Equalizing subsurface safety valve with injection system

EQUALIZING SUBSURFACE SAFETY VALVE WITH INJECTION SYSTEM

RELATED APPLICATIONS

0003This application claims the benefit of U. S. Provisional Application No. 60/062,297, filed October 17, 1997.

0004BACKGROUND OF THE INVENTION 1. Field Of The Invention

0005The present invention relates to a subsurface safety valve used for controlling fluid flow in a well conduit and, more particul.arly, to a pressure equalizing subsurface safety valve having a fluid injection system.

00062. Description Of The Related Art

0007Subsurface safety valves are commonly used in wells to prevent uncontrolled fluid flow through the well in the event of .an emergency, such as to prevent a well blowout. Conventional

0008safety valves use a flapper which is biased by a spring to a normally closed position, but is retained in an open position by the application of hydraulic fluid from the earth^'s surface. A

0009typical subsurface safety valve is shown and described in U.S. Pat. No. 4.161.219. which is

0010commonly assigned hereto.

0011One problem associated with subsurface safety valves relates to the corrosive effect of

0012well fluids on the material from which subsurface safety valves have been made. One solution to this problem is to make the safety valve from materials that are resistant to such corrosion.

0013The drawback to this solution is that, due to the greater expense of noble metals, the cost of the

0014safety valve is much greater than before. An alternative to making the safety valve from these costlier materials is to inject various chemicals into the safety valve. The chemicals mix with the production fluid and protect the safety valve. The injection fluids may be chemicals such as for retarding corrosion, scale, parafin, asphaltenes, and the like. It is therefore an object of the

0015present invention to provide an improved subsurface safety valve having a means for injecting fluids into the safety valve.

0016Another problem associated with subsurface safety valves may arise when moving the valve closure member from its closed to its open position. When the closure member is in the

0017closed position, well fluid pressure below the closure member acting upon a relatively large

0018surface area of the closure member makes opening of the closure member difficult. This

0019difficulty in opening cannot be easily overcome simply by increasing the force exerted against the closure member by an opening piston and cylinder assembly because the relatively small cross-sectional area of the opening piston and cylinder assembly would require a fluid pressure that may burst the control line carrying hydraulic fluid from the earth^'s surface to the piston and

0020cylinder assembly. Additionally, when the closure member is opened the initial flow of well

0021fluid is relatively rapid which tends to etch, or erode, the primary sealing surface of the closure member. Any damage to this primary sealing surface is extremely critical because it is this

0022sealing surface which must be intact to prevent uncontrolled flow of well fluids. The present

0023invention solves these difficulties by providing a subsurface safety valve with an equalizing

0024mechanism to allow the pressure above and below the closure member to equalize prior to the

0025complete opening of the closure member.

SUMMARY OF THE INVENTION

0027The present invention has been contemplated to overcome the foregoing deficiencies and meet the above described needs. In a broad aspect, the invention may be a subsurface safety

0028valve for controlling fluid flow in a well conduit including: a body member having a longitudinal

0029bore extending therethrough; a valve actuator disposed for axial movement within the

0030longitudinal bore; means for controllably moving the valve actuator within the longitudinal bore; a closure member mounted within the body member to control fluid flow through the

0031longitudinal bore: means for biasing the closure member to a normally closed position to prevent

0032fluid flow through the longitudinal bore: means for biasing the valve actuator away from the

0033closure member: and. a fluid flowpath disposed within the body member, the flowpath being in fluid communication with the longitudinal bore and a source of injection fluid. Another feature

0034of this aspect of the invention is that a fluid injection conduit may controllably connect the fluid flowpath to the source of injection fluid. Another feature of this aspect of the invention is that the valve may further include an annular fluid passageway disposed within the body member and

0035in fluid communication with the fluid flowpath. and a plurality of fluid injection ports in fluid

0036communication with the annular fluid passageway and the longitudinal bore. Another feature of

0037this aspect of the invention is that the plurality of fluid injection ports may extend radially inwardly from the annular fluid passageway to the longitudinal bore. Another feature of this

