Surface Operated, Subsurface Safety Valve Assembly

Abstract

Opening and closing of a subsurface safety valve in a well tubing is regulated by control pressure supplied to the valve through a pressure passage extending from the valve to the well surface. Reduction in control pressure in the passage permits the valve to move to its normally closed position under the influence of a compressed spring. Repressuring the passage acts through an expansion chamber to reopen the valve against the force of the spring. A pressure bypass is provided for equalizing pressures above and below the closed valve to ease reopening of the valve. The valve may be permanent or retrievable, and in one form of the invention, a retrievable valve is landed within an inoperative, permanent safety valve. In the latter embodiment, means are provided for regulating opening and closing of the retrievable valve by pressure supplied through the pressure passage previously regulating operation of the permanent valve. In one form of the invention, the passage is provided by a small control line and in another form, the passage is provided between two concentric tubing strings.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to automatic valving means employed to terminate the flow of fluids through a well structure. More specifically, the present invention relates to a subsurface safety valve which is controlled from the well surface to close in the event of damage to the confining structure at the wellhead.

2. Description of the Prior Art

The prior art conventionally employs surface operated subsurface valves which open or close a production tubing string in response to hydraulic pressure supplied through a small control line extending between the subsurface valve and the well surface. In operation, loss of pressure in the control line, which may be caused by damage to the wellhead structure and the attached control line, permits a spring loaded valve in the production tubing string to move to closed position to terminate the flow of well effluents through the string. An example of this type valve is illustrated in U. S. Pat. No. 3,092,135.

Where such valves are "in-place" or permanent valves forming a fixed part of the production tubing string, replacement or repair of the valve requires removal of the entire tubing string. The expense and lost production time associated with complete removal of the tubing string are highly undesirable. Normally, in-place valves are desirable to the extent that they afford the use of large flow passages through the valve elements.

Another problem associated with surface operated, subsurface safety valves of the type previously described is that once closed, such valves are difficult to reopen because of the pressure differential developed across the valve closure elements. Customarily, to reopen such valves, it is necessary to repressure the production tubing string from the wellhead until the pressures above and below the closure elements are equalized.

In some applications, it may not be desirable to employ a separate, small control line which extends from the subsurface valve to the well surface. Such use may be undesirable for example where production is being effected simultaneously through several zones and the small line is carried in the annular area used to produce one of the zones. Flow of sandy effluents through the annular area may eventually cut through the control line permitting loss of pressure which in turn would cause closure of the subsurface valve.

SUMMARY OF THE INVENTION

In the preferred form of the invention, an in-place or permanent surface operated, subsurface safety valve assembly is designed to act as a landing nipple for a retrievable subsurface valve assembly whereby the retrievable valve may provide the safety valving function previously supplied by the in place-valve. In this manner, the desired subsurface safety function may be restored without the need for complete removal of the production tubing string.

In the latter embodiment, both the in-place valve and the retrievable valve are equipped with pressure by-passes which permit equalization of pressure above and below the closed valve elements so that the control pressure is sufficient to reopen the valve.

In one form of the invention, the control pressure passage is formed in the annular space included between two concentric tubing strings which extend between the subsurface valve location and the well surface. In the latter embodiment, a retrievable valve mechanism is movable through the central tubing string and is operable by hydraulic pressure supplied through the annular control passage to terminate effluent flow through the internal tubing string.

From the foregoing it may be appreciated that one object of the present invention is to provide an in-place, subsurface, surface-operated safety valve which, in the event it should become inoperable, may function as a landing nipple for a retrievable valving assembly which is also surface operated.

Another object of the present invention is to provide a control pressure passage in the form of an annular space formed between two concentric tubing strings exending between the subsurface valve and the well surface.

Still another object of the present invention is to provide a pressure equalizing means whereby high pressure differentials existing across closed valve members may be equalized to permit the subsurface valve to be easily reopened.

