GB2189276A - A mud saver valve sub - Google Patents

Abstract

A kelly mud saver valve sub 10 is provided having a tubular valve body 12 with an annular seat 18 fixed in the interior of the valve body. A tubular closure member 22 is reciprocally mounted within the valve body, and is biassed with a helical spring 38 into a closing relationship with the annular seat. Unidirectional seals 40, 44 are provided around the closure member to form a chamber 34 in which the spring is retained, the unidirectional seals permitting fluid only to leave the chamber but not enter it. Spacer rings 32, 33 are provided at the downhole end of the chamber to prevent downhole pressure from being communicated past the spacer rings. The closure member in the valve accordingly opens solidly under the force of hydraulic pressure since the pressure acts against a larger area of the uphole end of the closure member than of the downhole end. <IMAGE>

Description

SPECIFICATION Improvements in or relating to a mud saver valve sub This invention relates to a mud saver valve su b, a nd more particularlyto a kelly mud saver valve sub for preventing lossofdrilling mudfrom abovethevalve when the drill string is broken below the valve.

In the drilling of oil and gas wells, a drill string is lengthened bydisconnecting the kellyfrom the drill string and inserting an additional segment of drill string between the kelly and the existing string.

When the connection between the kelly and the drill string is broken, drilling mud contained within the kelly spills out onto thejob site. Spillage ofthe drilling mud presents hazards to the safety of drilling personnel, increased expense as a result of the wasted mud, environmental pollution, and time delays occasioned by the necessity of removing workmen from the site to avoid mud spray.

To prevent spillage of the mud when the connection with the drill string is broken, mud saver valves have been developed for placement between the drill string and the kelly. These valves are designed to open when drilling mud is introduced into the drill string, but to close when the introduction of drilling mud stops. Closure ofthe valve retains mud inthekellywhentheconnection with the drill string is broken.

An example of an unsuccessful attempt two design such a valve is shown in U.S. Patent No. 4,364,407 issued to Hilliard, which shows a mud savervalve having a tubular body with an annularseat ring mounted within the body. A closure member is axially movably mounted within the body for engagement with the seat ring. The closure member includes a bore substantially coaxiallyaligned with the central opening ofthe annular seat ring, and a flange extends radially outwardly from the closure membertoslidinglyengagethe interiorofthe cylindrical body.A plug is removably mounted in the closure memberwith a shear ring, and the plug is movable between a first position in which the plug sealing engagestheshearring andasecond position that allows fluid to flow upwardly between the plug and the shear ring. The Hilliard device has, however, only a single seal around the flange that extends radially outwardly from the piston. Accordingly, the piston opens and closes in response to the flow of mud from the kelly into the drill string. Since most drilling operations use duplex ortriplex pumps, there is a variation in the flow of drilling mud, and as the flow varies the entire valve oscillates up and down thereby causing wear on the flange, the annular seat ring, and adjacent parts thereto.The proposedvalve of Hilliard also suffersfrom the drawback that the bore of the sub and the flange are exposed to the turbulent flow of abrasive drilling mud, and is accordingly worn down quickly in use.

U.S. Patent No. 4,128,108 issued to Parker, et al has the same problem as experienced by Hilliard, i.e.

there is only one seal at the top ofthe closure member so that the force of the velocity ofthe drilling mud holds the tool in its open position.

Another problem with the Parker proposal is that the seating faces ofthe closure member and annular seat are flat, which provides a leak path for mud under high pressure because flat faces do not self center.

U.S. Patent No. 3,965,980 issued to Williamson came closerto solving the problem of oscillation in the valve due to variation in flowofthe mud.

Williamson provided a piston body having unidirectional seals at its top and bottom,thereby forming an annular chamber around the piston body. The one way seals perm it fluid to leavethe annular chamber, but not enter it; the piston body then theoretically opens and closes in response to differential hydraulic force above and below the piston, thereby avoiding oscillation of the piston in responseto variations of flow from duplex ortriplex pumps. Williamson, however, did not provide any means for reducing the surface area ofthe piston against which the downhole pressure works. The Williamson valve acordinglyshould require higher pressures to open, is subject two closing if these higher pressures are not maintained, and still oscillates.

