US3207221A - Automatic blow-out preventor means - Google Patents

Description

Se t. 21, 1965 c. B. COCHRAN ETAL AUTOMATIC BLOW-OUT PREVENTOR MEANS 6 Sheets-Sheet 1 Filed March 21, 1963 CHUDL E I6 8. L Off/KAN JAMES D. M 077- J. E. EDWARDS JR.

INVENTOR.

ATTORNEY P 1965 c. B. COCHRAN ETAL 3,207,221

AUTOMATIC BLOW-OUT PREVENTOR MEANS 6 Sheets-Sheet 2 Filed March 21, 1965 4M m N 7/ Mr 5 x P k m imam": e a a ammm .IE 3 u H .E 7 a a p Aim l zzfi. V w .m 6%mm m IIILIE 9 4 4 J 2 Z nATTORNE Y p 21, 1965 c. B. COCHRAN ETAL 3,207,221

AUTOMATIC BLOW-OUT PREVENTOR MEANS Filed March 21, 1963 6 Sheets-Sheet 3 B.COCHRWV MES 0 ATTORNEY Sept. 21, 1965 C. B. COCHRAN ETAL AUTOMATIC BLOW-OUT PREVENTOR MEANS 6 Sheets-Sheet 4 Filed March 21, 1963 J. E. EDWIODi JR.

4 INA? cl/wu/a/ flax/{RAN JAMES D. MOTTp 21, 1955 c. B. COCHRAN ETAL 3,207,221

AUTOMATIC BLOW-OUT PREVENTOR MEANS 6 Sheets-Sheet 5 Filed March 21, 1963p 21, 1965 c. B. COCHRAN ETAL 3,207,221

AUTOMATIC BLOW-OUT PREVENTOR MEANS 6 Sheets-Sheet 6 Filed March 21, 1963 N w a 52 M50 M 1 B m 0mm 5. L E 0 0 J a d" Pv w \v Z 1. m

wrmmw mm United States Patent 3,207,221 AUTOMATIC BLOW-OUT PREVENTOR MEANS Chudleigh B. Cochran, James I). Mott, and Joseph E.

Edwards, Jr., Houston, Tex., assignors, by mesne assignments, to Brown Oil Tools, Inc., Houston, Tex., a corporation of Texas Filed Mar. 21, 1963, Ser. No. 266,960 9 Claims. (Cl. 166-85) This invention relates to automatic blow-out preventors for well pipes and more particularly to automatic stripper-type blow-out preventors.

In the operation of oil and gas wells, it is frequently necessary to run pipe strings, usually tubing strings, into and out of the well bores, while the well is under high fluid pressure. Various blow-out prevent-or means are conventionally employed to control the pressure while the pipe is being run. In one common system two or more conventional ram-type preventors are installed in spaced-apart relation on the wellhead to confine the pressure between the tubing and easing. At least two preventors are necessary because the tubing string being run is ordinarily made up of sections joined by collars larger in external diameter than the tubing sections. Since the collars cannot be passed through the rams while they are closed about the tubing, the rams must be worked alternately, releasing one to allow a collar to pass through while the other is confining the pressure in the annulus between the tubing and the casing. This operation is timeconsuming and can be hazardous because of the possibility that both preventors may accidentally be opened at the same time, resulting in a blow-out or other condition dangerous to the well personnel.

In another conventional system, stripper-type seals are employed. In this system, unlike the ram-type systems, the seals are not opened and closed about the tubing, but are continuous flexible bodies, usually having lip-type flanges which maintain continuous sealing engagement about the tubing by virtue of the well pressure exerted against the sealing flanges. In such systems, the seals are necessarily under the well pressure at all times, and passage of enlargements on the tubing, such as the collars, is eifected by forcibly moving the collars through the strippers, the resiliency of the strippers being depended upon to yield sufiiciently to permit passage of the collars. However, such strippers necessarily have a quite short life due to the excessive wear occasioned by the forcing of the tubing enlargements through the pressureloaded seal elements. In some cases, the destructive wear is so great that the strippers will not last out the running of a string of pipe of even moderate length, requiring shut-down of the operation to replace the strippers.

Accordingly, it is a primary object of this invention to provide blow-out preventor systems for use in running pipe strings which avoid the difficulties and disadvantages of the more conventional systems such as are enumerated above.

A principal object is to provide a blow-out preventor system employing a pair of seal elements in combination with sensing means responsive to enlargements on the tubing string being run in a well and cooperating with fluid-pressure-actuated operating means to automatically actuate the seal elements alternately to confine the annulus pressure between the casing and tubing, while contemporaneously automatically equalizing the pressure across the non-actuated seal elements in the advance of passage therethrough of the enlargement.

