Annulus pressure controlled testing apparatus

Abstract

An annulus pressure controlled testing tool is disposed in a well bore above a packer which is set in the well bore and separates the productive earth formation from the annular space above the packer. The testing tool is a shut-in valve assembly having a valve openable for successive periods under the control of an annulus pressure actuated escapement mechanism which allows the formation fluid to flow through the shut-in valve for a desired period of time.

Description

BACKGROUND OF THE INVENTION

Testing tools or apparatus for use in performing drill stem tests of earth formations are well known. An example is the drill stem fluid sampler of my prior U.S. Pat. No. 3,437,138, granted Apr. 8, 1969.

Typically, drill stem testing tools have been operated in response to rotation or longitudinal movement of the string of drill pipe in which the testing tool is installed and by which the testing tool is run into the well. When the testing operations are being performed from a stable platform, in most cases, these prior tools have been quite satisfactory, since the rotative or longitudinal movement of the drill string can be readily accomplished with the usual hoist mechanism. However, in the case of slant-hole drilling or drilling from an unstable platform, such as a floating vessel, the control of testing tools by manipulation of the pipe is very difficult. When slant-hold drilling, friction of the drill pipe within the well casing renders very uncertain the actual position or orientation of the drill pipe at any given depth due to twist or stretch of the pipe. When performing a drill stem test from an unstable platform such as a floating or partially submerged vessel or platform in the ocean which is subject to motion caused by tidal and wave action, longitudinal movement of the drill pipe string cannot be relied upon for the control of drill stem testing equipment.

Another problem encountered in the performance of drill stem testing operations from a floating or partially submerged platform is that in the event of heavy seas, the platform may be pulled from its moorings rupturing the drill pipe string between the vessel and the downhole drill stem tester. If the drill stem tester does not automatically close, then well fluid may flow into the sea.

SUMMARY OF THE INVENTION

The present invention provides a shut-in valve for drill stem testing of a productive earth formation traversed by a well bore, wherein the shut-in valve is normally closed by formation pressure and is adapted to be opened by the application of pressure to the annulus above a packer which isolates the productive formation. With such a drill stem tester or formation testing tool, a bumper sub or telescopic joint can be employed in the drill pipe string above the shut-in valve to compensate for the rise and fall of the floating or semi-submerged platform. In the event the drill pipe string ruptures for any reason, a normally closed shut-in valve will confine the productive formation fluids against flow into the sea.

More particularly, the shut-in valve is constructed to enable it to be successively opened and closed to enable a series of drill stem tests, under the control of an escapement mechanism activated in response to the pressure of fluids in the annulus above the packer and spring means adapted to be overcome by annulus fluid pressure to release the escapement mechanism for one increment of motion. The spring means comprises a stack of Belleville spring washers which occupy a small space and which may have a constant spring rate.

The shut-in valve and the escapement mechanisms are influenced by the pressure of formation fluid below the packer to hold the shut-in valve closed. When the escapement mechanism is released, the formation pressure acts on the shut-in valve to shift the shut-in valve to an open position. In the absence of sufficient formation pressure to effect opening of the shut-in valve, the testing tool also includes energizing means responsive to pressure in the annulus above the packer to assist in the shifting of the shut-in valve to an open position.

Since under some differential pressure conditions the forces acting to open the shut-in valve may be substantial, the tool also includes buffer means for limiting the rate of movement of the shut-in valve towards the open position, thereby minimizing potentially destructive inertia forces otherwise applicable to the escapement mechanism.

Among the objects of the invention is the provision of a drill stem testing tool which is particularly well suited for performing drill stem testing operations in a well drilled from a floating or partially submerged platform subject to vertical motion caused by tide or wave action, the tool being operable by annulus fluid pressure and being safe and reliable in its operation.

This invention possesses many other advantages, and has other purposes which may be made more clearly apparent from a consideration of the form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principals of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagramatic view illustrating a testing tool string in accordance with the invention and disposed in a well bore;

FIGS. 2a through 2c together constitute a view partly in elevation and partly in longitudinal section illustrating the shut-in valve of the invention in a running-in condition;

FIG. 3 is a transverse section as taken on the line 3--3 of FIG. 2b;

FIG. 4 is a transverse section as taken on the line 4--4 of FIG. 2b;

FIG. 5 is a transverse section as taken on the line 5--5 of FIG. 2b;

FIG. 6 is a transverse section as taken on the line 6--6 of FIG. 2c;

FIG. 7 is an enlarged fragmentary detail view in longitudinal section illustrating the Belleville spring pack centering means;

FIGS. 8a through 8c together constitute a view partly in elevation and partly in longitudinal section illustrating the shut-in valve of the invention in a testing condition;

