Mud Saver Valve

Abstract

A mud saver valve adapted to be disposed below a kelly for controlling the discharge of mud through the kelly into the drill string and for preventing loss of mud at the derrick floor from the kelly when it is disconnected with the mud saver valve from the drill string, wherein means are provided for preventing a closure of the mud saver valve, even though the mud supply pressure to the kelly is cut off, if there is well pressure in the drill string which might blow out upon a disconnection of the kelly, whereby the danger of having a well blowout upon a disconnection of the kelly may be avoided.

Description

BACKGROUND OF THE INVENTION

The field of this invention is mud saver valves for connection between a kelly and a drill string.

Mud saver valves of different types are well known, but so far as is known, such valves have heretofore been constructed so that they closed when the mud supply pressure to the kelly was cut off. As a result, the operator could not tell what the well pressure was after the mud saver valve was closed, so that the operator did not know if the well pressure was high enough to cause a well blowout when the valve and kelly were disconnected from the drill string. Such prior constructions thus created a serious danger in instances where the well pressure was high enough to cause a well blowout, because until the kelly and mud saver valve were disconnected from the drilling string, the operator did not know whether a blowout would occur, and then it was already too late to bring the well under control.

SUMMARY OF THE INVENTION

The present invention relates to a new and improved mud saver valve adapted to be connected below a kelly for controlling the flow of mud through the kelly into a drill string, wherein means are provided for preventing a closure of the mud saver valve after the mud supply pressure to the kelly is cut off if there is well pressure in the drill string which would cause a blowout upon a disconnection of the kelly and mud saver valve from the drill string. Means are also provided for indicating to the operator that such well condition exists so that such disconnection may be avoided until the well is brought under control. The mud saver may be selectively locked open to bleed off well pressure or perform other operations with the kelly connected to the drill string.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view, partly in elevation, illustrating the mud saver valve of this invention connected between a kelly at its upper end and a drill string at its lower end, and with the valve in the closed position;

FIG. 2 is a view similar to FIG. 1, but illustrating the valve in the open position;

FIG. 3 is a sectional view taken on line 3--3 of FIG. 2;

FIG. 4 is a sectional view taken on line 4--4 of FIG. 2; and

FIG. 5 is a view showing a portion of the mud saver valve of FIG. 1 and 2, the view being taken on line 5--5 of FIG. 2 and illustrating in particular the lock means with the valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the drawings, the letter V indicates generally the mud saver valve of this invention which is connected below a kelly K during normal operations. The lower end of the valve V is periodically connected and disconnected from a string of drill pipe P, a portion of which is shown in FIGS. 1 and 2.

The mud saver valve V includes a body 10 which is generally cylindrical in shape and which has upper internal threads 10a and lower external threads 10b. The upper internal threads 10a are adapted to receive corresponding threads 11 on the lower end of a conventional kelly K, a portion of which is shown in FIGS. 1 and 2. The kelly K is connected in the conventional manner in an oil well derrick, through a conventional swivel (not shown) to a source of drilling mud or fluid under pressure, which is supplied through the bore 12 of the kelly 11 to the valve V as will be more fully explained.

The valve V has a closure element 15 which is essentially a ball valve having a bore 15a therethrough in one direction so that by turning the ball or closure element 15 ninety degrees, the element 15 may be moved from the closed position (FIG. 1) to the open position. The closure element 15 preferably has substantially flat parallel sides 15b (FIGS. 1 and 3), with pivot slots 15c formed therein, in the well known manner for receiving pivot pins 16 therein, whereby the ball valve or closure element 15 is caused to rotate to and from the closed and open positions when pressure is exerted thereon, as will be well understood.

The pivot pins 16 are preferably threaded or are otherwise engaged in suitable openings 10c (FIG. 3) of the body 10, and each of the pins 16 also extends through an opening 18a in the two side plates 18 disposed on each side of the closure element 15. Such plates 18 have internal flat surfaces 18b which are in sliding engagement with the flat surfaces 15b to prevent the turning of the valve element 15 about its vertical axis as it is being turned to and from the closed and open positions. The opening 18a in each of the guide plates 18 is actually a slot for receiving the pin 16 as can be seen by comparison of FIGS. 1 and 2. Thus, such slots 18a permit the guide plates 18 to move longitudinally or vertically relative to the pins 16, as will be more evident hereinafter.