Another object is to provide a blow-out preventor sys-' tem of the character described wherein the seal elements may be either ram-type or stripper-type, and wherein the operating means is hydraulically actuated.

In accordance with one embodiment of this invention, a structure is provided which includes a pair of longitudinally spaced stripper elements comprising resilient seal members adapted to sealingly engage a tubing string or other pipe which is being run into a well and to seal thereabout when subjected to the annulus pressure between the pipe string being run and the well casing. Associated with the strippers are sensing elements which are responsive to the passage of enlargements on the pipe or tubing string and which are operatively associated with operating means actuated by fluid pressure to alternately actuate one of the stripper elements to confine the fluid pressure while equalizing the pressure across the other stripper element in advance of the passage of the enlargement through the stripper element. The alternate actuation of the stripper elements is efiected automatically by means of the sensing elements so that no manual manipulations are required to make sure that an enlargement on the pipe or tubing string being run will not be caused to pass through a stripper element which is under pressure. At the same time, the other of the stripper elements will be under pressure sufficient to maintain the necessary seal between the tubing string and the casing.

In another embodiment in accordance with this invention, the seal elements are of the conventional ram-type which are automatically actuated in the same manner and by the same enlargement-sensing and actuating elements as are used for the stripper-type embodiment.

In yet another embodiment a somewhat modified hydraulic device is employed for operating the seal elements in response to actuation by the enlargement-sensing elements.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates a useful embodiment in accordance with this invention.

In the drawing:

FIG. 1 is a view partly in section and partly diagrammatic illustrating a stripper blow-out preventor system in accordance with this invention;

FIGS. 2 and 3 are generally diagrammatic views illustrating successive stages in the operation of the device while a tubing string is being run into a well;

FIGS. 4 and 5 are diagrammatic views similar to FIGS. 2 and 3 illustrating the positions of the parts when a tubing string is being pulled from a well;

FIG. 6 is a cross-sectional view taken generally alongline 66 of FIG. 1;

FIG. 7 is a cross-sectional view alongline 7--7 of FIG. 1;

FIG. 8 is a perspective view of one of the control elements employed in the system;

FIGS. 9 and 10 are generally diagrammatic views generally similar to FIGS. 2 and 3 but substituting ram-type seal elements for the stripper-type elements;

FIG. 11 is a cross-sectional view taken generally along line 1111 of FIG. 10; and

FIGS. 12 and 13 are views generally similar to FIGS. 2

and 3, but illustrating a modified form of hydraulic actuating system for the seal elements.

Referring first to FIGS. 1 to 8 of the drawing, the blowout preventor structure comprises a generally tubular housing, designated generally by the letter H, adapted to be mounted on a wellhead fitting P, which may be of any suitable type permitting the preventor housing H to be suitably supported in coaxial alignment with the bore of a well (not shown) but which, it will be understood, will be lined with the usual well casing (not shown). The housing structure is designed to receive a string of pipe P which may be run into, or pulled from, the well through the bore of housing H.

Pipe P, which may be a string of well tubing, comprises a plurality of pipe sections connected by collars C which form longitudinally spaced external enlargements about the pipe string.

Housing H is made up of a plurality of coaxial end-toend connected, generally tubular members which include upper and lower stripper seal units S and S respectively, an upper enlargement-sensing unit E connected to the upper end of upper stripper seal unit S and a lower sensing unit E connected between the stripper units.

Stripper units S and S are substantially identical in construction, each comprising a metallictubular body 10 and atubular sealing element 11 concentrically mounted in the bore ofbody 10.Sealing element 11 is constructed of a generally conventional flexible resilient composition and has an inwardly projectingannular sealing portion 12 adapted to normally have slidable sealing contact with the exterior of pipe P. The ends of sealingelement 11 are secured to metal upper and lower end rings 13 and 14, respectively.Upper end ring 13 has an external downwardly facingshoulder 15 engageable on an internal upwardly facingshoulder 16 in the bore ofbody 10.Lower end ring 14 seats against an upwardly facing internal shoulder 17 inbody 10. Alock pin 18 is screwed through the wall ofbody 10 into arecess 19 in the lower end ring. The shouldered engagement betweenupper end ring 13 andbody 10 and the cooperation betweenlower end ring 14, shoulder 17 andlock pin 18 serve to lock the end rings tobody 10, holding them stationary while permittingseal elements 11 to radially expand and contract, as will appear hereinafter. The inner wall ofbody 10 opposite sealingelement 11 is recessed to provide theannular chamber 20. One or moreradial openings 21 are provided throughlower end ring 14 to provide fluid pressure communication between chamber and the annular space A defined between housing H and pipe P. It will be understood that annular space A is in communication with the well annulus (not shown), that is, the annular space between pipe P and the wall of the well into or out of which the pipe is being run.