The foregoing objects of the invention and other features and advantages of the invention will be more readily appreciated from the following specification, drawings and the related claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are elevations, in quarter section, illustrating the upper and lower portions respectively of one form of the surface-operated, subsurface valve assembly of the present invention;

FIGS. 2A and 2B are the upper and lower portions respectively of the valve assembly of FIG. 1 in open position;

FIGS. 3A and 3B are vertical quarter sections of the upper and lower portions respectively of the assembly of FIG. 1 illustrating a lock-out mechanism conditioning the assembly for receipt of a second valve assembly;

FIGS. 4A and 4B are similar to FIGS. 3A and 3B illustrating the operation of the lock out mechanism;

FIGS. 5A and 5B illustrate a retrievable valve assembly landed in the assembly of FIG. 1;

FIGS. 6A and 6B are similar to FIGS. 5A and 5B, illustrating the retrievable valving assembly in open position;

FIGS. 7A and 7B are vertical quarter sections illustrating the upper and lower portions respectively of a modified valve assembly illustrated in closed position;

FIGS. 8A and 8B are vertical quarter sections illustrating the upper and lower portions respectively of another modification of the present invention employing an annular pressure control passage; and

FIGS. 9A and 9B illustrate the assembly of FIG. 8 in open position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

One form of the present invention is illustrated in FIGS. 1A and 1B which show the upper and lower portions, respectively, of a surface-operated, subsurface safety valve assembly indicated generally at 10. The assembly 10 is included as part of a production tubing string T which extends between a wellhead (not illustrated) and a subsurface petroleum bearing formation (not illustrated) to convey effluents in the formation to the well surface in a well-known manner. The assembly 10 includes a plural part outer housing body formed by tubular members 11, 12, 13, 14 and 15 which are threadedly connected to each other to form a composite tubular body which is connected at its upper and lower ends into a production tubing string T. O-ring seals are disposed between the mating parts in the outer housing to prevent leakage.

A primary tubular control sleeve 16 carried internally of the outer housing is adapted to be moved axially through the housing to regulate opening and closing of a flapper valve closure assembly indicated generally at 17. The control sleeve 16 is formed from upper and lower, threadedly engaged segments 18 and 19. A coil spring 20 extends concentrically within an annular space 21 formed between the lower sleeve section 19 and the outer housing member 13. The spring 20 is compressed axially between the base of upper sleeve section 18 and the upper end of housing section 14 and biases the sleeve 16 upwardly.

The valve assembly 17 is carried in the outer housing member 14 and includes a flapper closure member 22 which is pivotably mounted about a supporting pin 23. A spring 24 encircles the pin 23 and biases the closure member 22 to closed position. In its closed position, an O-ring seal 25 carried on the sealing surface of the flapper element 22 engages and seals agianst an annular seat member 26 carried in the housing member 14. A recess 27 formed along the internal surface of the housing component 14 receives the flapper element 22 when the flapper is rotated into its open position illustrated in FIG. 2B.

In operation, hydraulic pressure is supplied to the assembly 10 through a small control line 28 which is in pressure communication with a port 29 formed through the housing component 12. Hydraulic fluid in the line 28 flows through the base of the line into the port 29 where it is communicated to an expansion chamber 30 formed between the housing member 12 and the control sleeve segment 18. Upper and lower O-ring seals 31 and 32, respectively, form a sliding seal between the control sleeve component 18 and housing component 12. The cross-sectional area of the sliding seal formed by the O-ring 31 is less than that of the 0-ring 32 with the result that the control sleeve 16 is moved axially downwardly through the outer housing when the fluid pressure in the chamber 30 is sufficiently greater than the external pressure to compress the spring 20.

The initial downward movement of sleeve 16 from the position illustrated in FIGS. 1A and 1B moves an O-ring seal 33 out of sealing engagement with the internal surface of the housing member 12 to open a bypass which permits equalization of pressures existing above and below the closed flapper valve 22. In operation, the bypass functions to communicate the pressure in the assembly 10 below the flapper valve 22 through an axially extending opening 34 formed in the housing component 14 to a bypass line 35 which is in pressure communication with a port 36 opening through the housing component 12 to an annular space 37 formed between the control sleeve 16 and the surrounding outer housing. With the seal 33 below the base of member 12, the pressure in the annular passage 37 is communicated through a radial port 38 into the assembly 10 above the flapper valve 22.

