US2841171A - Apparatus for automatically filling well bore conduit strings - Google Patents

Description

J. R. BAKER ET AL APPARATUS FOR AUTOMATICALLY FILLING WELL July 1, 1958 INVENTORS.

BAKER JOHN E Muse,

Aziorneys BORE CONDUIT STRINGS Filed April 27, 1953 United States Patent APPARATUS FOR AUTOMATICALLY FILLING WELL BORE CONDUIT STRINGS John R. Baker, Pasadena, and John F. Muse, Montebello, Califl, assignors to Baker Oil Tools, Inc., Los Angeles, Calif., a corporation of California Application April 27, 1953, Serial No. 351,394

Claims. (Cl. 137493) The present invention relates to subsurface well apparatus, and more particularly to apparatus for controlling the flow of fluids in conduit strings positioned in well bores.

Conduit strings, such as a string of drill pipe, may have a back pressure float valve incorporated in them for the purpose of preventing upward flow of fluid therein. In the case of a string of drill pipe, the valve enables the pipe to be floated in the well, and it also prevents blowouts through the drill pipe in the event the well starts to flow during the drilling operation.

Since the back pressure valve prevents drilling mud, or correspondingfluid, in the well bore from flowing into the pipe, it has heretofore been necessary to fill the pipe from the top of the hole, which is a time consuming operation.

It is, accordingly, an object of the present invention to provide an apparatus to be incorporated in a conduit string positionable in a well bore and including an upwardly closing back pressure valve, in which the conduit string automatically fills with the well bore fluid as it is being lowered therewithin.

Another object of the invention is to provide an apparatus of the character indicated, in which the fluid in the well bore is prevented from rising above a predetermined level in the conduit string, which level is lower than the hydrostatic head of fluid in the well bore externally of the conduit string.

A further object of the invention is to provide an apparatus-to be incorporated in a conduit string and which embodies a back pressure valve, wherein the conduit string is allowed to substantiallyfill with the well bore fluid while being lowered therein, the back pressure valve being allowed to open fully when fluid is pumped down the conduit string, so as not to retard or restrict its flow in that direction.

Yet another object of the invention is to provide a drill pipe float valve apparatus that enables the drill pipe to fill automatically with the well bore fluid while being lowered in the well bore, but which restricts the upward flow offluid through the drill pipe in the event of a blowout occurring in the well bore.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a 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 describedin detail, for the purpose of illustrating the general principles 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.

Referring to the drawings:

Figure 1 is a longitudinal section through one form of apparatus positioned in a conduit string, such as a string of drill pipe, with the valve mechanism in closed position;

Fig. 2 is a view similarto Fig. 1, with the valve mech- 2,841,171 iatented July I, 1958 ice anism in open position, to allow upward flow of the well bore fluid in the drill pipe;

Fig. 3 is a cross-section taken along the line 3-3 on Fig. 1;

Fig. 4 is a cross-section taken along the line 4-4 on Fig. 1.

The apparatus is disclosed in the drawings and will be described specifically as it applies to a string of drill pipe used to rotate a drilling bit secured to its lower portion. It is to be understood, however, that the invention is applicable to other conduit strings as well, such as a string of well casing, tubing, liner, and the like.

In its general aspects, the invention contemplates a valve apparatus to be incorporated in a string of drill pipe, primarily for the purpose of preventing upward-flow of fluid in the latter. However, the apparatus embodies an automatic filling feature which enables the fluid to fill the drill pipe to a limited extent while the drill pipe is being lowered in the well bore. Despite the relatively retarded or restricted upward flow of fluid in the drill pipe, when fluid is pumped downwardly in the drill pipe the valve opens to its fullest extent, allowing downward pumping of fluid to occur in a substantially unrestricted or unretarded manner.

The valve apparatus is located at a suitable point along the length of the drill pipe or other conduit string. As shown in the drawings, it is disposed in a counterbore or enlarged diameter portion 10 of a drill collar 11, which is ordinarily positioned at the lower portion of a string of drill pipe, this drill collar having a lower threaded box 12 threadedly secured to a pin 13 at the upper end of an adjacent drill pipe or drill collar section 14, or to the upper pin end of a drill bit. The upper end of the counterbore 10 in the drill collar is delineated by-a transverse shoulder 15, and the lower end of the counterbore is determined by the upper end 16 of the pin 13.