FIG. 9 is an enlarged fragmentary view in longitudinal section showing the escapement mechanism in the running-in condition;

FIG. 10 is a view corresponding to FIG. 9, but showing the escapement mechanism in the testing condition; and

FIG. 11 is a view corresponding to FIGS. 9 and 10, but showing the escapement mechanism in the retrieving condition.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As seen in the drawings referring first to FIG. 1, a testing tool string S is shown in a well bore W in which casing C has been set and perforated at P to establish communication between a productive formation F and the inside of the casing C. At its lower end, the testing tool string S has a perforated testing instrument I which is adapted to record flow, and if desired, pressure and/or temperature of production fluid flowing from the formation F upwardly through the testing tool S under the control of the annulus controlled shut-in valve assembly V, in accordance with the invention. Between the shut-in valve V and the instrument I is a typical hook-wall packer assembly H adapted to form a seal with the casing C, as is well known. Such packers are adapted to be set in the well bore with slips 10 in anchoring engagement with the casing C, and with resilient packing ring elements 11 deformed into sealing engagement with the casing C to isolate the annular space 13 above the packer H. Preferably, the tool string S includes above the packer H an unloader valve assembly U openable when it is desired to retrieve the testing tool string S to balance the fluid between the annuli 12 and 13. Above the testing tool V is a drill pipe string D adapted to extend to the platform at the top of the well, and, as will be recognized by those skilled in the art, when the platform is a floating or partially submerged platform, the pipe string D will incorporate a bumper sub or telescopic joint adapted to compensate for relative vertical movement between the platform and the stationary elements anchored in the casing C by the packer H.

Referring particularly to FIGS. 2a through 2c, the shut-in valve assembly V is shown in detail in a condition with the shut-in valve means closed. The shut-in valve assembly comprises an elongated outer tubular assembly including an upper energizing section 15, beneath which is a buffer section 16, escapement mechanism section 17, and a valve section 18. Extending longitudinally within the tubular assembly is an inner tubular mandrel, generally denoted at 19, through which fluid from the formation F is adapted to flow when the shut-in valve means is actuated by annulus fluid pressure above the packer 14.

At its lower end, the tubular mandrel 19 is connected by a coupling 20, sealed by an O-ring 21, to a downwardly extending, elongated valve sleeve 22 having a plug 23' closing its lower end. This valve sleeve is reciprocable within a stationary cylindrical valve body 23, and the valve sleeve 22 has a vertically spaced series of ports 24, 25, 26, and 27 located between vertically spaced sealing rings collectively designated 28. The sealing rings 28 prevent the passage of fluid between the valve sleeve and the inner wall of the valve body 23, these seals being spaced above and below annular grooves 29 with which the respective ports 24 through 27 communicate. In the valve body 23 is a set of radial valve ports 30 spaced circumferentially of the body and communicating with the annular space 31 defined between the valve body 23 and an outer tubular body section 32, which has at its lower end a threaded pin 33 adapted for connection to the downwardly extending test string, say to the upper end of the unloader valve u, as shown in FIG. 1. The fluid in the annular space 31 will be the fluid which enters the well through the perforations P, enters the testing instrument I, enters the packer H and passes on upwardly into the annular 31. As will be later described, the valve sleeve 22 is adapted to move progressively upwardly in increments of motion so that the ports 24, 25, 26 and 27 are progressively in communication with the valve ports 30, and alternatively, the valve ports 30 are closed off between the progressively vertically spaced sealing rings 28.

The valve body 23 is fixedly mounted within the outer body section 32 by means of a spider formed by radiating flanges 34 projecting outwardly from the valve body 23 in the region of the ports 30 into centering engagement within the outer body 32, these ribs setting on a shoulder 35 within the body 32. At its upper end, the valve body 23 has a radially outwardly extended flanged section 36 engaged within the outer body 32, and provided with sealing rings 37, the flange 36 abutting with the lower end of an upwardly extended tubular outer body section 38 which is threaded into and sealed at 39 in the upper end of the lower body section 32.

As is apparent in FIG. 2c, the lower end of the valve sleeve 22 is exposed to the pressure of fluid coming from the formation F which provides a force biasing the valve sleeve 22 and the entire mandrel assembly 19 upwardly. This upward movement is assisted by the energizing section 15 of the tool, is dampened by the buffer section 16 of the tool, and is controlled by the escapement section 17 of the tool.