Initially, the pressure supplied through the control line 28 is sufficient to lower the control sleeve 16 enough to release the seal formed by O-ring 33 so that fluid pressure below the flapper valve 22 is bypassed around the valve. The sleeve 16 is retained in this position until the pressures above and below the flapper element 22 are substantially equal at which point, the pressure in chamber 30 is sufficient to compress the spring 20 causing the sleeve 16 to move axially downwardly until it engages the flapper 22. The downwardly moving sleeve rotates the flapper about the pin 23 into the recess 27. When the sleeve 16 is shifted to its lowermost position, the valve assembly 10 is fully opened as illustrated in FIGS. 2A and 2B. In the latter position, the control sleeve segment 19 engages an O-ring seal 39 carried in a seal 40 so that the sealing surfaces on the flapper element 22 and seat member 26 are protected from the abrading and corrosive effects which may be caused by well effluents flowing through the assembly 10.

In use, the assembly 10 is normally maintained in its open position as illustrated in FIGS. 2A and 2B. In the event pressure supplied through the line 28 is lost, as may occur for example from wellhead damage, the pressure in chamber 30 falls sufficiently to permit the spring 20 to shift the sleeve 16 upwardly permitting the spring 24 to swing the flapper element 22 into the closed position illustrated in FIG. 1B. When in the closed position, all effluent flow through the tubing string T is terminated. When the wellhead damage or malfunction has been corrected, the valve 17 may be reopened by repressuring the line 28 to shift the sleeve 16 downwardly sufficiently to open the pressure bypass around the valve in the manner previously described. Subsequently, with the pressure across the flapper equalized, the pressure in control line 28 is sufficient to snap the flapper 22 into the fully opened position illustrated in FIG. 2B.

The valve assembly 10 is maintained in its open position when it is initially being run into the well by pressuring the chamber 30 at the well surface. While pressure is being supplied to the chamber 30, the assembly 10 is inverted which permits a ball 41 to rest and seal against an annular O-ring seal 42 carried in a seating surface 43 formed at the base of the pressure line 28. When the pressure being supplied through line 28 is released, the back pressure in chamber 30 maintains the ball 41 against the O-ring 42 so that the ball acts as a check valve which prevents loss of pressure in the chamber 30 and maintains the valve 17 in open position. Once the valve assembly has been lowered to its subsurface position, pressure supplied through the line 28 permits the ball 41 to fall to the bottom of an axial retaining bore 44 formed in the housing member 22.

In the event the valve assembly 17 should become inoperative, the assembly 10 is adapted to receive a second, retrievable, surface-operated safety valve. The assembly 10 is conditioned to receive the retrievable valve by a surface operated lock-down mechanism indicated generally at 45 in FIGS. 3 and 4. Referring initially to FIG. 3, the mechanism 45 is designed to shift the sleeve 16 to its lowermost position and to lock it in that position by shifting a hold-down collar 46 downwardly through the outer housing body. To this end, the lock-down mechanism 45 is lowered through the tubing string T into the position illustrated in FIGS. 3A and 3B. The required axial movement of the assembly 45 may be regulated from the surface by any suitable means, including wireline, hydraulic pumping means, or otherwise.

The assembly 45 includes a rod 47 having an enlarged foot piece 48 secured at its lower end. The upper end of the rod 46 is threadedly engaged with a rod section 49 which is in turn engaged at its upper end to a turular member 50. A connector member 51 is secured by means of a shear pin 52 within the upper tubular opening of rod member 50. The upper end of component 51 connects to a conventional wireline (not illustrated) which is employed to return the assembly 45 to the well surface.

In the preferred form, the assembly 45 is pumped into position from the wellhead and for this purpose, suitable annular packing 53 is carried about the external surface of the component 50. The packing 50 cooperates with an internally positioned O-ring seal 54 to provide a pressure barrier in the tubing string T. Pressure applied from the well surface above the pressure barrier "pumps" the assembly 45 downwardly through the tubing string T until one or more spring loaded dogs 55 register with locating recesses 56 and 57 formed along the internal surface of the housing member 15. In the latter position, springs 58 snap the dogs 55 radially outwardly so that projections 59 and 60 on the dogs spring into the recesses 56 and 57, respectively. The dogs 55 are pivotably carried in a tubular support body 61 which forms the lower end of a composite sleeve 62. The sleeve 62 includes a second tubular body portion 63 which is pinned to an upper tubular portion 64 by means of a shear pin 65. An externally developed projection 66 at the base of member 64 engages an internally developed projection 67 at the upper end of a component 63 to prevent the two components from separating. The upper end of the sleeve 62 is threadedly engaged to a tubular holding component 68.