The lower end ofbody 10 of lower stripper unit S is provided with a threadedpin 22 by means of which housing H is threadedly secured to wellhead fitting F.

Upper and lower enlargement-sensing units E and E are also substantially identical in construction. Each includes a mountingcollar 25 which forms a part of housing H and also functions to support the operative elements of the sensing unit. The upper mounting collar connects aguide nipple 26, which forms the uppermost element of housing H, in axially spaced relation to the upper end ofbody 10 of the upper stripper unit, thereby providing theannular space 27 therebetween.

Lower mountingcollar 25 connectsbodies 10 of the upper and lower stripper units in axially spaced relation to provide theannular space 28 therebetween.

The operative elements of the sensing units include a plurality ofcontact pads 30 mounted for limited radial movement inspaces 27 and 28. The contact pads are conveniently constructed as segments of a ring (FIG. 6) arranged to surround pipe P and may be formed with forwardly projectingportions 31 on their inner surfaces to provide the pipe contacting points. Any desired number ofpads 30 may be employed. Three are shown in the illustrative embodiment. The top and bottom walls ofspaces 27 and 28 are provided withopposed keeper lips 32 and 33, respectively, which are adapted to cooperate with oppositely extending flanges 34-34 at the rearward edges of the pads to confine the pads withinspaces 27 and 28 while permitting limited radial movement of the pads sufficient to projectportions 31 into contact with pipe P.

Each of thepads 30 is urged outwardly ofspaces 27 and 28 toward pipe P by identical structures, each of which includes ahollow plunger 35 which extends radially through the mounting collar and is slidable therein.Plunger 35 has its inner end received in asocket 36 in the outer surface ofpad 30 and its outer end enclosed by acylinder 37 which is screwed into the exterior of the mounting collar. The outer end ofcylinder 37 is closed by acap 38 having asocket 39 to slidably receive the outer end ofplunger 35. Acoil spring 40 is mounted insocket 39 in compression between the end of the plunger and the bottom of thesocket 30 toward pipe P.

Plunger 35 carries a sealedpiston 41 slidable incylinder 37 with the plunger and defining apressure chamber 42 between the piston andcap 38.Pressure chamber 42 is adapted to contain a body of a suitable pressure fluid. Aconduit 43 provides pressure fluid communication betweenchamber 42 and an annularpressure fluid reservoir 44 formed within the body of mountingcollar 25. As the pressure fluid system which includesplunger 35 is a closed system, one of theseveral conduits 43 may be connected to asmall accumulator 45 to accommodate excessive displacement of fluid in the pressure fluid system during operation of the device. Apipe 46 leads fromconduit 43 of the upper sensing unit E to one of theinlet ports 48 of a four-way valve 47, of generally conventional rotary construction, having a ported plug 470. Apipe 46a leads fromconduit 43 of lower sensing unit E to anotherinlet port 48a ofvalve 47.

Aconduit 49 leads from one of thedischarge ports 50 ofvalve 47 to one end of control valve, designated generally by the letter V, and asecond conduit 51 leads from the other discharge port 5011 ofvalve 47 to the opposite end of control valve V. In one .position ofplug 47a (FIGS. 1, 2 and 3)conduits 46 and 46a are placed in communication withconduits 49 and 51, respectively. In a second position ofplug 47a (FIGS. 4 and 5),conduits 46 and 4611 are put in communication withconduits 51 and 49, respectively.

Control valve V constitutes a portion of a second closed fluid pressure system, referred to herein as the actuating system, which is adapted to actuatestrippers 11 alternately in response to actuating signals received from the sensing units. The actuating system controls apressure equalizing conduit 55, the opposite ends of which communicate throughports 56 inbodies 10 withpressure chambers 20 of the stripper units S and S A generally conventional three-way rotary valve 57 (shown in perspective in FIG. 8) is mounted inconduit 55 and includes :acasing 58 having threeports 58a, 58b and 580, two of which, 58a and 581:, are in communication with branches ofconduit 55. Port 580 communicates with ableed conduit 59. Aplug member 60 is rotatably mounted incasing 58 and is adapted to oscillate between two positions for selectively placing chambers 20-20 in communication with each other or onlyupper chamber 20 withbleed conduit 59.Plug member 60 is driven by means of ashaft 61 connected to avane motor 62 which is mounted in acasing 63 and is caused to oscillate by fluid pressure directed intocasing 63 through one or the other of a pair of inlet ports 64 and 65 which are in communication withpressure fluid conduits 66 and 67, respectively, which lead from control valve V.