The energizing section 15 comprises an upper and outer main body 40 of tubular form threaded, as at 41, to the upwardly extending drill pipe string D. Within the body 40 is a cylinder sleeve 42 having a pair of vertically spaced outer sealing rings 43 sealingly engaged within the cylindrical inner wall of the body 40. The cylinder sleeve 42 has a reduced diameter mid-section 44 between the seal rings 43 and opposed by the inner wall of the body 40 to form a chamber 45 which communicates with a radial port 46 in the cylinder sleeve 42. The port 46 leads to an inner annular chamber 47 defined between upper and lower sealing rings 48 which slideably engage the upper section 49 of the inner mandrel assembly 19. At its upper end, the mandrel section 49 is of an enlarged diameter to provide a differential piston area 50 within the chamber 47 on which pressure acts to complement the force derived from well fluid pressure acting to shift the mandrel assembly 19 upwardly. The pressure acting on the piston area 50 is the pressure in the well bore annulus 13 above the packer H. Since such fluid is not clean fluid, means are provided for transmitting the annulus fluid pressure to the piston area 50 while protecting the working parts from the annulus fluid.

More particularly, the body 40 has a reduced mid-section 51 spanned by a circular bladder 52. At its upper end, the bladder has a bead 53 clamped against the body 40 by a gage ring 54. At its lower end the bladder has a similar bead 55 clamped against the body 40 by a gage ring 56. A slotted protective sleeve 57 is disposed about the bladder between the gage rings 54 and 56. The bladder and the body portion 51 define a chamber 58, a clean fluid such as oil being utilized to fill the chamber 58, as well as the annular space 45, between the body 40 and the cylinder sleeve 42 and the chamber 47 between the cylinder sleeve 42 and the mandrel section 49. Suitable fill and bleed openings and passages are provided at 59 and 60.

The buffer section 16 comprises an elongated cylinder 61 threaded at 62 to the lower end of the cylinder sleeve 42 and extends downwardly within an upper outer body section 63. At the lower end of the cylinder 61 is a head 64 slideably and sealingly engaged with a lower inner mandrel section 65 which is threaded at 66 to the above described upper mandrel section 49. At its lower end, the mandrel section 49 has a flange 67 slideably and sealingly engaged within the cylinder 61 and having an orifice 68. During assembly, the annular space 69 between the cylindrical sleeve 61 and the mandrel section 49 above the cylinder head 64 is filled with fluid such as oil, so that upward movement of the mandrel assembly 19 is dampened due to the transfer of oil through the orifice 68 as the mandrel moves upwardly.

From the foregoing, it will be recognized that upward movement of the mandrel 19 is adapted to establish communication successively between the valve sleeve ports 24, 25, 26 and 27 and the valve body ports 30, so that fluid from the well bore below the well packer H is enabled to flow upwardly through the shut-in valve assembly V, and more particularly, through the tubular mandrel 19, and thence into the drill pipe string D. Such flow is controlled by a conventional choke 70 comprising a tubular body 71 having a flow passage 72 in which is installed the usual flow bean 73 having a flow controlling orifice 74. It is desired that the mandrel 19 be moved upwardly to establish communication between the valve sleeve ports 24 through 27 and the valve body ports 30 in response to an increase in the pressure of fluid in the annulus 13 between the well casing and the valve assembly V, and that the increments of motion of the inner mandrel 19 correspond to the axial spacing between the valve ports 24 through 27.

The escapement mechanism 17 of the invention is provided to accomplish these purposes, and includes a stop mechanism 75 normally biased by spring means 76 to cooperate with the mandrel 19 to limit upward movement of the mandrel 19. Annulus pressure responsive means 77 is provided for operating the stop mechanism 75 and to allow an increment of upward movement of the mandrel 19 in response to the application of pressure to the fluid in the annulus 13, whereby the shut-in valve assembly V is operable independently of pipe string motion, while the lower portion of the pipe string D and the shut-in valve, as well as the test instrument I, are all precisely located within the well bore with respect to the formation F to be tested.

The escapement mechanism comprises an outer housing or tubular body 78 threadedly connected at 79 to the lower end of the previously described upper housing 63 and threadedly connected at 80 at its lower end to the previously described lower body section 38. Within the housing 78 is an axially shiftable, annular indexing guide 81. Concentric within the indexing guide 81 is an annular ball cage 82 having a supporting flange 83 disposed between a stop shoulder 84 in the housing 78 and the upper end shoulder 85 on the body 38, whereby the ball cage 82 is fixed with respect to the indexing guide 81 in the housing 78. The ball cage 82 has an upper set of circumferentially spaced balls 86 disposed and captive in radial openings 87 in the cage 82 and constituting upper detent means and a lower set of circumferentially spaced balls 88 disposed and captive in radial openings 89 in the cage 82 and constituting lower detent means. The arrangement of the balls 86, as shown in FIG. 5, is typical of the sets of balls 86 and 88. These balls 86 and 88, as will be more particularly described hereinafter, cooperate with a number of axially spaced lands 230, 240, 250, 260 and 270 spaced longitudinally of a section 90 of the tubular mandrel 19 to progressively locate the valve sleeve 22 to open and close the shut-off valve means, when annulus fluid pressure applicable to the pressure responsive means 77 is increased and decreased.