When the assembly 45 has been pumped to the subsurface location illustrated in FIGS. 3A and 3B, the dogs 55 spring open in the manner described to release the foot piece 48 which had been trapped in an internal recess 69 formed along the radially inner surface of the dogs 55. When thus located and with the rod 47 released, the mechanism 45 is raised by an upward pull exerted by the surface extending wireline connected to the top of the mechanism. A compressed coil spring 71 encircling the rod 47 urges the rod upwardly and the sleeve 62 downwardly when the wireline is raised. The action of the spring 71 cooperates with the partial locking provided by the dogs 55 to permit the rod 47 to be moved upwardly through the sleeve 62. Upward movement of the rod through the upper sleeve section 38 permits one or more spring loaded dog members 72 to spring radially outwardly under the influence of a U-type spring 73. A lower projection 74 extending downwardly from the base of the dogs 72 engages an upwardly extending lip 75 on the sleeve component 68 to limit the outward radial expansion of the dogs 72. Upward movement of the rod through the sleeve component 68 also compresses a snap ring 76 which permits the rod to be raised above a shoulder 77 exending radially inwardly from the sleeve component 68. The flat base of the ring 76 engages the top of projection 77 and prevents the rod from returning to its original position.

FIG. 4A illustrates the dog 72 extending radially outwardly and the rod 47 shifted upwardly with respect to the surrounding sleeve component 68. When in the expanded position, a downwardly directed face 78 on the dog 72 engages the top of the lock-down collar 46. The lock-down collar includes a plurality of upwardly extending resilient collet fingers 79 having enlarged locking heads 80 at their upper end. When the valve 17 is functioning properly, the heads 80 lock with an annular recess 81 formed along the internal wall of the housing member 11 to maintain the collar in the position illustrated in FIGS. 1A and 2A. With the dogs 72 extended as illustrated in FIG. 4A, the assembly 45 is driven downwardly by hydraulic pressure applied from the wellhead or by suitable jarring mechanisms (not illustrated), or otherwise, to shift the hold-down collar 46 from the position illustrated in FIG. 1A to the lower position illustrated in FIG. 4A. The downward force acts through the snap ring 76 against the top of projection 77. When the force exerted on sleeve 62 is sufficiently great, the pin 65 shears permitting the sleeve segments 64 and 68 to shift downwardly from the position illustrated in FIG. 4A. Downward movement of the lower portions of sleeve 62 is prevented by engagement of a lower face 82 formed along the base of the dogs 55 with a flat face 83 formed at the lower end of the locating recess 57. Downward shifting of the locking collar 46 brings the collet heads 80 into engagement with an annular recess 84 formed in the internal wall of the outer housing. Lowering of the hold-down collar 46 is also effective to shift the operating sleeve 16 downwardly into the position illustrated in FIG. 4A. The collet heads 80 are provided with flat upper surfaces which engage the flat upper surface of the recess 84 to prevent the collar 46 and sleeve 16 from shifting upwardly under the influence of the coil spring 20.

With the sleeve 16 thus locked into its lower position, the lock-down assembly 45 may be withdrawn to the well surface. Raising of the surface extending wireline draws the rod 47 and sleeve segments 68 and 64 upwardly until the projection 66 engages projection 67 which draws the lower portion of the sleeve 62 upwardly. With the projections 66 and 67 engaged, the foot piece 48 aligns with the recess 69 and the upward pull exerted on the sleeve 62 draws tapered surfaces on the dogs 55 and recesses 56 and 57 into engagement causing the dogs to close radially inwardly against the spring force to permit the entire mechanism 45 to be withdrawn to the well surface.

If a pressure differential develops across the seal 54 and packing 53 as the mechansim 45 is being raised through the tubing T, the shear pin 52 severs permitting an enlarged base section 85 at the bottom of connecting member 51 to move up to and engage an internal shoulder 85 formed at the top of tubular rod member 50. In the latter position, the seal provided by O-ring 54 is disrupted and fluid above the assembly 45 is permitted to flow through axial openings 86 and radial openings 87 to prevent development of a pressure differential across the upwardly moving mechanism 45.