0038aspect of the invention is that the plurality of fluid injection ports may be substantially evenly

0039spaced about the periphery of the longitudinal bore. Another feature of this aspect of the

0040invention is that the valve may further include at least one backflow prevention device for preventing backflow of injection fluids from the fluid flowpath into the source of injection fluid. Another feature of this aspect of the invention is that the at least one backflow prevention device

0041may be a one-way check valve. Another feature of this aspect of the invention is that the valve may further include a first backflow prevention device and a second backflow prevention device, the first and second backflow prevention devices being disposed in series relationship with the

0042fluid flowpath and a fluid injection conduit connected to the source of injection fluid. Another

0043feature of this aspect of the invention is that the first and second backflow prevention devices

0044may be one-way check valves. Another feature of this aspect of the invention is that the valve may further include at least one testing device connected to the fluid injection conduit for

0045checking the integrity of the fluid injection conduit. Another feature of this aspect of the

0046invention is that the testing device may include a housing having a rupturable member disposed

0047therein. Another feature of this aspect of the invention is that the rupturable member may be a rupture disc. Another feature of this aspect of the invention is that the testing device may include a housing having a rupturable lip, and a plug for sealably mating with an aperture formed by the

0048rupturable lip. Another feature of this aspect of the invention is that the housing of the testing

0049device may further include at least one control conduit extension having at least one flow port.

0050In another aspect, the invention may be a subsurface safety valve for controlling fluid flow in a well conduit including: a body member having a longitudinal bore extending

0051therethrough; a valve actuator disposed for .axial movement within the longitudinal bore: means

0052for controllably moving the valve actuator within the longitudinal bore; a closure member

0053mounted within the body member to control fluid flow through the longitudinal bore; means for

0054biasing the closure member to a normally closed position to prevent fluid flow through the longitudinal bore; means for biasing the valve actuator a ay from the closure member; a fluid injection conduit connecting a source of injection fluid to the body member; a fluid flowpath

0055disposed within the body member and in fluid communication with the fluid injection conduit;

0056and a lockout sleeve disposed within the longitudinal bore, the lockout sleeve having an inner

0057bore for receiving a first end of the valve actuator, and a fluid passageway in fluid communication with the fluid flowpath and the inner bore. Another feature of this aspect of the invention is that the fluid injection conduit may be controllably connected to a source of injection

0058fluid located at the earth's surface. Another feature of this aspect of the invention is that the fluid

0059passageway in the lockout sleeve may include an annular fluid passageway and a plurality of fluid injection ports, the annular fluid passageway being in fluid communication with the fluid

0060flowpath. and the plurality of fluid injection ports being in fluid communication with the annular

0061fluid passageway and the inner bore. Another feature of this aspect of the invention is that the

0062plurality of fluid injection ports may extend radially inwardly from the annular fluid passageway

0063to the inner bore. Another feature of this aspect of the invention is that the plurality of fluid injection ports may be substantially evenly spaced about a periphery of the inner bore. Another

0064feature of this aspect of the invention is that the lockout sleeve may include a shoulder having a first face, the fluid passageway being disposed in the first face, the safety valve further including means for sealing the fluid passageway. Another feature of this aspect of the invention

0065is that the sealing means may include a sealing ring disposed adjacent the first face, and a retainer ring for securing the sealing ring to the first face. Another feature of this aspect of the invention

0066is that the sealing ring may be made of Teflon. Another feature of this aspect of the invention

0067is that the plurality of fluid injection ports may extend radially inwardly from the annular fluid

0068passageway to the inner bore. Another feature of this aspect of the invention is that the plurality of fluid injection ports may be substantially evenly spaced about a periphery of the inner bore.