Control valve V is a generally conventional multi-port spool-type valve comprising a tubular casing 70 and a spool-type valve member 71 slid-able axially in the case 5 ing.Valve member 71 is formed with a pair of enlarge ments 7272 at its opposite ends and a third enlargement 73 intermediate the end enlargements, the several enlargements having slidable sealing engagement with the wall of casing 70. The three enlargements define between them a pair ofannular passageways 74 and 75 which communicate, respectively, withoutlet ports 76 and 77 at all positions of the spool member.Outlet ports 76 and 77 communicate withpressure fluid conduits 66 and 67, respectively. A pair of longitudinally spacedvent ports 78 and 79 are provided through the wall of casing 70 and are longitudinally spaced so that only one of them will be in communication with one of thepassageways 74 and 75 at any position ofvalve member 71. Thus, whenvalve member 71 is in the position shown in FIGS. 1 and 2,passageway 75 will be in communication withvent port 79, whilepassageway 74 will be cut off fromvent port 78 by anend enlargement 72. Whenvalve member 71 has been shifted to the opposite end of casing 70 (FIG. 3),passageway 74 will be in communication withvent port 78 whilepassageway 75 will be cut off from communication withvent port 79.Vent ports 78 and 79 are connected to acommon header 80 which leads to a pressurefluid accumulator tank 81.

Aninlet port 82 communicates with valve casing 70 at substantially the mid-point thereof, being located to communicate with one or the other ofpassageways 74 and 75, depending upon the position ofvalve member 71.Inlet port 82 is connected to apipe 83 which leads totank 81 and has apump 84 positioned therein to deliver fluid under pressure to valve V throughinlet port 82.

Mounted on the opposite ends of valve casing 70 arepressure cylinders 85 and 86 in which are disposedpistons 87 and 88, respectively, mounted onrods 89 and 90, respectively, which slidably project through the end walls of casing 70 into engagement with the opposite ends ofvalve member 71.Pistons 89 and 90 are biased outwardly with respect to ends of casing 70 by means of the springs 91.Cylinder 85 is in communication withconduit 49 andcylinder 86 withconduit 51, the cylinders thereby forming part of the closed pressure systems which include sensing elements E and E The blow-out preventor is operated in the following manner: As seen in FIG. 1, pipe string P is in process of being run into a well through the blow-out preventor structure herein described. At the stage shown, collar has movedopposite pads 30 of the upper sensing element E and has forced the pads rearwardly against the pressure ofsprings 40, thereby movingpistons 41 rearwardly and displacing pressure fluid fromchambers 42 throughconduits 43 intoreservoir 44. Some of the displaced fluid will be forced throughconduit 46 and throughmultiport valve 47 viaports 48 and 50 intoconduit 49 which will deliver the displaced pressure fluid intocylinder 85. The pressure fluid will act onpiston 87, drivingvalve member 71 to the position shown in FIG. 1. This will place pressurefluid supply conduit 83 into communication withpassageway 74 whilepassageway 75 is placed in communication withvent port 79. The pressure fluid will flow throughpassage 74 and thence throughports 76 andconduit 66 against one side ofvane motor 62, which will rotate plug 60 ofvalve 57 to the position shown in FIG. 1. The fluid in the other side of the vane motor will drain back throughconduit 67,valve passageway 75 andmanifold 80 to thestorage tank 81. This movement ofvalve 57, as shown, will permitpressure chamber 20 of upper stripper unit to be vented throughconduit 55 to bleedpipe 59 and will equalize the pressure inchamber 20 of upper stripper unit S with the atmosphere. At the same time, withvalve plug 60 in the position shown in FIG. 1,conduit 55 will be cut ofif frompressure chamber 20 of the lower stripper unit S which will then be under the pressure of the well fluid in annulus A. As a result,stripper element 11 of the lower stripper unit 8,, will be actuated to form a fluid-tight seal about pipe P, thereby confining the annulus pressure at this point while the upper stripper unit is relieved of the well pressure throughbleed pipe 59. As the pipe string moves downwardly, therefore,stripper element 11 of upper stripper unit S will relax, allowing collar C to pass through easily and without damage to the stripper element. FIG. 2 illustrates, diagrammatically, the positions of the several parts :at the stage of operations just described, at which collar C has passed the upper sensing unit and is passing through the upper stripper unit S As the pipe string continues to move down and collar C passes the sensing pads of lower sensing unit E the latter is activated to displace pressure fluid throughconduits 43, 46a and 51 intocylinder 86, movingpiston 88 in a direction to drivevalve member 71 to the opposite end of casing 70, as seen in FIG. 3. When this occurs,passageway 75 will be placed into communication with pressure fluid fromconduit 83 whilepassageway 74 is connected to vent passage '78. The pressure fluid will be transmitted throughconduit 67 to the other side ofvane motor 62, rotatingplug 60 ofvalve 57 to the position shown in FIG. 3, at whichpressure chambers 20 of both stripper units S and S will be placed into communication with each other, applying annulus pressure to upper stripper unit S and thereby actuating the sealing element of the upper stripper unit to close the annulus between pipe P and housing H, while passing throughport 21 and equalizing the pressure across the lower stripper unit. This will relieve the latter from the pressure load so that collar C may pass through thelower stripper element 11 without exerting any serious drag or destructive force thereon. When the next collar reaches sensing unit E the operations will be repeated, that is, lower stripper S will be actuated to seal the well annulus about pipe P, while the pressure across the upper stripper unit is equalized with the atmosphere, freeing it for ready passage of the next collar.