Once the sleeve 16 has locked in its lower position in the manner previously described, a suitable perforating mechanism (not illustrated) is lowered through the tubing string T and operated to form one or more perforations 88 (FIG. 5A) through the wall of control sleeve 16. Following formation of the perforations, a retrievable, surface operated safety valve assembly indicated generally at 89 in FIGS. 5A and 5B is lowered through the tubing string T and landed within the assembly 1. A suitable running tool (not illustrated) is employed to lower the retrievable assembly 89 into position and anchor it within the surrounding outer housing of assembly 10. In operation, the assembly 89 is designed to provide the same valving function previously provided by the assembly 10 with opening and closing of the valve controlled by pressure in the control line 28.

The valve assembly 89 includes a main body housing formed of threadedly engaged tubular members which include a lower dog holding member 90, a valve mounting member 91, a spring housing member 92, a connecting member 93, a chamber housing member 94, an upper connecting member 95, a locking dog carrying member 96 and an upper retrieving member 97. At each of the threadedly engaged junctions of the members forming the main body housing, O-ring sals are provided to ensure fluid-tight engagement between the components.

An axially movable, secondary control sleeve 98 is carried within the main body housing. A coil spring 99 concentrically positioned between the control sleeve 98 and the main housing functions to bias the sleeve 98 toward its upper axial position in the manner previously described with reference to spring 20. Axial movement of the sleeve 98 through the main housing body opens and closes a flapper valve assembly indicated generally at 100.

Control of the opening and closing of assembly 89 is similar to that previously described with reference to the assembly 10. Pressure in the line 28 is conveyed through the perforations 88 and through raidal ports 101 to an expansion chamber 102. Fluid in the annular area between the sleeve 16 and the main housing body is confined at the upper end of the area by an annular O-ring seal 95a and at the lower end of the annular area by O-rings 91a and 39. When the pressure in the chamber 102 is great enough to overcome both the external pressure and the force exerted by compressed spring 99, the sleeve 98 is shifted downwardly into the position illustrated in FIGS. 6A and 6B. In the latter position, the valve assembly 100 is in its fully open position where it is received in a recess shielded by the overlying secondary operating sleeve 98. In the event pressure in the line 28 is lost, the force of spring 99 returns the sleeve 98 to its upper position permitting a spring 103 to pivot a flapper valve closure member 104 into the closed position illustrated in FIG. 5B.

A pressure bypass is provided for reopening the valve 100. The bypass means includes O-ring seals 105 and 106 positioned respectively above and below radial port 107 extending through the wall of the sleeve 98 and a radial port 108 extending through the valve mounting member 91 below the O-ring 106 and above a third O-ring 109. With the valve in the closed position illustrated in FIG. 5B, the flapper element 104 cooperates with O-rings 109 and O-ring 91a to terminate effluent flow through the assembly. Repressuring the fluid in line 28 shifts the sleeve 98 downwardly bringing the port 107 below O-ring 106 to establish a pressure bypass through the ports 107 and 108. Pressure above and below the flapper 104 begins to equalize through the bypass and when the pressure differential across the flapper is substantially eliminated, the pressure exerted in chamber 102 is sufficient to snap the sleeve 98 downwardly into the position illustrated in FIG. 6B.

During the initial placement of the assembly 89 within the assembly 10, spring loaded dogs 111 spring radially outwardly into the locating recesses 56 and 57 when the assembly is properly positioned axially. Movement below this point is prevented by a flat lower surface 112 on the dogs 111 which engages the lower face 83 of recess 57.