According to one aspect of thins invention there is provided a mud saver valve, said valve comprising a tubular valve body with a first end adapted for attachment in fluid communicating relationship with a kelly, and a second endforattachment influid communicating relationship with a drill string,there being an annularseatwithin the interior of the valve body adjacent its first end and a tubular closure member reciprocally disposed within the valve body, the closure member being provided with a seating endforseating in said annularseattoeffect valveclosing,theotherend oftheclosuremember being open, the exterior of the closure member being provided with a portion comprising an annular expansion, means being provided constituting a seal between the annularexpansion and the interiorof said tubular valve body, means being provided to impart a resilient bias to the tubular body biasing the seating end into engagementwiththe annularseat, means also being providedtoconstraindownhole pressureto be applied onlytopartofthetubular closure member of lesser cross section than the cross section of said annular expansion.

According to another aspect of this invention there is provided a mud savervalveforpreventing drilling mud from escaping from a kellywhen a drill string is broken below the kelly, said valve comprising: a tubularvalve body having first and second ends, said first end being provided with means for attachment in fluid communicating relationship with the kelly, said second end being provided with means for attachment to said drill string; an annularseatfixed in the interior of said valve body adjacent its first end; atubularclosure memberwithin said valve body, said closure member being provided with a selectively closed seating end for seating in valve closing engagement with said annular seat, an open non-seating end in fluid communicating relationship with said drill string, and an annular expansion in the outer diameter of said closure member adjacent said seating end; a spacer ring disposed in sliding relationshiparoundsaidtubularclosuremember intermediate said annular expansion and said non-seating end of said closure member, said spacer ring and annular expansion cooperatively defining an annular chamber around said closure member, said spacer ring preventing downhole pressure from being communicated past said spacer ring; a helical spring disposed around said closure memberwithin said chamberfor biasing said closure member towards said annular seat; means carried by said valve body for preventing longitudinal displacement of saidspacerringtowardssaidannularexpansion; a first, annular, unidirectional seal disposed in substantially sealing engagement between said annular expansion flange and the interior annular wall ofsaid tubular valve bodyforpermitting fluid to pass out of said chamber but not into said chamber; a second, annular, unidirectional seal disposed around said closure member adjacent said non-seating end of said closure member and in substantially sealing engagement between the exterior of said closure member and the interior annularwall of said tubular valve body for permitting fluid to pass out of said chamber but not into said chamber; an opening in said closure member between said annular expansion and said seating end through which fluid may pass to the interior of said closure memberwhen said valve opens, against the bias of said helical spring; and means for selectively opening said seating end of said closure member in response to downhole pressure to vent said downhole pressure past said valve.

According to a further aspect of this invention there is provided a mud saver valve for preventing drilling mud from escaping from a kelly when a drill string is broken below the kelly, said valve comprising: atubularvalve body having firstand second ends, said first end being provided with meansforattachmentinfluid communicating relationship with the kelly, said second end being provided with means for attachment to said drill string; an annularseatfixed in the interior of said valve body adjacent its first end, a downhole face of said seat being bevelled to form an annular, inclined surface; a tubular closure member within said valve body, said closure member being provided with a selectively closed seating end for seating in valve closing engagement with said annular seat, an open end in fluid communicating relationship with said drill string, and an annularflange around said closure member adjacent said selectively closed end, a face of said closure member which seats against said annular seat being bevelled to form an annular inclined surface, the bevelled faces of said seat and closure member cooperatively forming an annular inclined surface along which said closure member and seat meet, said face of said closure member being comprised oftungsten carbide; a spacer ring disposed in sliding relationship around said tubular closure member intermediate said annularflange and said non-seating end of said closure member, said spacer ring and annularflange cooperatively defining an annularchamberaround said closure member, said spacer ring preventing down hole pressure from being communicated past said spacer ring and into said chamber; a snap ring carried by said valve body for preventing longitudinal displacement of said spacer ring towards said annularflange; a helical spring disposed around said closure memberwithin said chamber for biasing said closure membertowards said annular seat; a first, annular unidirectional seal disposed in substantially sealing engagement between said annularflange and the interior annular well ofsaidtubularvalve body for permitting fluid to pass out of said chamber but not into said chamber, said first unidirectional seal being mounted on and carried by said annularflange; a second annular, unidirectional seal disposed adjacent said non-seating end of said closure member and in substantially sealing engagement between the exteriorofsaid closure member and the interior annularwall of said tubularvalve body for permitting fluid to pass out of said chamber but not into said chamber, said second unidirectional seal being adjacent said spacer ring but outside said chamber; a pairofopposing openings in said closure member between said annularflange and said seating end through which fluid may pass to the interior of said closure memberwhen said valve is open; a tubular sleeve mounted within the seating end of said closure member, said sleeve being provided with a first open end in fluid communicating relationship with the interior of said closure member and a second open end in fluid communicating relationship with the exterior of said closure member through the seating end thereof, the inner diameter of said sleeve adjacent its first end being greaterthan the inner diameter of said sleeve adjacent its second end, said sleeve being retained in said closure memberwith a shear pin; and a spear assembly axially movably mounted in said sleeve for movement between a first position wherein said spear assembly sealingly engages said sleeve to slectively close said seating end and a second position wherein said seating end is open, said spear assembly comprising a central shaft surrounded by first and second spaced, substantially parallel annularstops, said first stop having a diameter at least as great asthe innerdiameter of said sleeve adjacent its second end, said first stop seating against said second end of said sleeve when said spear assembly is in its first position,the diameter of said second stop being greater than the inner diameter of said sleeve adjacent its second end but less than the inner diameter of said sleeve adjacent its first end for retaining said spear assembly in said sleeve when said spear is in said second position, said second stop being provided with openings through which downholefluid pressure is communicated to said first stop.