The body 17 of the valve device is mounted in the counterbore 10, this body consisting of an upper section 18 threaded into a lower section 19. The upper sec tion 18 is imperforate, being provided with peripheral grooves 20 adapted to receive seal rings 21, 22 engaging the cylindrical wall 23 of the counterbore. The seal rings 21, 22 may be of any suitable type. As shown in the drawings, they are in the nature of opposed cup-shaped packings, the base portions of which are received within the grooves 2t), the packings having-lip portions 24 extending toward each other and engaging the wall 23 of the counterbore 10 in leakproof relation. Because of the opposed relationship of the packings' 21, 22, they preclude leakage of fluid in both longitudinal directions between the upper section 18 of the body and the wall 23 of the counterbore it The lower section 19 of the body depends from the upper section 18, being generally skeletonized'in form. It includes a lower, circumferentially continuous portion 25 adapted to rest upon the upper end 16'of the box or pin 13,.and is provided with a pair of diametrically opposed, longitudinally extending ribs 26extending upwardly' therefrom. These ribs 26 merge'into an upper circumferentially continuous portion 27 which is internally threaded to receive a companion external thread on the upper body member 18. Between the longitudinally extending ribs 26, and arcuately displaced with respect thereto, the lower section has another pair of longitudinally extending ribs 28, 29 depending from the upper circumferentially continuous portion 27. These latter ribs 28, 29, however, only extend part way down toward the lower circumferentially continuous portion 25 of the lower section 19.

On one of the relatively short longitudinal ribs or=bars 29 a flapper valve member 30 is pivotally secured. This rib 29 is provided with a depending lug or ear 31 carrying a transversely extending fulcrum or pivot pin 32 on which are mounted the bifurcated ears or portions 33 of the flapper valve head member 30, the flapper valve head member being capable of extending laterally across the apparatus toward the other opposed short rib 28. This flapper valve member has a stop arm or finger 34 at its free end adapted to engage the lower end 35 of the rib 28, and thereby limit upward movement of the valve head 30. When the arm 34 engages such lower end of the rib 28, the valve head 30 is preferably disposed in a position substantially normal to the axis of the apparatus (Fig. 1). As disclosed, the central portion of the valve head is frusto-conical in shape, converging in an upward direction and providing a tapered surface 36 adapted to be engaged by a slidable valve member 37, capable of moving longitudinally of the body for the purpose of allowing the drill pipe to fill automatically with the well bore fluid, as the drill pipe is lowered within the well bore.

The valve member 37 is slidable along the ribs 28, 29 of the lower body section 19 and also along a depending skirt 38 of the upper body section 18, which is spaced inwardly from the lower body section to provide an annular space or chamber 39 in which the sleeve valve member 37 is slidable.

The sleeve valve member 37 may be considered as constituting a seat against which the flapper valve head member 30 is engageable, for the purpose of closing the valve device against upward flow of fluid. However, the seat 37 may shift upwardly out of engagement from the valve member 30, to permit some passage of fluid around the flapper valve member under the conditions described below. The sleeve valve member 37 is generally cylindrical in form, its inner walls 40 being slidable along the lower portion of the body skirt 38, leakage between the wall and this skirt being prevented by a suitable side seal, which may be in the form of a rubber or rubber-like O ring 41 disposed in a peripheral groove 42 in the lower portion of the skirt 38 and slidably engaging the inner cylindrical wall 40 of the sleeve valve. The outer cylindrical wall 43 of the sleeve valve is slidable along the inner surfaces 44 of the inwardly projecting flanges 45 provided at the lower portions of the short longitudinally extending ribs 28, 29. These inwardly projecting portions provide upwardly facing stop shoulders 46 adapted to be engaged by a lower shoulder 47 provided by the lower end of an outwardly directed flange 48 at the upper end of the sleeve valve 37. The lower portion of the sleeve valve is provided with an inwardly directed flange 49 whose lower, inner edge 50 actually constitutes the seat engageable by the tapered surface 36 of the valve head member 30. The upper end or shoulder 51 of this inwardly directed flange 49 constitutes a stop engageable with the lower end of the body skirt 38, to limit upward movement of the sleeve valve 37 within the body 17.