At the upper end of assembly 89, an axially movable locking collar 113 is employed to shift locking dogs 114 radially outwardly into an annular recess 115. The collar 113 includes a snap ring 116 which is held axially below an internal shoulder 117 formed on the retrieving head 96 while the assembly 89 is lowered downwardly through the tubing string. When the collar 113 is in the latter position, recesses 118 and 119 formed along the external surface of the collar coincide with internally directed projections 120 and 121 respectively formed on the locking dogs 114 permitting the dogs to remain retracted. When the desired subsurface location is reached, the running tool is manipulated to draw the collar 113 axially upwardly with respect to the stationary main housing body causing the snap ring 116 to be depressed radially inwardly as it is being raised above the shoulder 117 permitting the collar to move into the position illustrated in FIG. 5A. The upward movement of the collar 113 with respect to the locking dogs 114 draws tapered surfaces at the ends of recesses 118 and 119 against oppositely tapered surfaces on the projections 120 and 121 to force the locking dogs 114 radially outwardly into locking engagement with the annular recess 115. With the dogs 114 in the latter locking position, the assembly 89 is anchored axially within the assembly 10.

Once the assembly 89 is locked in place, a shear pin 122 connecting the collar 113 with the running tool is severed to permit the running tool to be returned to the surface. The snap ring 116 prevents the sleeve 113 from falling axially below the projection 117 so that the dogs 114 are maintained in their radially outer position.

In the event it become necessary to retrieve the assembly 89 for any reason, a suitable retrieving mechanism (not illustrated) is lowered into the tubing string T and latched onto a retrieving shoulder 123 formed along the internal surface of the retrieving member 97. The retrieving mechanism shifts the collar 97 downwardly, until the snap ring 116 is below the projection 117, which permits radial retraction of the locking dogs 114. Once the dogs 114 have been freed from engagement with the recess 115, the assembly 89 may be withdrawn to the surface.

FIGS. 7A and 7B illustrate the upper and lower portions respectively of a modified surface operated subsurface safety valve assembly indicated generally at 110. The assembly 110 is similar in construction and operation to the assembly 10. The assembly 110 includes an outer assembly housing 111 and an internal operating sleeve 112. Axial movmeent of the sleeve 112 through the housing 111 regulates opening and closing of a flapper valve assembly indicated generally at 113. Fluid pressure for controlling movement of the sleeve 112 is supplied from the well surface through a control line 114. Pressure in line 114 is communicated to an expansion chamber 115. The upper and lower ends of the chamber 115 are sealed by O-ring seals 116 and 117, respectively, which form a continuous, sliding sealing engagement between the sleeve 112 and the surrounding housing 111. Pressure supplied to the chamber 115 shifts the sleeve 112 downwardly to compress a coil spring 117 and close the flapper valve 112. Loss of pressure in the chamber 115 permits the coil spring to return the sleeve 112 upwardly permitting a spring loaded flapper element in valve 113 to snap to closed position. A port 118 formed through the wall of the sleeve 112 communicates with the annular space between the sleeve 112 and the main housing 111 to prevent a fluid lock from developing during axial movement of the sleeve.

The assembly 110 is equipped with a pressure bypass means provided by axially spaced O-ring seals 119 and 120 and a flow passage 121 formed through the housing 111. When the assembly is in the position illustrated in FIG. 7B, the flow passage 121 is blanked off between the O-rings 119 and 120. With pressure reestablished in the chamber 115, the sleeve 112 is shifted downwardly to bring a radial port 122 formed through the wall of the sleeve 112 below the O-ring 119 and into fluid communication with the passage 121. In the latter position of the sleeve, pressures above and below the flapper element equalize permitting the pressure in chamber 115 to shift the sleeve 112 to its lowermost axial position.

When the assembly 110 becomes inoperative, a lock down tool is employed to shift a lock down collar 123 downwardly until locking heads 124 formed at the base of the collar latch into a recess 25 formed along the internal wall of the outer housing 111. With the collar 123 in the latter position, the sleeve 112 is locked in its lowermost position with the valve 113 fully open. Subsequently, one or more perforations are formed through the sleeve 112 at approximately the location P so that the chamber 115 may be in fluid communication with the pressure control means of a retrievable valve assembly such as the assembly 89 previously described. It will be appreciated that the lock-down mechanism employed to mainpulate the sleeve 123 and the retrievable valve employed in the assembly 110 are similar to those previously described with reference to the assembly 10. In addition, aspects of the assembly 110 not specifically described are similar or analogous to those previously described with reference to the assembly 10.