According to another aspect ofthis invention there is provided a mud savervalvefor preventing drilling mud from escaping from a kellywhen a drill string is broken below the kelly, said valve comprising; a tubularvalve body having a first dnd second end, said first end being provided with means for attachment in fluid communicating relationship with said kelly, said second end being provided with means for attachment to said drill string; an annular seat fixed in the interior of said valve body adjacent itsfirstend,a downholeface of said seat being bevelled to form an annular, inclined surface; a tubular closure memberwithin said valve body, said closure member being provided with a selectively closed seating end for seating in valve closing engagement with said annular seat, an open end in fluid communicating relationship with said drill string, and an annular expansion around said closure member adjacent said seating end, and an annular uphole face of said closure memberwhich seats against said annular seat being bevelled to form an annular inclined surface, the bevelled faces of said seat and closure member cooperatively forming an inclined surface along which said closure member and seat meet, said face of said closure member being comprised of tungsten carbide; afirst ring disposed in sliding engagement around said closure member adjacent said non-seating end of said closure member, an annular retainer adjacent said first ring and embedded in said valve body, and a second ring disposed in sliding engagement around said closure member on the side of said retainer opposite said first ring, said rings and annular expansion cooperatively defining an annular chamberaround said closure member, said first and second rings and embedded retainer preventing downhole pressure from being communicated past said rings and into said chamber; a helical spring disposed around said closure memberwithin said chamberfor biasing said closure membertowards said annular seat, said spring resting on said second ring; a pairofannular, unidirectional seals disposed in subtantiallysealing engagement between said annular expansion and the interiorannularwall of said tubularvalve body for permitting fluid to pass out of said chamber but not into said chamber, said pair of unidirectional seals being disposed between a pair of rings, one ring on either side of said pairof seals, said pair of rings being maintained in a stationary position buy a pair of retainer rings embedded in said valve body, said annular expansion of said closure member extending a sufficient longitudinal distance along said closure memberto maintain said pair of unidirectional seals in substantially sealing relationship with said annularexpansion, said pair of seals being stationary relative to said closure member; a downhole, annular unidirectional seal disposed adjacent said open end of said closure member and in substantially sealing engagement between the exterior of said closure member and the interior annularwall of said valve body for permitting fluid to pass out of said chamber but not into said chamber, said downhole seal being adjacentsaidfirst ring and outside said chamber, the inner diameter of said valve body being reduced between said down hole seal and said second end of said valve bodyto provide an annularflatshoulderon which said downhole seal rests; and opening in said closure member between said annular expansion and said seating end through which fluid may pass to the interior of said closure member when said valve is open; anda circular plate having a pluralityof depending, deformable legs for insertion into the seating end of said closure member, said deformable legs having enlarged ends for retaining said plate in axially sliding relationship with respect to said closure member, said plate being movable between a first position wherein said plate substantially sealingly closes the seating end of said closure member and a second position wherein said seating end is open, and an upwardly extending spear mounted on said plate and pointing towards said first end of said valve body, the area between the legs defining pressure release openingsthrough which pressure is vented to the surface, the annular bottom edge ofthe circular plate being inclined inwardly and downwardly, andthe annularsurface oftheclosurememberagainstwhichtheannular bottom edge ofthe closure plate seats is correspondingly inclined to provide an inclined seating surface along which the circular plate and closure member seal.