To pull the string of pipe from the well under pressure, the only change required is to rotateplug 47a ofvalve 47 to the position shown in FIGS. 4 and 5. In this position,conduit 46a will be placed into communication withconduit 49 andconduit 51 will be placed into communication withconduit 46, and all other connections will be exactly as shown in FIGS. 1 to 3 and as previously described.

It will be assumed that collar C in FIG. 4 will have passed through lower stripper unit S while the latter is under equalized pressure, as this was the case in order for the collar to have moved downwardly through the stripper initially. As collar C moves upwardly opposite the pads of lower sensing unit E the latter will be actuated to displace pressure fluid throughconduits 46a and 49 by way ofvalve plug 47a tocylinder 85, movingvalve member 71 again to the position shown in FIG. 4, which is exactly the same position as in FIGS 1. and 2. In this position, the pressure fluid fromtank 81 will be delivered fromconduit 66 tovane motor 62, movingplug 60 to aposition placing conduit 55 in communication withbleed pipe 59, while cutting off communication to lowerpressure chamber 20. Whereupon, the lower stripper unit S will be actuated by the annulus pressure to seal otT the well annulus while the pressure across upper stripper unit S will be equalized with the atmosphere throughbleed conduit 59. Thereupon, when the pipe string is pulled upwardly, collar C will pass through the upper stripper element, which will have been unloaded of its pressure and upon-contacting the pads of upper sensing unit E as shown in FIG. 5, the pressure fluid displaced thereby throughconduit 46 andconduit 51 viaplug 47a ofvalve 47 will entercylinder 86 and act onpiston 88, movingvalve member 71 to the opposite position, shown in FIG. 5. Thereupon, pressure fluid fromconduit 83 will flow throughpassageway 75 viaconduit 67 to the other side of thevane motor 62, movingplug 60 ofvalve 57 to the position shown in FIG. 5, whereby the annulus pressure will be communicated to the upper stripper unit S to actuate the stripper element therein to seal off the annulus between pipe P and housing H, while equalizing the pressure across the lower stripper unit S in advance of the entry therein of the next collar on the pipe string. These operations will be repeated as each collar approaches each of the stripper units until the string of pipe has been withdrawn from the well.

In the foregoing description, the sensing units and the control elements are described as being actuated by means of a hydraulic pressure fluid. It will be readily evident, however, that one or both the sensing units and the control unit may be actuated with pneumatic pressure fluid. While this will require the use of pneumatic systems involving pilot valves and other conventional pneumatic equipment, the changes necessary to convert to use of a pneumatic fluid will be readily evident to those skilled in the art, and will involve no significant modifications of the invention herein disclosed.

It will be evident that in accordance with this invention a novel system is provided whereby two strippertype units may be employed as the blow-out preventors and are automatically operated to permit passage of enlargements on a pipe string when the pressure load is removed from one of the stripper units, the other being simultaneously actuated to seal off the annulus between the pipe string being run through the Well bore and the wall of the well bore.