The sleeve valve 37 is urged in a downward direction, to place its lower seat 50 in a position to be engaged by the flapper valve 30, by a helical compression spring 52 disposed in the chamber 39, the upper end of this spring engaging a transverse shoulder or spring seat 53 on the upper body section 18 adjacent its external thread, the lower end of the spring engaging the upper end of the sleeve valve member 37. When the valve head 30 is in'its upper position, with the stop arm 34 engaging the lower end 35 of the longitudinal rib 28, then the spring 52 can shift the sleeve valve member 37 downwardly to place its seat 50 in engagement with the head member 30. When in this position, the upper external flange 48 of the sleeve valve member is spaced slightly above the shoulders 46 provided by the inwardly directed portions 45 of the shortened ribs 28, 29. In the event the flapper valve head member 30 is swung downwardly about its pivot 32 out of engagement from its seat 50, then the sleeve valve member 37 is shifted downwardly a slight distance by the spring 52 until its flange 48 engages the rib shoulders 46.

The sleeve valve 37 can shift upwardly against the force of the helical spring 52 as the string of drill pipe is being lowered in the well bore. The hydrostatic head of fluid externally of the string of drill pipe is availed of to shift the sleeve valve upwardly away from the head member 30, to allow fluid to flow upwardly around the latter and into the drill pipe. However, when the hydrostatic head of fluid within the drill pipe reaches a certain predetermined value, the spring 52 will shift the sleeve valve 37 back downwardly into engagement with the valve head 30, or to closed position. This predetermined fluid level within the drill pipe string will always be lower than the fluid level externally of the drill pipe string, because of a certain relationship that will now be described.

It is to be noted that the external cylindrical surface 43 of the sleeve valve 37 is only engaged by the inwardly projecting portions 45 of the short longitudinal ribs 28, 29, because of the skeletonized construction of the lower body section 19. The fluid under pressure in the drill pipe below the sleeve valve 37 is thus capable of passing into the chamber 39, acting not only upon the lower surface 60 of the sleeve valve, but also upon its upper surface 61, as well as the lower shoulder 47 provided by the external sleeve flange. This is to say, the fluid below the sleeve valve 37 is capable of acting in an upward direction over the combined areas of the lowermost end 60 of the sleeve valve 37 and of the lower shoulder 47, which may be designated as the annular area R. It is capable of acting in a downward direction over the area S of the upper end 61 of the sleeve valve. The difference or resultant between these areas is actually the area A of the inwardly projecting lower flange portion 49 of the sleeve, which is the area between the inner surface 65 of the lower flange and the inner cylindrical wall 40 of the sleeve valve member 37. This area may be made relatively small if desired, depending upon the design of the apparatus.

The spring 52 is exerting a downward force, tending to hold the sleeve valve 37 in its downward position in engagement with the valve head 30, which precludes upward flow of fluid around the valve head 30 and into the drill pipe 11 thereabove. While the sleeve valve 37 is engaging the head, the fluid externally of the drill pipe, which passes into the lower pipe section 14, is acting in an upward direction over the effective or resultant area A of the sleeve valve, which is the area of the resultant surface or shoulder 51 of the flange 49, tending to shift the sleeve valve in an upward direction away from the valve head 30 and against the force exerted by the helical spring 52. As the drill pipe is being lowered through the fluid in the well bore, the hydrostatic head or pressure of the external fluid acting over the resultant area A of the sleeve valve is increasing and eventually will be sufiicient to shift the sleeve valve in an upward direction against the force of the spring 52 and of whatever fluid might be contained within the drill pipe string 11 thereabove. The sleeve valve member 37 is thereby moved upwardly to open position out of contact from the valve head 30, the fluid then flowing upwardly around the latter and through the central passage 66 through the upper body section 18, and on into the sections of drill pipe 11 thereabove. The fluid level in the drill pipe above the sleeve valve 37 increases, the hydrostatic head of such fluid acting in a downward direction over the upper shoulder surface 51 having the area A. This downward force is supplementing the force of the spring 52, tending to shift the sleeve 37 back down to its closed position with its seat 50 engaging the tapered surface 36 of the valve head 30.' Eventually, the fluid level in the drill pipe 11 will rise to the point where the force attributable to it and acting downwardly on the sleeve valve 37, coupled with the force of the spring 52, is sufficient to offset the external hydrostatic head acting in an upward direction on the sleeve valve over the sleeve valve area be represented by the product P A. The force of the hydrostatic head of fluid internally of the drill pipe may be designed by the product P A; wherein P =the unit pressure attributable to the internal hydrostatic head;

P =the unit pressure attributable to the external hydrostatic head;

A=the area over which each hydrostatic head is acting;

F=force exerted by the spring.