A preferred embodiment of the invention comprises a mud savervalve comprising a tubular valve body with a first end adapted for attachment in fluid communicating relationship with a kelly, and a second end adapted for attachment to a drill string.

Anannularseatisfixed in the interior ofthevalve body adjacent its first end. Atubular closure member is reciprocally disposed within the valve body, and the closure member is provided with a selectively closed seating end for seating in valve closing enagementwith the annularseat. The otherend of the closure member is open, and the closure member is provided with an annular expansion adjacentthe seating end. A pair of spacer rings is disposed in sliding relationship around the tubular body intermediate the annular expansion and the non-seating end of the closure member, the spacer rings being separated by a snap ring carried by the valve body.The rings and annular expansion cooperatively define an annular chamber aroundthe closure member, and the rings prevent downhole pressure from being communicated past the rings.

A helical spring is disposed around the closure memberwithinthe chamberfor biasing the closure membertowardstheannularseat.Afirstannular, unidirectional seal is disposed in sealing engagement between the annular expansion and the interiorannularwall ofthetubularvalve bodyfor permittingfluidto passoutoftheannularchamber but not into it.Asecond annular, unidirectional seal is disposed around the closure member adjacent its non-seating end for permitting fluid to pass out of the chamber but not into the chamber.

An opening is provided in the closure member between the annularexpansion andtheseating end through which fluid may pass to the interior ofthe closure memberwhen the valve is open. Means is also provided for selectively opening the seating end ofthe closure member in response to excessive downhole pressure to vent the down hole pressure past the valve.

In preferred embodiments, the means for selectively opening the seating end of the closure member is a spear assembly axially movably mounted in the closure memberfor movement between an open position and a closed position. In especially preferred embodiments, the spear is comprisedofan uprightspearmountedon aflat plate which has deformable depending legs which fit within the open seating end of the closure member.

The spear assembly can be removed from the closure member by pulling upwardly on the spear with conventional wireline tools, thereby inwardly deforming the depending legs, and resulting in removal ofthe spear from closure member.

Similarly, the spear assembly can be reinserted in the closure member by deforming the depending legs inwardly until they are once again within the closure member.

In especially preferred embodiments, the unidirectional seal around the annular expansion of the closure member is held stationary by a pair of snap rings carried by the valve body. The annular expansion is thereby protected which the valve is in its open position because the annular expansion is contained within the annular chamberwhen the valve is open. This prevents exposure ofannular expansion to theturbulent and abrasive flow of the drilling mud, thereby protecting the structural integrity ofthe closure member and preventing erosion of the surface of the annular expansion.

In orderthatthe invention may be more readily understood, so that furtherfeatures thereof may be appreciated, the invention will now be described byway of example with reference to the accompanying drawings, in which: Figure lisa side elevational view of a valve in accordancewiththe invention, partially in cross section, the closure member being shown in the closed position with the spear assembly in an open position forventing downhole pressure past the valve, Figure 2 is a view sim ila rto Figure 1 wherein the closure member is in an open position for permitting drilling mudto be introduced into the drill string,the spear assembly being closed, Figure 3 is an enlarged, exploded view of the spear assembly and the sleeve in which it fits, the shear pins which retain the sleeve within the closure member also being shown, Figure 4is an enlarged, fragmentary cross-sectional view of the closure member, the spear assembly being shown in its selectively closed position, the attachment of a wireline tool to the spear assembly being shown in phantom, Figure 5is a side elevational view of a second embodiment ofthe invention, parts of the tool being shown in cross section for clarity, the valve being shown in an open condition and the spear assembly being shown in a closed condition, Figure 6 is an enlarged, fragmentary view of the annularchamber between the seals in Figure5, Figure 7 is a perspective view of the seating end of the closure member showing the spear assembly removed from the closure member, and Figure 8 is a cross sectional view the closure member shown in Figure 7, the spear assembly in its removed condition being shown in phantom.