FIGS. 9, and 11 illustrate a modification in which conventional ram-type sealing units, designated generally by the letters R and R are substituted for the corresponding stripper-type units of the previously described embodiment. Each of the ram-type blow-out preventor units R and R includes acasing 92 adapted for mounting transversely in housing H. A pair ofopposed rams 93 are slidably mounted incasing 92 to seal off the annular space between pipe string P and housing H when the rams are advanced to engage about the pipe string. The rams are operated by means ofpistons 94 secured to the outer ends of the rams and working incylinders 95 formed in the outer ends ofcasing 92.Springs 96 normally bias the rams to the retracted position. Pressure fluid is supplied tocylinders 95 through aheader 97 which, in unit R communicates withconduit 66, and in the case of unit R withconduit 67.

Since rams R and R constitute positive-type seals, the pressure equalizingconnections comprising ports 56 andconduit 55 may be eliminated, together withrotary valve 57 andvane motor 62. Instead,conduits 66 and 67 are connected directly, as noted, toheaders 97 of rams R and R respectively. I

With this arrangement, it 'will be seen that when upper sensing unit E is actuated by an enlargement, valve V will be actuated in exactly the same manner as previously described to deliver pressure fluid throughconduit 67 to lower ram unit R closing the latter about pipe P. This movement places upper ram unit R in communication throughpipe 66 withreturn pipe 80 leading to theaccumulator tank 81. The biasingspring 97 will cause retraction oframs 93 of ram unit R and thereby opens the seal to the passage of the enlargement.

When the enlargement engages the sensing element of sensing unit E value V will be actuated, as previously described, to placeconduit 66 in pressure communication with the pressure fluid supply, closing upper ram unit R about pipe P above the enlargement. At the same time, the pressure on the rams of ram unit R will be relieved, allowing the latter to open for subsequent passage of the enlargement.

In pulling pipe, it will only be necessary to reversevalve 47, as previously described, the operation being otherwise exactly just as described.

FIGS. 12 and 13 illustrate still another modification, and in this modification, stripper units 8;, and S corresponding to stripper units S and S respectively, are employed. The enlargement-sensing units E and E are identical to those previously described. Pressure equalizingconduit 55 connectingports 56 throughvalve 57 .are employed in this embodiment exactly the same as in the first described embodiment. Thevane motor 62 is likewise employed for operatingvalve 57, as ismultiport valve 47. However, instead of the external source of pressure fluid, such astank 81 and pump 84, and the multiport valve corresponding to valve V of the previously described embodiment, there is substituted a dual closed hydraulic system arrangement for operatingvane motor 62. In this embodiment,conduit 46, which leads from upper sensing unit E connects to port 48 ofvalve 47 and thence viaports 50 to one end of acylinder 100, the other end of which is connected, by means of aconduit 101, to one side ofvane motor 62.Conduit 46a is similarly connected toport 48a ofvalve 47 .and thence viaport 50a toconduit 51, which leads to one end of a secondidentical cylinder 100, the other end of which is connected by aconduit 101 to the other side ofvane motor 62. Each cylinder is divided intermediate its ends by apartition 102 having a central opening adapted to slidably receive a piston rod 103. The latter carries anupper piston 104 reciprocable in the portion ofcylinder 100 on one side ofpartition 102, and alower piston 105 reciprocable in the portion ofcylinder 100 on the opposite side ofpartition 102. In each cylinder theupper piston 104 is biased away frompartition 102 by means of acoil spring 106. The portion ofcylinders 100 betweenlower pistons 105 andconduit 101 contain bodies ofhydraulic fluid 107 which are adapted to flow back and forth throughconduits 101 between the related sides ofvane motor 62 and the communicating portions of therelated cylinders 100. Thus, two closed hydraulic systems are provided, each including one side ofvane motor 62 and the connected portion of therelated cylinder 100. It will be seen that when one of the pistons is moved in the direction to compress the body offluid 107,vane motor 62 will swing in one direction, while the body offluid 107 in the other side of the vane motor will be forced back into theother cylinder 100, moving thepistons therein to the retracted position. When the pressure forces are reversed, the vane motor is swung in the opposite direction.