The equilibrium condition exists when From the foregoing formula, it is quite evident that an equilibrium condition will exist, in which the sleeve valve member is on the point of being opened or closed, when the hydrostatic head of fluid P internally of the drill pipe is less than the hydrostatic head of fluid P externally of the drill pipe by a value corresponding to the force F of the spring divided by the area A. Assuming, by way of example, that the spring 52 exerts a force when the sleeve valve member 37 is closed against the valve head 30 of 100 lbs. and the area A is one-half square inch, then the hydrostatic head of fluid internally of the drill pipe will be less than the hydrostatic head of fluid externally of the drill pipe by 200 p. s. i. Assuming that the fluid, which is usually drilling mud, has a specific gravity somewhat greater than that of water, this pressure difference is equal to approximately 400 feet of fluid head.

In other words, from the above specific example, the valve 37 will be at the point of opening whenever the external hydrostatic head of fluid exceeds 400 feet over the fluid head internally of the drill pipe. The sleeve valve 37 will be shifted by the spring 52 back to its closed position whenever the fluid level inside of the drill pipe rises to 400 feet below the external fluid level.

Accordingly, as the drill pipe is lowered through the fluid in the well bore, the sleeve valve 37 will shift upwardly against the force of the spring 52, to allow the drill pipe to fill with fluid, but only up to a predetermined lower level than the external height of the fluid around the drill pipe. Of course, if the drill pipe were to be filled completely with fluid, as from the top thereof, then the sleeve valve 37 would be held in its downward position.

Despite the fact that the drill pipe float valve apparatus enables the drill pipe to fill with the fluid, whenever downward pumping of fluid in the drill pipe occurs, the flapper valve member 30 is shifted downwardly to its fully open position away from its companion seat 50, as indicated in broken lines in Fig. 1, allowing full and free flow of fluid down through the valve apparatus and through the drill pipe itself. Any tendency for fluid to flow in a reverse direction will carry the valve head 30 back to its closed position, with its stop arm 34 in engagement with the lower end 35 of the longitudinal rib 28. If desired, a'relatively light coil spring 70 may be mounted about the pivot pin 32, one arm 71 engaging the valve head member 30 and its other arm 72 engaging the lower portion of the longitudinal rib 29, so as to tend to lightly hold the valve head member 30 in its upward position, shown in full lines in Figs. 1 and 2.

In the event the drill pipe is full of fluid and the well tends to blow in through the drill pipe during the drilling operation, the pressure'below the sleeve valve 37 would have to increase sufficiently to overcome the force of the spring 52; The full pressure would be prevented from being imposed in the drill pipe above the valve apparatus, since the sleeve valve 37 would only be shifted upwardly when the equilibrium condition set forth in the above equation is satisfied. Since the fluid in the drill pipe will then be extending to the top of the hole, it will take a substantially greater pressure over and beyond the hydrostatic head of fluid internally of the drill pipe to shift the sleeve valve member to open position. The amount of extra pressure required can be made quite extensive either by providing a spring 52 having a great force, or merely by reducing the value of the area A. From the above equation, it is evident that if the value of the area A is made quite small, then the pressure F for shifting the sleeve valve upwardly to open position must be made much greater than the value of the pressure P internally of the drill pipe string. Accordingly, the apparatus can readily be designed to minimize, if not completely eliminate, the tendency of a blowout occuring upwardly through the drill pipe.