The spring means 76 normally acts to shift the indexing guide 81 in a downward direction. In the form shown, the spring means comprises a cartridge including a stack of frusto-conical spring washers 91 disposed in peripheral engagement so as to be axially deformed, such spring washers being generally known as Belleville springs. The stack of Belleville springs, as shown, is constructed and supported so as to minimize hysteresis which can be caused by the centering of the Belleville springs on inner or outer centering means. Such a stack of spring washers is more particularly the subject of the co-pending application for U.S. Pat. Ser. No. 430,980, filed contemporaneously herewith, in the name of Felix Kuus, for "Belleville Spring Cartridge." The Belleville spring cartridge, as herein illustrated, comprises an inner sleeve 92 disposed within the outer body 78 and supported by the latter in an upper support ring 93, threaded at 94 into the body 78, the inner sleeve 92 having a supporting collar 95 threaded thereon and engaged with the ring 93. At its lower end, the sleeve 92 receives in a seat 96 a lower support ring 97. Beneath the upper ring 93 is a stop ring 98 against which the uppermost Belleville spring 91 abuts at its inner periphery, the lowermost Belleville spring 91 abutting at its inner periphery with a thrust collar 99. As seen in FIG. 4, the thrust collar 99 has downwardly extending fingers 100 spaced circumferentially which entend through circumferentially spaced arcuate slots or openings 101 in the lower ring 97 into abutting contact with the upper end of the indexing guide 81. Upward movement of the indexing guide 81 from the position of FIG. 9 to the position of FIG. 10 causes corresponding upward movement of the thrust collar 99 and compression of the Belleville springs 91. The Belleville springs are preferred because they occupy a relatively small space as compared with conventional coiled compression springs and provide a high load spring which, as is well known, can have a constant spring rate. The Belleville springs 91, as best seen in FIGS. 3 and 7, are centralized or maintained in concentric relation with respect to one another without contacting either the outer housing 78 or the inner support sleeve 92 by means of outer peripheral centering rings 102 and inner peripheral centering rings 103. The stack of Belleville springs, as a whole, is centralized on the ring 98 and on the thrust collar 99, as seen in FIG. 2b. The centering ring 102 is radially split at 102a and the centering ring 103 is radially split at 103a, these rings being resiliently expansible to facilitate their application to the peripheries of the Belleville springs as well as to minimize constraint of the peripheral expansion which occurs as the frusto-conical springs are axially deformed. In addition, the inner periphery of each of the outer peripheral centering rings 102 is provided with a circumferentially extended groove 102b and the outer periphery of each of the inner peripheral centering rings 103 is provided with a corresponding groove 103b, these grooves 102b and 103b being generally V-shaped and affording clearance space enabling the contacting edges of the Belleville springs 91 to expand outwardly and inwardly, respectively, upon axial deflection, thereby minimizing friction and resultant hysteresis.

At the upper and lower inner edges of the outer centering ring 102 are retainer flanges 102c which project radially inwardly and retain the contacting peripheries of adjacent Belleville spring washers in assembled relation at their outer peripheries. Corresponding radial flanges 103c engage the inner peripheries of the Belleville springs to retain the same in assembled relation. Thus, the entire stack of Belleville springs can be installed as a unit over the upper end of the inner support member 92 before assembly of the stop ring 98 and the upper ring 93 in the support sleeve 92. The collar 95 can be threaded downwardly on the sleeve 92 to appropriately preload the Belleville spring assembly before it is installed in the housing 78 to overcome the hydrostatic pressure of fluid in the well bore annulus 13. The upper retainer rings 93 also clamps a lower flange 104 of a supporting sleeve 105 against the lower end of the housing section 63, this support sleeve 105 being connected at 106 to an upwardly extended member 107 which in turn is threadedly connected at 108 to the cylinder sleeve 61 which fixedly supports the cylinder sleeve 42 of the energizing section 15 previously described.