In operation: When upper sensing unit E is actuated by passage of a collar C, fluid pressure will be exerted throughconduit 46 andports 48 and 50 invalve 47, and thence throughconduit 49 againstpiston 104 in the righthand one ofcylinders 100. The piston will be forced downwardly (as viewed in the drawing), forcing the body ofhydraulic fluid 107 therein to act upon the side ofvane motor 62 which will move plug 60 invalve 57 to the position shown in FIG. 12, in which lower seal unit 8.; will be held under pressure, sealing off about pipe P. The annular space between the sealing units will be relieved throughbleed pipe 59, thereby equalizing the pressure across the seal unit S As collar C engages lower sensing unit E after passing through upper seal unit S the piston in the left hand one of thecylinders 100 will be forced downwardly, causingvane motor 62 to swing in the opposite direction and movingvalve 57 to the position shown in FIG. 13, wherein pressure is equalized across lower seal unit S while the annulus pressure is transmitted between the seal units to actuate the upper seal unit S to seal about pipe P'af ter collar C has passed therethrough.

As in the previously described embodiments, when the pipe 1 s being pulled from the well the only change necessary 1n the structure shown in FIGS. 12 and 13, is to change the position ofvalve 47 to connectpipe 49 topipe 46a andconduit 46.

From the foregoing it will be seen that in each embodiment when running pipe into the well, the second or lower of the two sealing units is actuated first to seal off about the pipe and equalize the pressure across the first or 9 upper sealing unit. The first or upper sealing unit is actuated second in order to seal off about the pipe after the enlargement has passed it and thereby equalize the pressure across the second or lower of the two sealing units.

When pulling pipe from the well, positions of the seal units in order of their actuation is reversed. The upper seal unit becomes the second in order of passage by the enlargement but is actuated first, while the lower seal unit becomes the first in order of passage by the enlargement but is actuated second.

It will be evident, therefore, that the means employed to actuate the seal elements are arranged to successively actuate the seal elements in inverse order with respect to the direction of movement of the enlargement whereby to automatically equalize the pressure across each seal element as it is approached by the enlargement.

It will be understood that numerous changes and alterations may be made in the details of the illustrative embodiment within the scope of the appended claims but without departing from the spirit of this invention.

What we claim and desire to secure by Letters Patent is:

1. Automatic blow-out preventor means for use when running pipe strings into and out of a well under pressure, comprising a tubular housing mountable on a well head fitting and through which a pipe string is passed, spaced apart upper and lower contractible and expandible seal elements mounted in the housing actuatable to seal off the annular space between the housing and the pipe string, an enlargement-sensing means mounted in the housing adjacent each of the respective seal elements including fluid pressure signal-transmitting means operable to provide signals indicating the approach of an enlargement on the pipe string successively toward the respective seal elements, fluid pressure-operated means operably connected to said signal-transmitting means actuatable in response to said signals and arranged to successively actuate said seal elements in inverse order with respect to the direction of movement of said enlargement, whereby to automatically contract each seal element as it is approached by said enlargement.

2. Automatic blow-out preventor means according to claim 1, wherein said seal elements comprise radially movable segmental rams.

3. Automatic blow-out preventor means according to claim 1, wherein said seal elements comprise annular resilient stripper-type units.

4. Automatic blow-out preventor means according to claim 1 wherein said enlargement-sensing means comprises contactor elements radially movably mounted in said housing, means resiliently biasing said contactor means into maintained slidable engagement with the exterior of said pipe string whereby passage of an enlargement will efiect retractive movement of said contactor elements.

5. Automatic stripper-type blow-out preventor means for use when running pipe strings into and out of a Well under pressure, comprising, a tubular stripper housing mountable on a well head fitting and through which a pipe string is passed, spaced apart upper and lower annular resilient stripper seal elements mounted in the housing for engagement about the pipe string and actuatable by well pressure to seal off the annular space between the pipe string and the housing, conduit means providing well pressure communication between a point in said housing below the lower seal element and a point in said housing between said seal elements, multi-port valve means in said conduit means movable between a first position opening communication between said points and a second position closing ofl said communication while communicating only said point between said seal elements with the atmosphere, an enlargement-sensing means mounted in the housing at a point adjacent each of the respective seal elements operable to provide signals indicating the approach of an 10 enlargement on the pipe string successively toward the respective seal elements, fluid pressure signal-transmitting means operable by said sensing means, fluid pressureoperated means actuatable in response to said signals to successively move said valve means to said first and second positions, whereby to successively equalize the pressure across each seal element as it is approached by said enlargement while simultaneously directing well pressure to the other seal element to actuate the latter to seal off the annular space between the pipe string and the housing.

6. Automatic stripper-type blow-out preventor means according to claim 5 wherein said enlargement-sensing means comprises contactor elements radially movably mounted in said housing, means resiliently biasing said contactor means into maintained slidable engagement with the exterior of said pipe string whereby passage of an enlargement on the pipe string will efiect retractive move ment of said contactor elements.