0069Another feature of this aspect of the invention is that the longitudinal bore may include an

0070annuls groove in fluid communication with the fluid flowpath in the body member and the fluid passageway in the lockout sleeve. Another feature of this aspect of the invention is that the fluid passageway in the lockout sleeve may include a plurality of fluid injection ports in fluid

0071communication with the annular groove and the inner bore of the lockout sleeve. Another feature of this aspect of the invention is that the plurality of fluid injection ports may extend radially inwardly from the annular groove to the inner bore. Another feature of this aspect of the

0072invention is that the plurality of fluid injection ports may be substantially evenly spaced about a periphery of the lockout sleeve. Another feature of this aspect of the invention is that the valve

0073may further include at least one backflow prevention device for preventing backflow of injection

0074fluids from the fluid flowpath into the fluid injection conduit. Another feature of this aspect of

0075the invention is that the at least one backflow prevention device may be a one-way check valve. Another feature of this aspect of the invention is that the valve may further include a first

0076backflow prevention device and a second backflow prevention device, the first and second

0077backflow prevention devices being disposed in series relationship with the fluid flowpath and the fluid injection conduit. Another feature of this aspect of the invention is that the first and second

0078backflow prevention devices may be one-way check valves. Another feature of this aspect of the invention is that the valve may further include at least one testing device connected to the fluid

0079injection conduit for checking the integrity of the fluid injection conduit. Another feature of this aspect of the invention is that the testing device may include a housing having a rupturable

0080member disposed therein. Another feature of this aspect of the invention is that the rupturable

0081member may be a rupture disc. Another feature of this aspect of the invention is that the testing

0082device may include a housing having a rupturable lip. and a plug for sealably mating with an

0083aperture formed by the rupturable lip. Another feature of this aspect of the invention is that the

0084housing of the testing device may further include at least one control conduit extension having

0085at least one flow port.

0086In yet another aspect, the invention may be a method of equalizing pressure in a

0087subsurface safety valve, the subsurface safety valve having a body member having a longitudinal

0088bore extending therethrough, a valve actuator disposed for axial movement within the longitudinal bore, means for controllably moving the valve actuator within the longitudinal bore, a closure member mounted within the body member to control fluid flow through the

0089longitudinal bore, means for biasing the closure member to a normally closed position to prevent

0090fluid flow through the longitudinal bore, means for biasing the valve actuator away from the

0091closure member, a fluid injection conduit connecting a source of injection fluid to the body member, and a fluid flowpath disposed within the body member, the flowpath being in fluid communication with the fluid injection conduit and the longitudinal bore, the method comprising

0092the steps of: closing a master valve that controls fluid flow in a well conduit to which the safety

0093valve is connected; and pumping pressurized fluid into the fluid injection conduit, through the fluid flowpath in the body member, and into the longitudinal bore above the closure member until pressure above and below the closure member is equalized. Another feature of this aspect of the invention is that the pressurized fluid being pumped into the longitudinal bore may be

0094contained by a chamber formed within the well conduit above the closure member and below the closed master valve.

0095BRIEF DESCRIPTION OF THE DRAWINGS Figures 1A-1B illustrate a longitudinal cross-sectional view of the present invention.

0096Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1A.

0097Figure 3 is a cross-sectional view taken along line 3-3 of Figure 1A.

0098Figure 4 is a longitudinal cross-sectional view, similar to Figure 1A, showing an

0099alternative specific embodiment of the present invention.

0100Figure 5 is a cross-sectional view of one embodiment of a testing device for testing the

0101integrity of a fluid injection conduit.

0102Figure 6 is a cross-sectional view of another embodiment of a testing device for testing

0103the integrity of the fluid injection conduit.

0104Figure 7 is an exploded view of a portion of the safety valve shown in Figure 1A.

0105Figure 8 is a schematic view of wellbore having a well conduit suspended therein, the

0106well conduit having a safety valve of the present invention connected thereto.

0107Figure 9 is a longitudinal view showing an alternative embodiment of a back flow

0108prevention device .