The annulus pressure responsive means 77 is adapted to apply an upward force to the indexing guide 81 to compress the Belleville springs 91 and shift the indexing guide 81 upwardly with respect to the ball cage 82 when the mandrel is to be allowed to move upwardly. Accordingly, within the body section 38 is a cylinder sleeve 110 having a sealing ring 111 at its upper end and a lower sealing ring 112 engaged within the body 38. This cylinder sleeve 110 has a suitable number of radial ports 113 communicating with an internal chamber 114 defined between the inner periphery of the cylinder sleeve 110 and the outer periphery of an annuluar differential piston 115 having an upper sealing ring 116 and a lower sealing ring 116' slideably engaged with the cylinder sleeve 110 to confine pressure fluid within the chamber 114. The inner periphery of the cylinder sleeve below the ports 113 is of a smaller diameter at 110a than the larger diameter 110b above the ports 113, and the differential piston 115 has complemental smaller and larger diameters which determine the differential pressure responsive area of the piston 115. Different size cylinder sleeve 110 and piston 115 sets can be utilized in the assembly depending upon the desired pressure response of the apparatus. The cylinder sleeve 110 is held against an upwardly facing shoulder 117 by a suitable spacer sleeve 118 which engages the upper end of the cylinder sleeve 110 and abuts with an upper retainer ring 119 snapped into the body section 38, facilitating substitution of different sizes of the cylinder sleeve 110 and the piston 115.

Disposed between the upper end of the piston 115 and fingers 83a which depend from the indexing guide 81 through slots 83b in the guide flange 83, is a thrust sleeve 120 by which the indexing guide 81 is forced upwardly when pressure fluid is applied to the differential piston chamber 114 to force the piston 115 upwardly. Here again, the fluid by which the piston 115 is pressurized is preferably a clean fluid, such as oil, rather than the usually dirty fluid in the well bore annulus 13. Accordingly, the body 38 has an annular cavity 121 covered by an annular bladder 122. The bladder 122 has an upper bead 123 clamped against the body 38 by a gage ring 124 and a lower bead 125 clamped against the body 38 by a lower gage ring 126. Suitable fill and bleed openings 127 and 128 are provided, whereby the chamber 121, the annular space 127 and the piston chamber 114 can be filled with clean oil. Extending between the gage rings 124 and 126 is a slotted protective sleeve 129. When the annulus 13 outside the shut-in valve assembly is pressurized, fluid in the chamber 121 will be displaced through ports 121a in the body 38 and from the chamber 127 through the ports 113 in the cylinder sleeve 110 into the piston chamber 114, forcing the piston 115, the thrust sleeve 120 and the indexing guide 81 upwardly from the position of FIG. 9 to the position of FIG. 10, thereby, as will now be described, allowing the mandrel 19 to move upwardly one increment of motion.

As best seen in FIGS. 9, 10, 11, the land 230 has an upwardly facing shoulder 230a and a downwardly facing shoulder 230b. The indexing guide 81 has an upper inner cylindrical surface 81a engageable with the balls 86, when the indexing sleeve is in its lowermost position, for holding the balls 86 in an inwardly displaced location engageable by the upwardly facing shoulder 230a, thereby preventing upward movement of the mandrel 19. Thus, the mandrel is held in its lowermost position, as seen in FIGS. 2a through 2c, with the valve passages 24 through 27 all closed. When by the application of annulus pressure to the piston 115, the piston and the indexing sleeve 81 are moved upwardly to the position of FIG. 10, the balls 86 are traversed by a clearance space or annular groove 186 in the inner periphery of the indexing guide 81 allowing the balls 86 to shift outwardly, releasing the mandrel 19 for upward movement under the influence of differential pressure across the lower end of the valve sleeve 22 and the upward bias of the energizing means 15, as previously described. The land 230 passes over the balls 86, but upward movement of the mandrel 19 is limited by engagement of an upper shoulder 240a on the land 240 with the balls 88 which are held in an inwardly displaced condition by a lower inner cylindrical surface 81b of the indexing guide 81. At this same time, the lower shoulder 230b of the land 230 prevents downward movement of the mandrel 19, since the balls 86 are held in the inwardly displaced position by an intermediate cylindrical surface 81c within the indexing guide 81. The lands 230 and 240 are spaced apart and correspondingly the balls 86 and 88 are spaced apart axially of the assembly a distance corresponding to the distance necessary for the mandrel 19 to travel upwardly to bring the valve sleeve ports 24 into communication with the valve body ports 30 in one increment of motion of the mandrel 19, further upward motion being prevented, as seen in FIG. 10, by engagement of the land shoulder 230a with the balls 88.