The upper ends of the guide plates 18 are preferably joined together by a circular portion 18d having internal threads 18e (FIGS. 1 and 2), which threads 18e are in threaded engagement with corresponding threads on a tubular valve operator 20 having a piston 21 at its upper end.

The lower end of the valve operator 20 engages an upper wear ring 22 which is seated in coacting engagement with the upper portion of the closure element 15 as seen in FIG. 1 and 2. A similar wear ring 23 is disposed below the closure element 15 and in engagement therewith, and it is engaged by a force transmitting ring 25. The ring 25 preferably has an extension 25a which extends into a recess 18e of the lower end of the plates 18 so that the ring 25 travels with the plates 18, as will be more evident hereinafter.

Preferably, a control bolt 28 is threaded or is otherwise connected to the lower end of the annular ring 25, at two or more points to provide for guiding a coil spring 29 therewith. There may be more than one such coil spring, but only one is illustrated in the drawings. Normally, there are at least two of such coil springs and they function in the same manner as hereinafter described in connection with the spring 29 which is illustrated in FIGS. 1 and 2.

The coil spring 29 as illustrated in FIG. 1 and 2 is disposed above a retaining collar 30 having an opening 30a therethrough, through which the bolt 28 extends. The collar 30 has a hollow bore 30b so that the head 28a of the bolt 28 may move freely therein. When the spring or springs 29 are in the compressed condition as illustrated in FIG. 2, they are exerting a predetermined upward force tending to rotate the ball element 15 from the open position of FIG. 2 to the closed position of FIG. 1.

Such resilient spring pressure acting on the closure element 15 is overcome by fluid pressure in the bore of the valve V acting on the piston 21. As best seen in FIGS. 1 and 2, the piston 21 is annular and is enlarged in its external diameter as compared to the lower portion of the annular actuating member 20 therewith, so as to provide an inclined annular surface 21a below the piston 21, for a purpose to be hereinafter described. An annular seal 21b of rubber or other suitable resilient material is provided on the external surface of the piston 21 for engagement with a retainer sleeve 35 which is threaded or is otherwise mounted in the bore of the body 10 as shown in FIGS. 1 and 2. The lower end of the retainer sleeve 35 has a seal 35a which is annular and which is preferably formed of rubber or other resilient material which engages the external surface of the annular valve actuator 20 for sealing therewith. The upper portion of the liner 35 preferably has spanner openings 35b for receiving a spanner wrench to facilitate the threading of the sleeve 35 into the position shown in FIGS. 1 and 2, and the upper portion of such sleeve 35 is then engaged by the lower end of the kelly K to secure the sleeve 35 in the body 10. The piston 21 may also have a stop section 21c at its upper end with suitable spanner wrench openings 21d so that such piston 21 and the valve actuator 20 may be threaded into the threads 18e, as previously noted. Also, the stop section 21c serves to contact the lower end of the kelly K to limit the upward travel of the actuator 20 so as to stop the rotation of the closure element 15 when it reaches the closed position shown in FIG. 1.

The area externally of the piston 21 in the body 10 is exposed to the atmosphere and thus to a second or atmospheric pressure through one or more lateral openings 40 formed in the wall of the body 10 (FIGS. 1, 2 and 4). As illustrated in the drawings, there are three of such openings 40 and they all communicate with the area below the piston 21 and above the seal 35a. An opening 35c is provided through the liner 35 in direct alignment with each of the openings 40 in the body 10 so that the lower portion of the piston 21 is exposed to atmospheric pressure while the upper portion of the piston 21 is exposed to whatever fluid pressure exists within the bore of the valve actuating member 20, as will be more fully explained. The differential in pressure thus acts across the piston 21, causing a downward force to urge the piston 21, its annular portion 20 therebelow and the guide plates 18 downwardly. The ring 25 is also urged downwardly from the position of FIG. 1 to compress the spring 29 as the element 15 is moved from the closed position of FIG. 1 to the open position of FIG. 2.