0109While the invention will be described in connection with the preferred embodiments, it

0110will be understood that it is not intended to limit the invention to those embodiments. On the

0111contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

0113Referring to the drawings in detail, wherein like numerals denote identical elements

0114throughout the several views, there is shown in Figures 1A-1B a specific embodiment of a

0115subsurface safety valve 10 constructed in accordance with the present invention. With reference

0116to Figure 1A, the subsurface safety valve 10 of this specific embodiment is comprised of a

0117generally tubular body member 12 with a longitudinal bore 14 that extends therethrough. Each

0118end of the body 12 includes mechanisms, such as threads 16, for interconnection with a well

0119conduit 68 (Figure 8) suspended within a wellbore 69. Referring to Figure IB, a valve actuator

012018, usually referred to as a flow tube, is disposed within the bore 14 and is adapted for axial

0121movement therein. The flow tube 18 includes a spring 20 disposed therearound that acts upon

0122a shoulder 22 on the flow tube 18 biasing the flow tube 18 away from a closure member 24. The

0123closure member 24 is mounted within the body member 12 to control fluid flow through the

0124longitudinal bore 14.

0125As shown in Figure 1A. in a specific embodiment, a rod-piston system (or other hydraulic

0126operating piston, such as an annular piston) may be provided to controllably move the flow tube

012718 within the longitudinal bore 14. and to open the closure member 24. In a specific

0128embodiment, the rod-piston system may comprise a piston 26 sealably mounted for reciprocal

0129movement within a cylinder 28 located within the wall of the tubular body 12. A first end 30 of

0130the piston 26 is in contact with hydraulic fluid (not shown) provided thereto from the earth^'s

0131surface through a relatively small diameter control conduit 32. A second end 34 of the piston 26

0132is operatively connected, in any suitable manner, to the flow tube 18. When the pressure of

0133hydraulic fluid in the control conduit 32 exceeds the force needed to compress the spring 20. the

0134piston 26 is forced downwardly, thereby causing the flow tube 18 to come into contact with, and open, the closure member 24. In the event that the hydraulic pressure applied to the piston 26

0135is decreased, as by command from the earth's surface or by the control conduit 32 being

0136damaged, the spring 20 forces the flow tube 18 upwardly away from the closure member 24. The

0137closure member 24 is then rotated, and biased, into a closed position by action of a hinge spring

0138(not shown) to a normally closed position to prevent fluid flow into the flow tube 18 and through

0139the longitudinal bore 14.

0140In accordance with a primary objective of the present invention, the subsurface safety

0141valve may also be provided with a system for injecting fluids — such as chemicals for retarding

0142corrosion, scale, parafin, asphaltenes. and the like — into the longitudinal bore 14. Referring to

0143Figure 1A. in a specific embodiment, the system may include a fluid injection conduit 36

0144controllably connecting a source of injection fluid 37 (Figure 8) at the earth^'s surface 66 to the

0145body member 12; a fluid flowpath 38 disposed within the body member 12 and in fluid

0146communication with the fluid injection conduit 36; and a lockout sleeve 40 disposed within the

0147longitudinal bore 14. The lockout sleeve 40 may be provided with an inner bore 42 for receiving

0148a first end 44 of the valve actuator 18. and a fluid passageway in fluid communication with the

0149fluid flowpath 38 and the longitudinal bore 14. As best shown in Figure 2. in a specific

0150embodiment, the fluid passageway may include an annular fluid passageway 46 and a plurality

0151of fluid injection ports 48. The annular fluid passageway 46 is in fluid communication with the

0152fluid flowpath 38, and the plurality of fluid injection ports 48 are in fluid communication with

0153the annular fluid passageway 46 and the inner bore 42. In a specific embodiment, the plurality

0154of fluid injection ports 48 may extend radially inwardly from the annular fluid passageway 46

0155to the inner bore 42. and may be substantially evenly spaced about a periphery of the inner bore

015642. In another specific embodiment, as best shown in Figure 7, which is an enlarged view of a portion of the safety valve shown in Figure 1A, the lockout sleeve 40 may include a shoulder 50

0157having a first face 52, and the annular fluid passageway 46 and the plurality of fluid injection

0158ports 48 (Figure 2) may be disposed in the first face 52. This embodiment may also be provided

0159with a sealing ring 54 disposed adjacent the first face 52, and a retainer ring 56 for securing the

0160sealing ring 54 to the first face 52. In a specific embodiment, the sealing ring 54 may be made

0161of Teflon, or other suitable compliant material.