FIGS. 8 and 9 illustrate a modified form of the present invention indicated generally at 210. The assembly 210 includes concentric, inner and outer tubing sections 211 and 212, respectively, which extend between the subsurface valve location and the well's surface. The inner tubing section 211 connects with a tubular landing section 213 adapted to hold a retrievable, surface operated safety valve assembly indicated generally at 214. In operation, fluid pressure is supplied to the assembly 210 through an annular space 215 formed between the inner and outer tubing members 211 and 212. The lower ends of the sections 211 and 212 threadedly engage the upper end of a connecting sub 216. The lower end of the sub 216 is in turn connected to a tubing string (not illustrated) which is in fluid communication with a subsurface, petroleum bearing formation.

Pressure in annular chamber 215 is communicated through radial ports 217 formed through the walls of the landing section 213. A protective screen 218 encircles ports 217 to prevent debris from clogging or interferring with the workings of the internal components of the assembly 214. Fluid flowing through the ports 217 communicates with an annular passage 219 sealed at its upper and lower ends respectively by O-rings 220 and 221 carried on the retrievable valve assembly 214. The pressure in chamber 219 is in turn communicated through ports 222 to an expansion chamber 223 formed between a tubular valve housing body 224 and an internal tubular operating sleeve 225. Upper and lower sliding O-ring seals 226 and 227, respectively, enclose the expansion chamber 223 to permit the sleeve 225 to move axially through the surrounding housing 224 while maintaining a continuous sliding seal between the two components.

In operation, the fluid pressure in the annular passage 215 is employed to expand the chamber 223 causing the sleeve 225 to shift downwardly compressing a coil spring 228 carried between the sleeve 225 and the valve housing 224. The initial downward movement of the sleeve opens a pressure bypass in the manner previously described with reference to FIGS. 5B and 7B. Subsequent downward movement of the sleeve opens a flapper valve assembly indicated generally at 229 in the manner previously described with reference to other modifications of the invention. With the valve in the closed position illustrated in FIGS. 8A and 8B, the flapper valve assembly 229 cooperates with an O-ring 221 to completely terminate effluent flow through the assembly.

In the event it becomes necessary to retrieve assembly 214 from its subsurface location, a suitable retrieving mechanism is lowered through the tubing 211 and engaged with a retrieving shoulder 230. A locking sleeve 231 is shifted downwardly by the retrieving mechanism to release locking dogs 232, in the manner previously described, to permit the assembly 214 to be removed to the surface.

During placement of the assembly 214, a lower restriction 232 limits the downward axial movement of the assembly to properly locate it with respect to the surrounding landing section 213. When the proper location has been reached, the running mechanism shifts the hold-down sleeve 231 upwardly in the manner described previously with reference to FIG. 5A to lock the dogs 232 radially outwardly which in turn fixes the assembly 214 in position. Other features in the placement, retrieval and operation of the assembly are similar to those described earlier with reference to the assemblies 10 and 110.

While flapper valve closures have been employed to describe the operation of the present invention, it will be appreciated that ball closure members and other closures may be employed without departing from the teachings of the invention. Similarly, it will be understood that the annular control pressure flow passage described with reference to FIGS. 8 and 9 may be employed in the embodiments described in FIGS. 1-7.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and various changes in the size, shape and materials as well as in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention.

Claims

I claim:

1. A surface operated subsurface valve assembly for use in a well comprising:

a. subsurface valve means responsive to a control pressure for regulating flow of effluents through a well conduit;

b. control pressure passage means extending from said subsurface valve means toward the surface of said well for supplying control pressure to said valve means;

c. biasing means for urging said valve means to normally closed position wherein effluent flow through said well conduit is terminated;

d. opening means operable by said control pressure for opening said valve means against the action of said biasing means;

e. pressure equalizing means operable by said control pressure for reducing the pressure differential across said valve means when said valve means is closed whereby said opening means may fully reopen said valve means; and

f. check valve means openable by control pressure in said control pressure passage means for temporarily holding said subsurface valve means in open position while a relatively low control pressure is present in said passage means.

2. An assembly as defined in claim 1 wherein said valve means is retrievably positioned in said well conduit to permit placement and retrieval of said valve means from the well surface.