When annulus pressure is relieved, the Belleville springs 91 will force the indexing guide 81 downwardly until the balls 88 are again free for outward movement into an annular relief groove 188 within the indexing guide 81. The balls 86 are again held inwardly displaced by the indexing guide surface 81a, thereby allowing the mandrel 19 to move upwardly until the land shoulder 240a contacts the inwardly held balls 86. This latter increment of motion of the mandrel 19 is sufficient to move the sealing ring 28 below the valve sleeve ports 24 to a location above the valve body port 30 and will locate the cylindrical valve sleeve 22, with the body port 30 straddled by the sealing rings 28, below the sleeve port 24 and above the sleeve port 25, at which position the valve is again closed. This operation can be repeated until each of the additional lands 250, 260 and 270 have been moved upwardly to a stop position engaged by the balls 88 at which position the successive ports 25, 26 and 27 of the valve sleeve have been opened. Various numbers of lands on the mandrel and ports in the valve may be utilized, but in general, it has been found that in the typical drill stem testing of an oil or gas well the valve is not opened more than three or four times at the most. On the other hand, if more openings are desired, the above operations can be reversed and the mandrel can be forced downwardly by dropping a plug through the drill pipe string which will land on top of the mandrel, closing the choke 70, and can be pressurized through the drill pipe string to overcome formation pressure acting upwardly on the mandrel and force the mandrel back downwardly. Such a plug is well known in the oil well drilling and producing fields.

From the foregoing, it will now be apparent that the present invention provides a simple, efficient drill stem testing apparatus, including a novel shut-in valve aseembly which can be operated responsive to annulus pressure above the packer, so that the testing operation is independent of motion of a floating vessel from which the testing operation is being performed.

Claims

I claim:

1. Apparatus for performing a drill stem test in a well bore traversing an earth formation in which casing is set comprising: a test string adapted to be connected to a string of pipe and run into the well casing, said test string including a packer having anchor means and packing means expansible into anchoring and sealing engagement with said well casing above said earth formation to anchor said test string in said casing and separate said formation from the casing above said packer, test instrument means associated with said packer and in communication with said earth formation, and shut-in valve means above said packer for controlling the flow of fluid from said formation through said test string, said shut-in valve means including a body connected in said test string, said body having therein a tubular mandrel shiftable longitudinally of said body, valve means including a valve member carried by said mandrel and shiftable therewith to a plurality of successive open and closed positions for enabling and for shutting off the flow of fluid from said formation through said mandrel a plurality of times as said tubular mandrel is shifted longitudinally in one direction, and escapement control means responsive to the pressure of fluid in said well casing above said packer for controlling the progressive movement of said mandrel and said valve member in said one direction through said plurality of successive positions.

2. Apparatus as defined in claim 1, wherein said control means comprises escapement means on said mandrel and in said body.

3. Apparatus as defined in claim 1, wherein said control means comprises escapement means on said mandrel and in said body, including stops on said mandrel and detent means carried by said body and engageable with said stops, means responsive to said fluid in said well casing for releasing said detent means, and spring means normally biasing said detent means to a mandrel stopping position.

4. Apparatus as defined in claim 1, wherein said control means comprises escapement means on said mandrel and in said body, including stops on said mandrel and detent means carried by said body and engageable with said stops, means responsive to said fluid in said well casing for releasing said detent means, and spring means normally biasing said detent means to a mandrel stopping position, said spring means comprising a plurality of Belleville springs stacked in concentric relation in edge-to-edge peripheral engagement.

5. Apparatus as defined in claim 1, wherein said control means comprises escapement means on said mandrel and in said body, including stops on said mandrel and detent means carried bu said body and engageable with said stops, means responsive to said fluid in said well casing for releasing said detent means, and spring means normally biasing said detent means to a mandrel stopping position, said spring means comprising a plurality of Belleville springs stacked in concentric relation to edge-to-edge peripheral engagement, and adjustable means for preloading said springs.

6. Apparatus as defined in claim 1, wherein said mandrel is sealed in said body and exposed to the pressure of fluid in said formation to urge said mandrel through said positions.

7. Apparatus as defined in claim 1, wherein said mandrel is sealed in said body and exposed to the pressure of fluid in said formation to urge said mandrel through said positions, and including energizing means responsive to the pressure of fluid in said casing above said packer also urging said mandrel through said positions.

8. Apparatus as defined in claim 1, wherein said mandrel is sealed in said body and exposed to the pressure of fluid in said formation to urge said mandrel through said positions, and including energizing means responsive to the pressure of fluid in said casing above said packer also urging said mandrel through said positions, and means for dampening such movement of said mandrel.

9. Apparatus as defined in claim 1, wherein said control means comprises escapement means on said mandrel and in said body, including stops on said mandrel and detent means carried by said body and engageable with said stops, means responsive to said fluid in said well casing for releasing said detent means, and spring means normally biasing said detent means to a mandrel stopping position, and including energizing means responsive to the pressure of fluid in said casing above said packer for urging said mandrel through said positions when said detent means are released.