The inventors claim:

1. In apparatus for controlling the flow of fluid in a conduit string positionable in a well bore: a valve body adapted to be disposed in a generally vertical position in the conduit string; a first valve member in said body; a second valve member in said body movable upwardly with respect to said body into engagement with said first valve member to restrict upward flow of fluid between said members and movable downwardly out of engage ment from said first member to allow flow of fluid therebetween; spring means engaging said first valve member for urging said first valve member downwardly toward engagement with said second valve member; said first valve member having a downwardly directed surface of a total area acted on byfluid under pressure therebelow, when said valve members are in engagement with each other, which tends to shift said first valve member in an upward direction out of engagement from said second valve member; said first valve member having an upwardly directed surface of a total area acted on by fluid under pressure therebelow, when said valve members are in engagement with each other, which tends to shift said valve member in a downward direction into engagement with said second valve member; the total area of said downwardly directed surface being greater than the total area of said upwardly directed surface.

2. In apparatus for controlling the flow of fluid in a conduit string positionable in a well bore: a valve body adapted to be disposed in a generally vertical position in the conduit string; a first valve member in said body; a second valve member in said body movable upwardly with respect to said body into engagement with said first valve member to restrict upward flow of fluid between said .members and movable downwardly out of engagement from said first member to allow flow of fluid therebetween; spring means engaging said first valve member for urging said first valve member downwardly toward engagement with said second valve member; said first valve member having a downwardly directed surface of a total area acted on by fluid under pressure therebelow, when said valve members are in engagement with each other, which tends to shift said first valve member in an upward direction out of engagement from said second valve member; said first valve member having an upwardly directed surface of a total area acted on by fluid under pressure therebelow, when said valve members are in engagement with each other, which tends to shift said valve member in a downward direction into engagement with said second valve member; the total area of said downwardly directed surface being greater than the total area of said upwardly directed surface; said first valve member having a resultant upwardly directed surface acted on by fluid. under pressure thereabove and tending 7, to shift said first valve member in a downward direction toward engagement with said second valve member.

3. In apparatus for controlling the flow of fluid in a conduit string positionable in a well bore: a valve body; a first valve member in said body; a second valve mem her in said body movable in one direction with respect to said body into engagement with said first valve member to restrict flow of fluid between said members in such one direction and movable in the opposite direction out of engagement from said first member to allow flow of fluid therebetween; spring means engaging said first valve member for urging said first valve member in said opposite direction toward engagement with said second valve member; said first valve member having a surface facing in said opposite direction of a total area acted on by fluid under pressure upstream of said first valve member, when said valve members are in engagement with each other, which tends to shift said first valve member in said one direction out of engagement from said second valve member; said first valve member having a surface-facing in said one direction of a total area acted on by fluid under pressure upstream of said first valve member, whensaid valve members are in engagement with each other, which tends to shift said first valve member in said opposite direction into engagement with said second valve member; the total area of said surface facing in said opposite direction being greater than the total area of said surface facing in said one direction.

4. In apparatus for controlling the flow of fluid in a conduit string positionable in a well bore: a valve body; a first valve member in said body; a second valve member in said body movable in one direction with respect to said body into engagement with said first valve member to restrict flow of fluid between said members in such one direction and movable in the opposite direction out of engagement from said first member to allow flow of fluid therebetween; spring means engaging said first valve member for urging said first valve member in said opposite direction toward engagement with said second valve member; said first valve member having a surface facing in said opposite direction of a total area acted on by fluid under pressure upstream of said first valve member, when said valve members are in engagement with each other, which tends to shift said first valve member in said one direction out of engagement from said second valve member; said first valve member having a surface facing in said one direction of a total area acted on by fluid under pressure upstream of said first valve member, when said valve members are in engagement with each other, which tends to shift said first valve member in said opposite direction into engagement with said second valve member; the total area of said surface facing in said opposite direction being greater than the total area of said surface facing in said one direction; said first valve member having a resultant surface facing in said one direction and acted on by fluid under pressure downstream of said first valve member which tends to shift said first valve member in said opposite direction toward engagement with said second valve member.