Afirstembodimentofthetool, shown in Figures 1 to 4, comprises a mud saver valve 10 for preventing drilling mud from escaping from a kelly (not shown) when a drill string (not shown) is broken belowthe kelly. Valve 10 comprises a tubularvalve body 12 having a first end 14 provided with internal threads for attaching first end 14 in fluid communicating relationship with the kelly. Body 12 is also provided with second end 16,which is externallythreaded to providea meansforattaching body12tothe internallythreaded drill string.

An annularseat 18 is fixed in the interior of body 12 adjacent its first end 14, a downhole face 20 of annular seat 18 being bevelled to form an annular, inclined surface.

Atubular closure member 22 is slidingly disposed within body 12, closure member 22 being provided with a selectively closed seating end 24 for seating in valve closing engagement with annularseat 18.

Closure member 22 is also provided with an open iower end 26 which establishesfluid communicating relationship between the interior of closure member 22 and the drill string. An annularflange 28 is disposed around closure member 22 adjacent seating end 24.

An upper face 30 of closure member 22 which seats againstannularseat 18 is bevelled to form an annular inclined surface, the bevelled face 20 of annularseat 18 and bevel led face 30 of closure member 22 cooperatively forming an annular inclined surface alongwhich closure member22 and annular seat 18 meet. In preferred embodiments, face 30 is comprised oftungsten carbideto provide an especially wear resistant surface which will withstand the wear of repeated opening and closing of the valve, as well as the erosive influence ofthe turbulent flow of the drilling mud past end 24.

A pair of spacer rings 32,33 is disposed in sliding relationship around closure member 22 intermediate annularflange 28 and non-seating open end 26 of closure member22. Spacer rings32, 33 and annular flange 28 cooperatively define an annular chamber 34 around closure member 22, spacer rings 32,33 being designed to prevent down hole pressure from being communicated past spacer rings 32,33 and into chamber 34.A snap ring orcirclip 36 is inserted into an indentation in the interior wall 42 of body 12 so that snap ring 36 is carried by body 12, thereby preventing longitudinal displacement of spacer ring 32towards annularflange 28.A helical spring 38is disposed around closure member 22 within chamber 34 for biasing closure member 22 towards the annular seat 18 to maintain valve 10in a normally closed position, the spring 38 also exerting tension against spacer ring 33 to hold it against snap ring 36.

Afirst, annular unidirectional seal 40 is disposed in substantially sealing engagement between annular flange 28 and the interior annularwall 42 of body 12 for permitting fluid to pass out of chamber 34 but not into chamber 34. Seal 40 is mounted within an annular indentation in flange 28, and is carried by flange 28 in the first embodimentof the invention shown in Figures 1 to 4.

Asecond annular, unidirectional seal 44is disposed adjacentthe non-seating open lower end 26 of closure member 22 and in substantially sealing engagement between the exterior of closure member 22 and the interiorannularwall 42 of body 12 for permitting fluid to pass out of chamber34 but not into chamber34,the second seal 44 being adjacent spacer ring 32 but outside chamber 34.

A pair of opposing openings 46,48 are provided in closure member 22 between annuiarflange 28 and seating end 24 through which fluid such as drilling mud may passto the interior50 of closure member 22 when valve 10 is in the open position shown in Figure 2. The arrows in Figure 2 indicate the flow path of drill mud.

Atubularsleeve 52 (bestshown in Figures 3 and 4) is mounted within the seating end 24 of closure member 22, sleeve 52 being provided with a first open end 54 in fluid communicating relationship with the interior of closure member 22 and a second open end 56 in fluid communicating relationship with the exterior of closure member 22 through seating end 24. The inner diameter of sleeve 52 adjacent its first end 54 is greater than the inner diameter of sleeve 52 adjacent its second end 56. In the preferred embodiment shown in Figures 1 to 4, there are only two inner diameters in sleeve 52, afirst inner diameter adjacent end 54, and a second, smaller inner diameter adjacent end 56. Sleeve 52 is retained in closure member 22 by means of shear pins 58,60 as shown in Figure 4.

Aspearassembly62 (shown in isolation in Figure 3) is axially movably mounted within sleeve 52 for movement between a first position (shown in Figures 2 and 4) wherein said spear assembly 62 sealingly engages sleeve 52 to selectively close seating end 54 and a second position (shown in Figure 1) wherein seating end 24 is open. Spear assembly 62 comprises a central shaft 64 surrounded by a first annular stop 66 and a second annular stop 68, said stops 66,68 being in spaced, substantially parallel relationship to one another.