10. Apparatus as defined in claim 1, wherein said control means comprises escapement means on said mandrel and in said body, including stops on said mandrel and detent means carried by said body and engageable with said stops, means responsive to said fluid in said well casing for releasing said detent means, and spring means normally biasing said detent means to a mandrel stopping position, and including energizing means responsive to the pressure of fluid in said casing above said packer for urging said mandrel through said positions when said detent means are released, and means for dampening such movement of said mandrel.

11. A shut-in valve for use in performing drill stem tests in a well bore, comprising: an elongated tubular body, an elongated tubular mandrel axially shiftably disposed in said body, said body and said mandrel having valve means successively openable and closeable a plurality of times upon longitudinal movement in one direction of said mandrel relative to said body to enable and to prevent the flow of fluid through said mandrel, escapement means for controlling said longitudinal movement of said mandrel within said body and limiting said movement of said mandrel to successive positions at which said valve means is opened and closed, and fluid pressure operated means for operating said escapement means to enable successive movements of said mandrel in said body.

12. A shut-in valve as defined in claim 11, wherein said escapement means comprises successive stops on said mandrel and detent means carried by said body, said means for operating said escapement means including fluid pressure responsive means for releasing said detent means.

13. A shut-in valve as defined in claim 11, wherein said escapement means comprises successive stops on said mandrel and detent means carried by said body, said means for operating said escapement means including fluid pressure responsive means for releasing said detent means, and spring means normally biasing said detent means to a mandrel stopping position.

14. A shut-in valve as defined in claim 11, wherein said escapement means comprises successive stops on said mandrel and detent means carried by said body, said means for operating said escapement means including fluid pressure responsivve means for releasing said detent means, and spring means normally biasing said detent means to a mandrel stopping position, said spring means comprising a plurality of Belleville springs stacked in concentric relation in edge-to-edge peripheral engagement.

15. A shut-in valve as defined in claim 11, wherein said escapement means comprises successive stops on said mandrel and detent means carried by said body, said means for operating said escapement means including fluid pressure responsive means for releasing said detent means, and spring means normally biasing said detent means to a mandrel stopping position, said spring means comprising a plurality of Belleville springs stacked in concentric relation in edge-to-edge peripheral engagement, and adjustable means for preloading said springs.

16. A shut-in valve as defined in claim 11, wherein said fluid pressure operated means comprises differential piston and cylinder means in said body, and means including a bladder exposed externally of said body and confining a quantity of oil for actuating said piston means responsive to external pressure applied to said bladder.

17. A shut-in valve as defined in claim 11, wherein said fluid pressure operated means includes a cylinder sleeve in said body having differential internal diameters, an annular piston slideably engaged with said sleeve and defining therewith a pressure chamber, said piston having differential areas exposed to the pressure of fluid in said chamber.

18. A shut-in valve as defined in claim 11, wherein said fluid pressure operated means includes a cylinder sleeve in said body having differential diameters, an annular piston slideably engaged with said sleeve and defining therewith a pressure chamber, said piston having differential areas exposed to the pressure of fluid in said chamber, and means removably mounting said cylinder sleeve and said piston in said body.

19. A shut-in valve as defined in claim 11, wherein said mandrel is sealed in said body to be responsive to the pressure of fluid in said body to move said mandrel.

20. A shut-in valve as defined in claim 11, including energizing means for moving said body responsive to applied fluid pressure.

21. A shut-in valve as defined in claim 11, including energizing means for moving said body responsive to applied fluid pressure, said energizing means comprising an annular piston on said mandrel and a cylinder sleeve encircling said annular piston and defining with said mandrel a pressure chamber, and means for applying pressure to fluid in said chamber.

22. A shut-in valve as defined in claim 11, including energizing means for moving said body responsive to applied fluid pressure, said energizing means comprising an annular piston on said mandrel and a cylinder sleeve encircling said annular piston and defining with said mandrel a pressure chamber, and means for applying pressure to fluid in said chamber including a bladder exposed at the exterior of said body.

23. A shut-in valve as defined in claim 11, including energizing means for moving said body responsive to applied fluid pressure, said energizing means comprising an annular piston on said mandrel and a cylinder sleeve encircling said annular piston and defining with said mandrel a pressure chamber, and means for applying pressure to fluid in said chamber, and said body and said mandrel having cylinder and piston meanse for dampening movement of said mandrel.

24. A shut-in valve as defined in claim 11, wherein said escapement means comprises a plurality of circumferential lands spaced longitudinally of said mandrel and each having an upwardly facing stop shoulder, a ball cage surrounding said mandrel and having vertically spaced ball detents radially shiftably carried thereby, an axially shiftable indexing guide disposed about said ball cage and having internal axially spaced ball detent engaging surfaces and intermediate clearance spaces for receiving said ball detents, said fluid pressure operated means including means acting on said indexing guide to shift the latter axially in one direction, spring means acting on said indexing guide to force the latter axially in the other direction, said shoulders, said ball detents, said ball detent engaging surfaces and said relief spaces being axially spaced so that said ball detents alternately are held radially inwardly for engagement by one of said shoulders and are free to move radially outwardly upon axial movement of said indexing guide in opposite directions to open and close said valve means successively upon each increment of movement of said mandrel.