0162In another specific embodiment, as shown in Figure 1A. the safety valve 10 of the present

0163invention may be provided with one or more devices to prevent backflow of injection fluids from

0164the flowpath 38 into the fluid injection conduit 36. such as first and second one-way check valves

016558 and 60. In a specific embodiment, the check valves 58 and 60 may be disposed in series

0166relationship with the fluid flowpath 38 and the fluid injection conduit 36, and be in fluid

0167communication therewith. In this embodiment, in the event one of the check valves 58 or 60 fail,

0168the other valve will still function, thereby serving as a back-up or redundant valve. In a specific

0169embodiment, the check valves 58 and 60 may be O-ring or ball check valves, of a type well

0170known to those of skill in the art. In another specific embodiment, as shown in Figure 9. the

0171check valves 58 and 60 may be directly connected to one another in series relationship, instead

0172of having a section of control line disposed therebetween, as is the case with the embodiment

0173shown in Figure 1 A. Also, with reference to Figure 9. the first check valve 58 may be connected

0174directly to the body member 12, instead of having a section of conduit disposed between the first

0175check valve 58 and the body member 12, as is the case with the embodiment shown in Figure 1A.

0176In this manner, the number of leak paths may be reduced. It is to be understood that the scope

0177of the invention is not intended to be limited to any particular backflow prevention device, but that other devices that allow fluid flow in only one direction, as known to those of skill in the art, are intended to be within the spirit and scope of this invention.

0178Another specific embodiment of the valve 10' of the present invention is shown in

0179Figure 4, wherein the longitudinal bore 14' may include an annular groove 62 in fluid

0180communication with a fluid flowpath 38' in the body member 12', and with a plurality of fluid

0181injection ports 48' in the lockout sleeve 40'. The fluid flowpath 38' is in fluid communication

0182with a fluid injection conduit 36', which may be provided with one or more backflow prevention

0183devices, such as first and second one-way check valves 58' and 60', in the same manner as

0184discussed above in connection with Figures 1A and 9. The plurality of fluid injection ports 48'

0185are in fluid communication with the annular groove 62 and with an inner bore 42' of the lockout

0186sleeve 40'. In a specific embodiment, the plurality of fluid injection ports 48' may extend

0187radially inwardly from the annular groove 62 to the inner bore 42' and may be substantially

0188evenly spaced about a periphery of the lockout sleeve 40'.

0189Referring to Figure 1A. in another specific embodiment of the present invention, the

0190subsurface safety valve 10 may be provided with a testing device 72 in a section of control line

019136a between the first check valve 58 and the fluid flowpath 38 in the body member 12. In a

0192broad aspect, the function of the testing device 72 is to test the integrity of the fluid injection

0193conduit 36, and any fittings connected to the conduit 36. such as the check valves 58 and 60.

0194between the subsurface safety valve 10 and the fluid source 37 at the earth's surface 66 (see

0195Figure 8). In a more particular aspect, the function of the testing device 72 is to verify that there

0196are no leaks in the injection conduit 36. or in any related connection, and to verify that the

0197injection conduit 36, and any related connections, will operate at a minimum operating pressure.

0198The testing device 72 may be provided in numerous forms, as will be readily apparent to those of skill in the art, all of which are intended to be within the spirit and scope of the present invention.

0199Referring to Figure 5, in a specific embodiment, a testing device 172 may include a

0200housing 174 connected to the section of control line 36a, and a rupturable member 176 disposed

0201within an interior 178 of the housing 174. The rupturable member 176 is designed to restrict

0202fluid flow through the control line 36a unless a predetermined fluid pressure is exceeded, at

0203which time the rupturable member 176 will rupture and permit fluid flow through the control line

020436a. In a specific embodiment, the rupturable member 176 may be a rupture disc.

