowtube 22 downwardly forcing the flapper 18 off of the seat 16 and into the full open position. The safety valve 10is controlled by the application or removal of pressurized fluid through the control line 32 and a fluid passageway 46 to supply pressurized fluid to a cylinder48 and the top of the piston 40. The bottom of the piston 40 is exposed to fluid pressure in the bore 14, or in the case of other types of safety valves, to annulusfluid, which acts against the bottom ofthe piston 40for biasing theflowtube 22 to the closed position when thefluid control pressure is removed fromthecontrol line The above description is generally as in GB 2148 979B which utilizes a metal piston.While such aforesaid all metal safety valve is a great improvement over pistons using elastomer seals and can be used in hostile and high temperature environments, the prior art of a metal piston and cylinder required lubricants.

However, lubricants at the extremely high temperatures utilized in steam injection wells, for example 800" F (426.66 C), do not exist in a liquid state. The present invention is directed to a piston 40 made of a suitable ceramic which operates in a cylinder48 having a ceramic interior such as a ceramic sleeve 50.

A suitable ceramic is Type K-6 sold by Coors Ceramics.

The ceramic piston 40 and the ceramic sleeve 50 have sufficient lubricitythatthey can withstand the extremely high temperatures encountered in steam injection wells. In order to operate, the piston 40 need not provide a positive seal in the cylinder48 but need only provide a minimum leakage seal that offers resistance to fluid flow while providing clearance.

Preferably, the piston 40 may be of a labyrinth seal such as plurality of circumferential grooves 52 which have a minimum of sealing action. The fact, the piston 40 could be merely a smooth elongated rod of ceramic material with a sufficiently close fit in the cylinder48 whereby the pressure drop acting across the piston would be sufficient to move the flowtube 22.

However, since the ceramic piston 40 and sleeve 50 are provided with some leakage, it is desirable to provide positive valve element seals which will provide a positive seal in both directionsforthe double acting piston 40.

Referring now to Fig. 1A and 3, the cylinder 48 includes a first metal valve seat 60 on one side ofthe piston 40 and in communication with the fluid control passagway 46 whereby pressurized control fluid can flow to and actuate the top ofthe piston 40 through the valve seat 60.A second metal valve seat 62 (Fig. 1A) is provided on the cylinder 48 on the second side of the piston 40 through which biasing fluid pressure, such as in the bore 14, canflowtothe bottom side of and actuate the piston 40. Afirst metal valve element 64 is provided connected to the first side of the piston 40 and is adapted to seat on the first valve seat 60to provide a positive seal when the piston 40 moves away from the valve seat 60 (Fig. 1A and 3). A second metal valve element66 (Fig. 1B)isadaptedtoseaton the second valve seat 62 and provide a positive seal when the piston 40 moves away from the second valve seat 62.Preferably, the valve element 64 is connected to the piston 40 by a ball 68 and socket 70 universal connection for allowing the piston 40 to align itself properly in the cylinder48 without binding.

Therefore, the piston 40 merely provides a dynamic seal in the piston 48 sufficientto cause movement of the piston 40 in the cylinder48 to actuate the flowtube 22. The valve elements 64 and 66 provide static and positive seals when they are seated on their respective valve seats 60 and 62. Therefore, with the use of the positive valve element 64 and 66, leakage of fluids past the piston 40 will not cause the fluid actuating system to become inoperative so long as the piston 40 seals sufficiently in the cylinder 48to move the valve element64and66totheirseatedpositions. Oncethe valve elements 64 and 66 are in the seated position, fluid pressure acting on the backside ofthe elements 64 and 66 will positively seat and keep the valve elements 64 and 66 seated.

In operation, when pressurized control fluid such as steam, is supplied to the line 32, fluid will flow into the passageway 46 and into the cylinde,-48 above the piston 40 moving the piston 40 downwardly which in turn carries the flow tube 22 downwardly to open the flapper 18. Downward movement ofthe piston 40 carriesthe valve element 64 downwardly until it contacts and seats on the valve seat 60 to provide a positive seal and furtherfluid pressure in the fluid passageway46 acts on the back of the valve element 64to hold it in the sealed position. When it is desired to close the valve, pressure in the fluid control line 32 is reducedthereby reducing the pressure in the passageway 46 and on top of the valve element 54.The biasing fluid pressure in the bore 14 ofthe safety valve 10 or in the casing annulus (not shown) is in communication with the cylinder48 and the bottom ofthe piston 40 and along with the spring 26 biases the piston 40 in an upward direction until the valve element 66 is seated on the valve seat 62to provide a positive seal in the upward direction. Thereafter, the biasing fluid pressure acks on the back of the valve element 66 along with the action of spring 26 to maintain the element 66 in a sealed position on the valve seat 62.

CLAl\iS 1. In a subsurface well safety valve for controlling ehsfluidflowthrough awell conduit and including a housing having a bore and a valve closure member moving between open and closed positions for controllinq the fluid flow through the bore, a flowtube lescopicaliymoving in the housing for controlling the movement of the valve closure member, and biasing means for moving the flow tube in a direction do close the valve, the improvement in fluid actuating rneansforactuating theflowtube comprising, a cylinder in the housing, said cylinder including a ceramic interior, a ceramic piston movable in the ceramic interior of the cylinder in response to fluid acting in the cylinder, said piston connected to and movingtheflowtube, said cylinder on one side ofthe piston adapted to be in communication with a fluid control passageway, and said cylinder on the second side of the piston adapted to be in comrrau communication with a biasing fluid, said cylinder including first and second spaced metal valve seats, and first and second metal valve elements connected to the piston, said first and second elements spaced from each other to alternately seat and unseat on the first and second valve seats, respectively, as the piston alternately moves in the cylinder.