25. A shut-in valve as defined in claim 11, wherein said escapement means comprises a plurality of circumferential lands spaced longitudinally of said mandrel and each having an upwardly facing stop shoulder, a ball cage surrounding said mandrel and having vertically spaced ball detents radially shiftably carried thereby, an axially shiftable indexing guide disposed about said ball cage and having internal axially spaced ball detent engaging surfaces and intermediate clearance spaces for receiving said ball detents, said fluid pressure operated means including means acting on said indexing guide to shift the latter axially in one direction, spring means acting on said indexing guide to force the latter axially in the other direction, said shoulders, said ball detents, said ball detent engaging surfaces and said relief spaces being axially spaced so that said ball detents alternately are held radially inwardly for engagement by one of said shoulders and are free to move radially outwardly upon axial movement of said indexing guide in opposite directions to open and close said valve means successively upon each increment of movement of said mandrel, said fluid pressure operated means further including a cylinder sleeve in said body having differential internal diameters, an annular piston slideably engaged with said sleeve and defining therewith a pressure chamber, said piston having differential areas exposed to the pressure of fluid in said chamber, and means removably mounting said cylinder sleeve and said piston in said body.

26. A shut-in valve as defined in claim 11, wherein said escapement means comprises a plurality of circumferential lands spaced longitudinally of said mandrel and each having an upwardly facing stop shoulder, a ball cage surrounding said mandrel and having vertically spaced ball detents radially shiftably carried thereby, an axially shiftable indexing guide disposed about said ball cage and having internal axially spaced ball detent engaging surfaces and intermediate clearance spaces for receiving said ball detents, said fluid pressure operated means including means acting on said indexing guide to shift the latter axially in one direction, spring means acting on said indexing guide to force the latter axially in the other direction, said shoulders, said ball detents, said ball detent engaging surfaces and said relief spaces being axially spaced so that said ball detents alternately are held radially inwardly for engagement by one of said shoulders and are free to move radially outwardly upon axial movement of said indexing guide in opposite directions to open and close said valve means successively upon each increment of movement of said mandrel, said fluid pressure operated means further including a cylinder sleeve in said body having differential internal diameters, an annular piston slideably engaged with said sleeve and defining therewith a pressure chamber, said piston having differential areas exposed to the pressure of fluid in said chamber, and means removably mounting said cylinder sleeve and said piston in said body, said mandrel and said body having means defining an energizing piston chamber, and said mandrel having a piston area exposed to the pressure of fluid in said energizing piston chamber to move said mandrel longitudinally as aforesaid.

27. A shut-in valve as defined in claim 11, wherein said escapement means comprises a plurality of circumferential lands spaced longitudinally of said mandrel and each having an upwardly facing stop shoulder, a ball cage surrounding said mandrel and having vertically spaced ball detents radially shiftably carried thereby, an axially shiftable indexing guide disposed about said ball cage and having internal axially spaced ball detent engaging surfaces and intermediate clearance spaces for receiving said ball detents, said fluid pressure operated means including means acting on said indexing guide to shift the latter axially in one direction, spring means action on said indexing guide to force the latter axially in the other direction, said shoulders, said ball detents, said ball detent engaging surfaces and said relief spaces being axially spaced so that said ball detents alternately are held radially inwardly for engagement by one of said shoulders and are free to move radially outwardly upon axial movement of said indexing guide in opposite directions to open and close said valve means successively upon each increment of movement of said mandrel, said fluid pressure operated means further including a cylinder sleeve in said body having differential internal diameters, an annular piston slideably engaged with said sleeve and defining therewith a pressure chamber, said piston having differential areas exposed to the pressure of fluid in said chamber, and means removably mounting said cylinder sleeve and said piston in said body, said mandrel and said body having means defining an energizing piston chamber, and said mandrel having a piston area exposed to the pressure of fluid in said energizing piston chamber to move said mandrel longitudinally as aforesaid, said pressure chamber of said fluid pressure operated means and said energizing piston chamber being filled with oil and including bladders exposed externally of said body and confining said oil in said chamber.

28. A shut-in valve as defined in claim 11, wherein said mandrel is sealed in said body to be responsive to the pressure of fluid in said body to move said mandrel, and said escapement means normally limits movement of said mandrel to a position at which said valve means is closed.