3. An assembly as defined in claim 2 wherein said control pressure passage means includes a second well conduit encircling said first named conduit to enclose a substantialy annular control pressure passage between said first mentioned conduit and said second conduit.

4. An assembly as defined in claim 1 wherein said control pressure passage means includes a second well conduit encircling said first named conduit to enclose a substantially annular control pressure passage between said first mentioned conduit and said second conduit.

5. An assembly as defined in claim 1 further including a second valve means retrievably positioned in said first mentioned valve means and operable by said control pressure for regulating flow of effluents through said well conduit.

6. An assembly as defined in claim 5 wherein said second valve means includes;

a. second biasing means for urging said second valve means to normally closed position;

b. second opening means operable by said control pressure for opening said second valve means against the action of said second biasing means; and

c. second pressure equalizing means operable by said control pressure for reducing the pressure differential across said second valve means when said second valve means is closed whereby said second opening means may fully reopen said second valve means.

7. An assembly as defined in claim 5 wherein said first mentioned valve means includes selectively operable means for retaining said first mentioned valve means in open position irrespective of the control pressure value.

8. An assembly as defined in claim 1 wherein said valve means includes selectively operable means for retaining said valve means in open position irrespective of the control pressure value.

9. An assembly as defined in claim 1 further including:

a. a substantially tubular valve housing body means;

b. a substantially tubular control valve means, carried in said housing body means.

c. a flapper valve closure element means operable by axial movement of said control sleeve means to open or close said well conduit to effluent flow;

d. coil spring biasing means carried concentrically between said control sleeve means and said housing means for normally biasing said sleeve means in a direction to move said closure element means to closed position; and

e. expansion chamber means communicating with said control pressure and operable by said control pressure to expand and to move said sleeve means in a direction moving said closure element means to open position.

10. An assembly as defined in claim 9 wherein said bypass means includes means operable upon limited movement of said sleeve means to open a relatively small pressure passage means communicating with the area in said well conduit above and below said valve means.

11. A surface operated, subsurface valve assembly for use in a well comprising:

a. a first subsurface valve means responsive to a control pressure for regulating flow of effluents through a well conduit;

b. control pressure passage means extending from said subsurface valve means toward the surface of said well for supplying control pressure to said valve means;

c. biasing means for urging said valve means to normally closed position;

d. opening means operable by said control pressure for opening said valve means against the action of said biasing means;

e. landing means in said valve means for landing a retrievable, second valve means in said first mentioned valve means;

f. means for operating said retrievable valve means by said control pressure to regulate the flow of effluents through said conduit; and

g. check valves means openable by control pressure in said control pressure passage means for temporily holding said subsurface valve means in open position while a relatively low control pressure is present in said passage means.

12. An assembly as defined in claim 11 wherein said first mentioned valve is in fully open position and said retrievable valve means is landed and locked in said first mentioned valve means.

13. An assembly as defined in claim 12 wherein said second valve means includes:

a. second biasing means for urging said second valve means to normally closed position;

b. second opening means operable by said control pressure for opening said second valve means against the action of said second biasing means; and

c. a second pressure equalizing means operable by said control pressure for reducing the pressure differential across said second valve means when said second valve means is closed whereby said second opening means may fully reopen said second valve means.

14. An assembly as defined in claim 12 wherein said second valve means further includes second pressure equalizing means operable by said control pressure for reducing the pressure differential across said second valve means when said second valve means is closed whereby said second opening means may fully reopen said second valve means.

15. An assembly as defined in claim 11 wherein said landing means includes selectively operable means for retaining said valve means in open position irrespective of the control pressure value.

16. An assembly as defined in claim 11 wherein said valve means includes:

a. a substantially tubular valve housing body means;

b. a substantially tubular control sleeve means carried in said housing body means; and

c. a flapper valve closure element means operable by axial movement of said control sleeve means to open or close said well conduit to effluent flow.

17. An assembly as defined in claim 11 further including pressure equalizing means operable by said control pressure for reducing the pressure differential across said valve means when said valve means is closed whereby said opening means may fully reopen said valve means.

18. An assembly as defined in claim 1 wherein said check valve means includes a ball, a seat and a ball recess below said ball whereby application of control pressure to said control pressure passage means unseats said ball and permits said ball to fall into said ball recess.