First stop 66 has a diameter at least as great as the inner diameter of sleeve 52 adjacent its second end 56, first stop 66 seating against the second end 56 of sleeve 52 when spear assembly62 is in itsfirst, closed position as shown in Figure 2. The diameter of second stop 68 is greaterthan the inner diameter of sleeve 52 adjacent its second end 56, but the diameter of second stop 68 is less than the inner diameter of sleeve 52 adjacent its first end 54. This relationship retains spear assembly 62 in sleeve 52 when spear assembly 62 is in its second, open position shown in Figure 1. Second stop 68 is provided with openings 70 (Figure 3) through which downholefluid pressure is communicated to first stop 66.

In operation, internally threaded end 14 of body 12 is attached to an externallythreaded portion ofthe kelly, and externally threaded second end 16 of body 12 is threaded into an internally threaded end of a drill string. As drilling mud is pumped through the kelly into valve 10, the hydraulic force of the drilling mud above body 12 increases. Spacer rings 32,33, which are held in position by snap ring 36, cooperatively prevent downhole pressurefrom being exerted against any portions of closure member 22 exceptforan area equivalenttothe outside diameter of open end 26 of closure member 22. The uphole pressure, however, can act against an area substantially equal to the outside diameter of annularflange 28.This means that uphole pressure acts against a greater surface area than downhole pressure, and since force is a function of hydraulic pressure multiplied times area, the effective uphole force acting to open valve 10 is effectively magnified relative to the downhole force, resulting in an easier opening ofthe valve and more reliable maintaining ofthe valve in the open position. The pressure ofthe drilling mud in the vicinity of the tool is usually approximately 2500 psi, which results in the valve opening quickly and staying solidly open until drilling is stopped. Since opening ofthevalve relies on hydraulicforce instead of the flow of the velocity ofthe drilling mud, the valve will not oscillate in responsetovariationsinflowfrom duplexortriplex pumps.This represents a significant advance over the art represented by the prior patents such as the patents of Hilliard and Parker et al discussed above which disclose valves which open in response to the flow of mud. Absence of oscillations in responseto variations in flow gives a longer life to the tool since the sealing surfaces of the tool are not being worn away by constant oscillation.

The hydraulicforce moves closure member 22 from the position shown in Figure 1 against the bias of spring 38 to the position shown in Figure 2.

Drilling mud is then abletoflowin the direction of the arrows in Figure 2through annular seat 18, past face 30 and into openings 46,48 of closure member 22, thence to the interior 50 of closure member and out of open end 26 on its wayto the drill string. When the drill string has been driven into below the surface, introduction of drilling mud is terminated, and the absence of uphole hydraulic force permits closure memberto smoothly, quickly and firmly move with the bias of spring 38 back into the sealing position shown in Figure 1. The uphole static hydraulic pressure is insufficient to open closure member 22 against the bias of the spring 38, and the seal is maintained.It should also be notedthatthe bevelled faces 20, 30 seal along an inclined plane, thereby providing a much better seal than those prior art devices which employ a flat, annularseat and flat upper face on the closure member.

Pressure belowvalve 10 is communicated above the valve through spear assembly 62, which allows the drillerto read a blowoutthrough the drill pipe, eliminates the possibility of trapped pressure, and allows the drill to reverse circulate. When downhole pressure is encountered, it is communicated through openings 70 and second step 68 to first stop 66, thereby moving spear assembly 62 from the closed position shown in Figures 2 and 4to the open position shown in Figure 1. Downhole pressure is then vented through openings 70.

Spear assembly 62 is provided with a spearhead so that conventional wireline tools can be inserted into the valve and attached to the spearhead. An upward force exerted on the wirelinetool (shown in Figure 4) can then break shear pins 58,60 so that sleeve 52 is removed from closure member 22. The shearing operation is only required on those occasions when it is necessary to run wirelinetools past closure member 22, and valve 10can be made operational again by reinserting shear pins 58,60.

In a second embodiment ofthe invention shown in Figures 5to 8, several additional problems with prior art tool have been overcome. A mud savervalve80 is shown in FigureSforpreventingdrillingmudfrom escaping from a kelly when a drill string is broken below the kelly. Valve 80 comprises a tubularvalve body 82 having a first open end 84 which is internally threaded for connection to a kelly, and a second open end 86 which is externally threaded for connection in fluid communicating relationship with a drill string.