7. Automatic stripper-type blow-out preventor means according to claim 5 wherein said enlargement-sensing means comprises contactor elements radially movably mounted in said housing, means resiliently biasing said contactor means into maintained slidable engagement with the exterior of said pipe string whereby passage of an enlargement on the pipe string will effect retractive movement of said contactor elements, and wherein said signaltransmitting means is actuatable by said retractive movement to transmit said signals for moving said valve means.

8. Automatic stripper-type blow-out preventor means for use when running pipe strings into and out of a well under pressure, comprising, a tubular stripper housing mountable on a well head fitting and through which a pipe string is passed, spaced apart upper and lower annular resilient stripper seal elements mounted in the housing for engagement about the pipe string and actuatable by well pressure to seal off the annular space between the pipe string and the housing, conduit means providing well pressure communication between a point in said housing below the lower seal element and a point in said housing between said seal elements, multi-port valve means in said conduit means movable between a first position opening communication between said points and a second position closing off said communication while communicating only said point between said seal elements with the atmosphere, an enlargement-sensing means mounted in the housing at a point adjacent each of the respective seal elements operable to provide signals indicating the approach of an enlargement on the pipe string successively toward the respective seal elements, fluid pressure signal-transmitting means operable by said sensing means, fluid pressure op erated means actuatable in response to said signals from said transmitting means to successively move said valve means to said first and second positions, whereby to successively equalize the pressure across each seal element as it is approached by said enlargement while simultaneously directing well pressure to the other seal element to actuate the latter to seal off the annular space between the pipe string and the housing.

9. Automatic blow-out preventor means for use when running pipe strings into and out of a well under pressure, comprising, a tubular housing mountable on a wellhead fitting and through which a pipe string is passed, spaced apart upper and lower fluid pressure-operated seal elements mounted in the housing for radial movement into and out of engagement about the pipe string to seal 01f the annular space between the pipe string and the housing, conduit means providing fluid pressure communication to said seal elements, multi-port valve means in said conduit means movable between positions for selectively directing pressure fluid to one or the other of said seal elements, an enlargement-sensing means mounted in the housing at a point adjacent each of the respective seal elements including fluid pressure signal-transmitting means operable to provide signals indicating the approach of an enlargement on the pipe string successively toward the respective seal elements, said signals being operable to move said valve means to positions to direct operating pressure fluid successively to each of said seal elements, whereby to successively equalize the pressure across each seal element as it is approached by said enlargement while simultaneously directing fluid pressure to the other seal element to actuate the latter to seal off the annular space between the pipe string and the housing.

References Cited by the Examiner UNITED STATES PATENTS Rasmussen et al 16685 King et al 25 l1 Rasmussen 166-85 X Abercrombie 251-1 Boynton 16686X 10 CHARLES E. OCONNELL, Primary Examiner.

Claims (1)

1. AUTOMATIC BLOW-OUT PREVENTOR MEANS FOR USE WHEN RUNNING PIPE STRINGS INTO AND OUT OF A WELL UNDER PRESSURE, COMPRISING A TUBULAR HOUSING MOUNTABLE ON A WALL HEAD FITTING AND THROUGH WHICH A PIPE STRING IS PASSED, SPACED APART UPPER AND LOWER CONTRACTIBLE AND EXPANDIBLE SEAL ELEMENTS MOUNTED IN THE HOUSING ACTUATABLE TO SEAL OFF THE ANNULAR SPACE BETWEEN THE HOUSING AND THE PIPE STRING, AN ENLARGEMENT-SENSING MEANS MOUNTED IN THE HOUSING ADJACENT EACH OF THE RESPECTIVE SEAL ELEMENTS INCLUDING FLUID PRESSURE SIGNAL-TRANSMITTING MEANS OPERABLE TO PROVIDE SIGNALS INDICATING THE APPROACH OF AN ENLARGEMENT ON THE PIPE STRING SUCCESSIVELY TOWARD THE RESPECTIVE SEAL ELEMENTS, FLUID PRESSURE-OPERATED MEANS OPERABLY CONNECTED TO SAID SIGNAL-TRANSMITTINMG MEANS ACTUATABLE IN RESPONSE TO SAID SIGNALS AND ARRANGED TO SUCCESSIVELY ACTUATED SAID SEAL ELEMENTS IN INVERSE ORDER WITH RESPECT TO THE DIRECTION OF MOVEMENT OF SAID ENLARGEMENT, WHEREBY TO AUTOMATICALLY CONTRACT EACH SEAL ELEMENT AS IT IS APPROACHED BY SAID ENLARGEMENT.

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