0205Referring to Figure 6, in another specific embodiment, a testing device 272 may include

0206a housing 274 connected to the section of control line 36a, and a plug 276 for mating with an

0207aperture 280 formed by a rupturable lip 280 inside the housing 274. Injection fluid pressure 282

0208forces the plug 276 into sealing relationship with the aperture 278 to restrict fluid flow through

0209the control line 36a. The testing device 272 is designed so that the lip 280 will fail at a

0210predetermined pressure. When the predetermined pressure is exceeded, the lip 280 will fail so

0211as to allow fluid to flow through the control line 36a. After the lip fails, the plug 276 will rest

0212against a first or second control conduit extension 284 or 286. each of which are provided with

0213flow ports 288 and 290, respectively. When fluid is flowing from the earth^'s surface 66 into the

0214safety valve 10. the plug 276 will rest against the second extension 286. and the injection fluid

0215will flow through the flow ports 290 into the conduit 36a. If there should be any backflow

0216through the device 272, the plug 276 may be forced upwardly against the first extension 284. in

0217which case the injection fluid will be permitted to continue to flow upwardly through the flow

0218ports 288. It will be apparent to those of skill in the art that the purpose of the first and second extensions 284 and 286, along with their respective flow ports 288 and 290, is to prevent the plug

0219276 from blocking fluid flow through the testing device 272 after the lip 280 has ruptured.

0220It can now be seen that the safety valve 10 satisfies a primary objective of the present

0221invention by providing a system for injecting fluids — such as for chemicals for retarding

0222corrosion, scale, parafin, asphaltenes, and the like — into the longitudinal bore 14. In operation,

0223fluids may be transmitted, by operation of controls (not shown) at the earth's surface 66 (see

0224Figure 8) . down the fluid injection conduit 36/36', through the fluid flowpath 38/38', and into

0225the longitudinal bore 14/14'. If the safety valve 10/10' is provided with a plurality of fluid

0226injection ports 48/48'. such as in the lockout sleeve 40/40'. the fluid may be transmitted from the

0227fluid flowpath 38/38' through the plurality of fluid injection ports 48/48' and into the inner bore

022842/42'. In this manner, the injection fluids may be more evenly distributed inside the safety valve 10.

0229In accordance with another important object of the present invention, the fluid injection

0230conduit 36 and the fluid flowpath 38 may provide the safety valve 10 with a pressure equalization

0231feature to overcome a problem that may arise when moving the valve closure member 24 from

0232its closed to its open position. As explained above, when the closure member 24 is in its closed

0233position, well fluid pressure below the closure member 24 acting upon a relatively large surface

0234area of the valve closure member 24 makes opening of the member 24 difficult. By use of the

0235present invention, pressure above and below the closure member 24 may be equalized prior to

0236its opening, thereby significantly reducing the force required to open the closure member 24.

0237Referring to Figure 8, pressure equalization is achieved under the present invention by first

0238closing a valve 64. commonly referred to as the master valve, located at the earth's surface 66.

0239The valve 64 controls fluid flow from a well conduit 68 that is disposed within a well bore 69. The safety valve 10 of the present invention is connected to the well conduit 68. After closing

0240the master valve 64, pressurized fluid is pumped down the fluid injection conduit 36. through the

0241internal fluid flowpath 38, and into the longitudinal bore 14 above the closure member 24. The

0242pressurized fluid is pumped into the bore 14 until a chamber 70 that is formed within the well

0243conduit 68 above the closure member 24 and below the closed master valve 64 is fully occupied

0244by pressurized fluid and the pressure above and below the closure member 24 is equalized.

0245Hydraulic pressure from a source of hydraulic fluid 33 at the earth's surface 66 may then be

0246applied through the hydraulic control conduit 32 to the safety valve 10 to open the closure

0247member 24 in a manner known to those of ordinary skill in the art.

0248It is to be understood that the invention is not limited to the exact details of construction,

0249operation, exact materials or embodiments shown and described, as obvious modifications and equivalents will be apparent to one skilled in the art. For example, while the present invention has been described in relation to a particular type of safety valve, namely a "rod-piston^" type

0250safety valve, similar to the one shown in U.S. Pat. No. 4.161.21 . it should be understood that

0251the present invention may be used in any commercially available safety valve, whether it be

0252tubing conveyed, wireline conveyed, hydraulically operated, or electrically operated.

0253Accordingly, the invention is therefore to be limited only by the scope of the appended claims.