5. In apparatus for controlling the flow of fluid in a conduit string positionable in a well bore: a valve body adapted to be disposed in a generally vertical position in the conduit string; a first valve member in said body; a second valve member in said body movable upwardly with respect to said body into engagement with said first valve member to restrict upward flow of fluid between said members and movable downwardly out of engagement from said first member to allow flow of fluid therebetween; spring means engaging said first valve member for urging said first valve member downwardly toward engagement with said second valve member; said first valve member having a downwardly directed surface of a total area acted on by fluid under pressure therebelow, when said valve members are in engagement with each other, which tends to shift said first valve member in an upward direction out of engagement from said second valve member; said first valve member having an upwardly directed surface of a total area acted on by fluid under pressure therebelow, when said valve members are in engagement with each other, which tends to shift said valve member in a downward direction into engagement with said second valve member; the total area of said downwardly directed surface being greater than the total area of said upwardly directed surface; and means in said body engaging said second valve member to limit its upward movement with respect to said body.

6. In apparatus for controlling the flow of fluid in a conduit string positionable in a well bore: a valve body adapted to be disposed in a generally vertical position in the conduit string; a valve seat slidable longitudinally in said body; a valve member in said body movable upwardly into engagement with said seat and downwardly out of engagement from said seat; spring means engaging said seat to urge it downwardly toward engagement with said member; said seat having resultant upwardly and downwardly facing surfaces all subject to the pressure of fluid below said seat when said seat engages said valve member; the resultant of said surfaces facing downwardly.

7. In apparatus for controlling the flow of fluid in a conduit string positionable in a well bore: a valve body; a valve seat slidable longitudinally in said body; a valve member in said body movable in one direction into engagement with said seat and in the opposite direction out of engagement from said seat; spring means engaging said seat to urge it in said opposite direction toward engagement with said member; said seat having oppositely facing surfaces all subject to the pressure of fluid at the side of said seat at which said valve member is located when said valve seat engages said valve member; the resultant of said surfaces facing in said opposite direction.

8. In apparatus for controlling the flow of fluid in a conduit string positionable in a well bore: a valve body adapted to be disposed in a generally vertical position in the conduit string; a valve seat slidable longitudinally in said body; a valve member in said body movable upwardly into engagement with said seat and downwardly out of engagement from said seat; spring means engaging said seat to urge it downwardly toward engagement with said member; said seat having a downwardly facing surface of a total area subject to the pressure of fluid below said seat, when said seat is in engagement with said valve member, which tends to elevate said seat from said valve member against the force exerted by said spring means; said seat having an upwardly facing surface of a total area subject to the pressure of fluid below said seat, when said seat is in engagement with said valve member, which tends to lower said seat into engagement with said valve member; the total area of said downwardly facing surface being greater than the total area of said upwardly facing surface; said seat having a resultant upwardly facing surface subject to the pressure of fluid with in said body and above said seat tending to shift said seat downwardly toward engagement with said valve member.

9. In apparatus for controlling the flow of fluid in a conduit string positionable in a well bore: a valve body having an imperforate inner wall and adapted to be disposed in a generally vertical position in the conduit string; a sleeve valve seat slidable along the exterior of said wall in leakproof relation with respect thereto; a valve member in said body movable upwardly into engagement with said seat and downwardly out of engagement from said seat; spring means engaging said seat to urge said seat downwardly toward engagement with said valve member; said seat having external upwardly and downwardly facing surfaces all subject to the pressure of fluid below said seat when said seat engages said valve member, the area of such downwardly facing surface being greater than the area of such upwardly facing surface; said seat having a resultant upwardly facing surface subject to the pressure of fluid within said wall and tending to shift said seat downwardly toward engagement with said valve member.

10. In apparatus for controlling the flow of fluid in a conduit string positionable in a well bore: a valve body having an imperforate wall and adapted to be disposed in a generally vertical position in the conduit string; a sleeve valve seat slidable along said wall in leakproof relation with respect thereto; a valve member in said body movable upwardly into engagement with said seat and downwardly out of engagement from said seat; spring means engaging said seat to urge said seat downwardly toward engagement with said valve member; said seat having external upwardly and downwardly facing sur- 5 2,472,049

faces all subject to the pressure of fluid below said seat, when said seat engages said valve member, the area of such downwardly facing surface being greater than the area of such upwardly facing surface, whereby said pressure of fluid below said seat tends to elevate said seat from said valve member; said seat having a resultant upwardly facing surface subject to the pressure of fluid within said wall and tending to shift said seat downwardly toward engagement with said valve member.

References Cited in the file of this patent UNITED STATES PATENTS Anderson Aug. 13, 1929 Strid Oct. 19, 1948 Schneck May 31, 1949

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