The ports or openings 40 also serve an additional purpose in that each has an indicator button or elongated element 43 slidably mounted therein and urged inwardly by a coil spring 44 which engages an annular flange 43a. When the piston 21 is in the raised position, so that the element 15 is in the closed position (FIG. 1) the spring 44 with each indicator button 43 acts to urge the indicator button 43 inwardly into contact with the external surface 20a of the annular sleeve portion 20 of the valve actuator. In this position, the outermost end of each of the indicator buttons 43 is retracted so that it is not readily seen by an operator. However, when the piston 21 moves downwardly to the open position, the inclined or tapered actuating surface 21a on the lower part of the piston 21 forces each of the indicator buttons 43 outwardly so that the outer end of each of such buttons 43 is then substantially flush with the external surface of the body 10 (FIGS. 2 and 4) at which time such indicator buttons are readily visible to an operator so that he knows that the closure element 15 is in the open position.

In some instances, it is desirable to lock the valve V in the open position illustrated in FIG. 2, wherein fluid may flow through the valve element 15. For this purpose, a lock means L is provided in the body 10. The lock means L is mounted in an opening 10d of the body 10, which preferably has threads for receiving an annular bushing 50 in threaded engagement therewith. A rotatable locking member 51 having a recess 51a with wrench flats therein for rotation therein by a wrench, is rotatably mounted in the bushing 50. The inner end 51a of the member 51 is enlarged to prevent the member 51 from moving radially outwardly from the bushing 50 when it is rotated. A guide pin 52 is formed integrally with or is connected with the member 51 and it extends into a longitudinal slot 20b formed in the valve actuator member 20. The locking member 51 has a moon shaped locking segment 51b formed on the inner portion thereof (FIGS. 1, 2 and 5) which is disposed so that when it is in its lowermost position (FIGS. 2 and 5) it fits within a curved recess 20c of the annular portion 20 (FIG. 5). Thus, when the locking member 51 is in the locking position shown in FIGS. 2 and 4, the locking segment 51b is disposed in the recess 20c so as to prevent upward movement of the guide plate 18 therebelow and the annular portion 20 and the piston 21 thereabove. Since the valve actuator is thus prevented from moving longitudinally relative to the body 10, the valve element 15 is prevented from moving from the open position and is therefore locked in the open position.

The locking member 51 may be rotated from the position shown in FIG. 2 to the position shown in FIG. 1 by the use of a wrench in the wrench opening 51a, or by any other suitable means. When the locking member 51 is in the position shown in FIG. 1, which is indicated by the dotted lines 51b in FIG. 5, the annular portion may then move upwardly until the recess 20c is at the uppermost position with the surface 20d then in contact with the lower annular edge 35d of the liner 35. So long as the locking member 51 is in the upper or inactive position shown in FIG. 1, it does not have any effect upon the operation of the valve actuator 20 and thus on the opening and closing of the closure element 15.

In the operation or use of the mud saver valve V of this invention, it is connected below the kelly K as illustrated in FIGS. 1 and 2, with the kelly K connected below a swivel (not shown) and with the bore of the kelly and thus the bore of the mud saver valve V in communication with a source of mud under pressure. Normally, this would be a mud pump (not shown) of conventional construction. When it is desired to lower a stand of pipe into the well, the lower threads 10b on the mud saver valve V are threaded into the upper end of the stand of pipe P which is to be lowered with the rest of the drill string therebelow. Such operation is conducted in the normal manner and as soon as drilling is commenced with the drill string P in the well and a drill bit therebelow, drilling mud is circulated down through the kelly K from the source or supply of such drilling mud. The pressure of the drilling mud acts to urge the piston 21 downwardly by creating a differential pressure across the piston 21 since the lower part is exposed to the atmosphere through the opening or openings 40 as previously explained. The downward movement of the piston 21 causes it together with the parts connected therewith, including the annular portion 20 and the actuating plates 18 to rotate the valve element 15 from the closed position of FIG. 1 to the open position of FIG. 2, thereby compressing the spring or springs 29. So long as there is sufficient pressure within the bore of the valve V to overcome the spring pressure of the spring or springs 29, the closure or valve element 15 thus remains in the open position.