2. A valve as claimed in Claim 1 wherein the piston includes a labyrinth seal.

3. A valve as claimed in Claim 1 wherein the piston includes a plurality of circular grooves.

4. A valve as claimed in Claim 1 wherein the ceramic interior of the cylinder is a sleeve positioned between and spaced from said metal seats.

5. Asafetyvalve substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. over pistons using elastomer seals and can be used in hostile and high temperature environments, the prior art of a metal piston and cylinder required lubricants. However, lubricants at the extremely high temperatures utilized in steam injection wells, for example 800" F (426.66 C), do not exist in a liquid state. The present invention is directed to a piston 40 made of a suitable ceramic which operates in a cylinder48 having a ceramic interior such as a ceramic sleeve 50. A suitable ceramic is Type K-6 sold by Coors Ceramics. The ceramic piston 40 and the ceramic sleeve 50 have sufficient lubricitythatthey can withstand the extremely high temperatures encountered in steam injection wells. In order to operate, the piston 40 need not provide a positive seal in the cylinder48 but need only provide a minimum leakage seal that offers resistance to fluid flow while providing clearance. Preferably, the piston 40 may be of a labyrinth seal such as plurality of circumferential grooves 52 which have a minimum of sealing action. The fact, the piston 40 could be merely a smooth elongated rod of ceramic material with a sufficiently close fit in the cylinder48 whereby the pressure drop acting across the piston would be sufficient to move the flowtube 22. However, since the ceramic piston 40 and sleeve 50 are provided with some leakage, it is desirable to provide positive valve element seals which will provide a positive seal in both directionsforthe double acting piston 40. Referring now to Fig. 1A and 3, the cylinder 48 includes a first metal valve seat 60 on one side ofthe piston 40 and in communication with the fluid control passagway 46 whereby pressurized control fluid can flow to and actuate the top ofthe piston 40 through the valve seat 60.A second metal valve seat 62 (Fig. 1A) is provided on the cylinder 48 on the second side of the piston 40 through which biasing fluid pressure, such as in the bore 14, canflowtothe bottom side of and actuate the piston 40. Afirst metal valve element 64 is provided connected to the first side of the piston 40 and is adapted to seat on the first valve seat 60to provide a positive seal when the piston 40 moves away from the valve seat 60 (Fig. 1A and 3). A second metal valve element66 (Fig. 1B)isadaptedtoseaton the second valve seat 62 and provide a positive seal when the piston 40 moves away from the second valve seat 62.Preferably, the valve element 64 is connected to the piston 40 by a ball 68 and socket 70 universal connection for allowing the piston 40 to align itself properly in the cylinder48 without binding. Therefore, the piston 40 merely provides a dynamic seal in the piston 48 sufficientto cause movement of the piston 40 in the cylinder48 to actuate the flowtube 22. The valve elements 64 and 66 provide static and positive seals when they are seated on their respective valve seats 60 and 62. Therefore, with the use of the positive valve element 64 and 66, leakage of fluids past the piston 40 will not cause the fluid actuating system to become inoperative so long as the piston 40 seals sufficiently in the cylinder 48to move the valve element64and66totheirseatedpositions. Oncethe valve elements 64 and 66 are in the seated position, fluid pressure acting on the backside ofthe elements 64 and 66 will positively seat and keep the valve elements 64 and 66 seated. In operation, when pressurized control fluid such as steam, is supplied to the line 32, fluid will flow into the passageway 46 and into the cylinde,-48 above the piston 40 moving the piston 40 downwardly which in turn carries the flow tube 22 downwardly to open the flapper 18. Downward movement ofthe piston 40 carriesthe valve element 64 downwardly until it contacts and seats on the valve seat 60 to provide a positive seal and furtherfluid pressure in the fluid passageway46 acts on the back of the valve element 64to hold it in the sealed position. When it is desired to close the valve, pressure in the fluid control line 32 is reducedthereby reducing the pressure in the passageway 46 and on top of the valve element 54.The biasing fluid pressure in the bore 14 ofthe safety valve 10 or in the casing annulus (not shown) is in communication with the cylinder48 and the bottom ofthe piston 40 and along with the spring 26 biases the piston 40 in an upward direction until the valve element 66 is seated on the valve seat 62to provide a positive seal in the upward direction. Thereafter, the biasing fluid pressure acks on the back of the valve element 66 along with the action of spring 26 to maintain the element 66 in a sealed position on the valve seat 62. CLAl\iS

1. In a subsurface well safety valve for controlling ehsfluidflowthrough awell conduit and including a housing having a bore and a valve closure member moving between open and closed positions for controllinq the fluid flow through the bore, a flowtube lescopicaliymoving in the housing for controlling the movement of the valve closure member, and biasing means for moving the flow tube in a direction do close the valve, the improvement in fluid actuating rneansforactuating theflowtube comprising, a cylinder in the housing, said cylinder including a ceramic interior, a ceramic piston movable in the ceramic interior of the cylinder in response to fluid acting in the cylinder, said piston connected to and movingtheflowtube, said cylinder on one side ofthe piston adapted to be in communication with a fluid control passageway, and said cylinder on the second side of the piston adapted to be in comrrau communication with a biasing fluid, said cylinder including first and second spaced metal valve seats, and first and second metal valve elements connected to the piston, said first and second elements spaced from each other to alternately seat and unseat on the first and second valve seats, respectively, as the piston alternately moves in the cylinder.

2. A valve as claimed in Claim 1 wherein the piston includes a labyrinth seal.

3. A valve as claimed in Claim 1 wherein the piston includes a plurality of circular grooves.

4. A valve as claimed in Claim 1 wherein the ceramic interior of the cylinder is a sleeve positioned between and spaced from said metal seats.

5. Asafetyvalve substantially as hereinbefore described with reference to the accompanying drawings.