Also, if desired, the valve element 15 may be locked in the open position by rotating the locking member 51 from the inactive position of FIG. 1 to the locking position of FIG. 2. This occurs normally only when it is desirable to keep the valve 15 open for running tools therethrough or for bleeding pressure from the well. Normally, the locking assembly L is in the inactive position of FIG. 1.

When the supply of mud pressure is cut off at the source so that there is no longer any mud pressure supplied through the kelly K to the mud saver valve V, if there is no well pressure acting upwardly through the string of drill pipe P, the valve element 15 will be forced upwardly to the closed position by the spring or springs 29 as soon as the supply mud pressure is cut off to the kelly. However, if the pressure within the drill pipe string P is sufficiently high to overcome the spring pressure of the spring or springs 29, which would be indicative of a sufficient pressure to cause a well blowout, then the well pressure will act upon the piston 21 even after the mud pressure supply through the kelly is cut off and this will hold the valve 15 in the open position. The operator will observe that the indicator buttons 43 are substantially flush as shown in FIG. 2 after he has cut off the mud supply pressure to the kelly K and he will then know that the pressure within the mud saver valve V is caused by high pressure within the drill pipe string P which might cause a blowout if the valve V is disconnected from the drill pipe string P.

In the event the operator discovers that the well pressure in the pipe string P is thus high enough to possibly cause a blowout if the mud valve V is disconnected from the pipe string P, the usual well operations are conducted such as increasing the density of the mud to bring the well pressure in the pipe string under control. After the density of the drilling mud is increased, the supply mud pressure is again cut off and then, if the indicator buttons 43 do not come out to the flush indicator position of FIG. 2, the operator knows that the well is then under control and he can safely disconnect the threads 10b of the mud saver valve from the upper end of the pipe string P.

It will of course be understood that the mud saver valve V performs the function of preventing the loss of the drilling mud within the kelly K from dropping therefrom when the valve V is disconnected from the pipe string P since the closure element 15 confines the drilling mud thereabove.

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

Claims

I claim:

1. A mud saver valve adapted to be connected between a kelly and a drill string, comprising:

a valve body having a longitudinal bore therethrough;

a valve closure element disposed in said valve body having a valve bore opening formed therethrough for rotational movement to and from an open position in which fluid may flow therethrough and a closed position in which fluid flow through said bore is closed off to confine the drilling fluid above said valve closure element;

a valve operator means in said bore for moving said valve closure element to and from said closed position and said open position;

means acting on said valve operator means to urge said valve closure element from said open position to a closed position;

said valve operator means having piston means therewith, with one side thereof exposed to fluid pressure in said bore and the other side thereof exposed to a second fluid pressure, for moving the valve operator means to hold said valve closure element in the open position in response to fluid pressure in said bore sufficient to overcome the closing urging of said means and the second fluid pressure on said operator means; and

an opening formed in said valve body for communicating said second fluid pressure from adjacent said valve body with said piston means for providing a differential pressure urging on said piston means the same as the pressure differential between the pressure in said bore and the second pressure adjacent said valve body wherein said valve closure element is operated closed when said valve body may be safely disconnected from the drill string.

2. The structure set forth in claim 1 wherein said second fluid pressure is atmospheric pressure.

3. The structure set forth in claim 1, including:

indicator means in said valve body for indicating to an operator that said valve closure element is in the open position for thereby indicating the presence of well pressure in said bore after the fluid supply pressure to said bore is cut off.

4. The structure set forth in claim 3, wherein said indicator means includes:

an indicator element;

said valve body having an opening in its wall for slidably receiving said indicator element; and

means on said valve operator co-acting with said button for moving it to an indicator position when said closure element is in the open position.

5. The structure set forth in claim 4, including:

means for moving said indicator button to a retracted position when said closure element is in the closed position.

6. The structure set forth in claim 1, including:

lock means for locking said closure element in said open position.

7. The structure set forth in claim 6, wherein said lock means includes:

means operable from externally of said body for actuating said lock means.

8. The structure set forth in claim 6, wherein said lock means includes:

means for moving said lock means to an inactive position wherein it has no operational effect on said closure element as it is moved to and from said open and closed positions.