An annularseat88 is fixed in the interiorofvalve 80 adjacent first end 84, a downholeface 90 of seat 88 being bevelled to form an annular, inclined surface.

Atubular closure member 92 is disposed within valve body 82, and is provided with a selectively closed seating end 94for seating in valve closing engagement with annular seat 90. Closure member 92 is also provided with an open end 96 in fluid communicating relationship with the drill string, and an annularexpansion 98 around the closure member 92 adjacent the seating end 94. An annular uphole face 100 of closure member 92 is bevelled to form an annular inclined surface, the bevelled face 90 of seat 88 and bevelled face 100 of closure member 92 cooperatively forming an inclined surface along which closure member 92 and seat 88 meet, thereby forming a more positive seal when the valve is in a closed position.Face 100 of closure member 92 is, in preferred embodiments, comprised oftungsten carbideto provide a longer wearing surface.

Afirstspacerring 102 is disposed in sliding engagement around closure member 92 adjacent its non-seating open end 96, and an annular retainer 104fits into an indentation in the interiorwall 106 of body 82 to retain ring 102 in position. A second spacer ring 108 is disposed in sliding engagement around closure member 92 on the opposite side of retainer 1 04 fro m first spacer ring 102, and is also retained in position thereby. Spacer rings 102,108 and annularexpansion 98 cooperativelydefine an annular chamber 1 10 around closure member 92.

The purpose of first and second spacer rings 102,108 is, as in the first embodiment, to prevent downhole pressure from being communicated pastthem.

A helical spring 112 is disposed around closure member92within chamber 110forbiasing closure member 92 towards annuiar seat 88 to maintain valve 80 in a normally closed position. Spring 112 rests, in the preferred embodiment shown in Figures 5to 8, on the second spacer ring 108.

Apairofannular, unidirectional seals 114,1 16 are disposed in substantially sealing engagement between annular expansion 98 and interior annular wall 106 of body 82 for permitting fluid to pass out of chamber 110 but not into chamber 110.

Unidirectional seals 114, 116 are disposed between a pair of rings 119, 120, one ring on either side of seals 114,116. Rings 118,120 are maintained ion a stationary position by a pair of retainer rings 122, 124 mounted in indentations in interiorwall 104. Annular expansion 98 extends a sufficient longitudinal distance along closure member 92 to maintain seals 114, 116 in substantially sealing relationship with annular expansion 98. In otherwords, annular expansion 98 is in contact with seals 114,116 along the full range of compression of closure member 92 against the bias of the spring 112.

A downhole, annular unidirectional seal 126 is disposed adjacent open end 96 of closure member 92 and in substantially sealing engagement between the exterior of closure member 92 and the interior of annularwall 106 for permitting fluid to pass out of chamber 110 but not into chamber 110. Downhole seal 126 is adjacentfirst ring 102 and outside chamber 110, the inner diameter of valve body 82 being reduced between downhole seal 26 and second end 86 ofbody82to provideashoulderl28 on which downhole seal 126 rests.

Apairofopposing openings 129,131 are located in closure member 92 between annular expansion 98 and seating end 94to provide orifices through which fluid, such as drilling mud, may passto the interiorof closure member92 when valve 80 is open.

Acircularplate 132 is provided and hasfour identical, depending, deformable legs 134 adapted for insertion into seating end 94 of closure member 92. The deformable legs are made of a malleable yet resilient material such as steel or aluminium, and legs 134are provided with enlarged heads 136 for retaining plate 132 in axially sliding relationship with respect to closure member 92. Plate 132 is movable between a first position, shown in Figures 5 and 8, wherein plate 132 substantially sealingly closes seating end 94Of closure member 92 and a second position (not shown in the drawings) wherein seating end 94 is open as a result ofthe axial movement of plate 132 upwardly and away from seating end 94 in response to downhole pressure.An upwardly extending spear 138 is mounted fixedly on plate 132 and points toward first end 84 ofvalve body 82.

In operation, valve 80 functions in a similarfashion to the first embodiment described above. The primary differences in operation, however, are that annular expansion 98 moves against stationary seals 114,116, as opposed to the first embodiment wherein the annular expansion carried the seals. The advantage of providing stationary seals and a movable annular expansion isthatwhenclosure member 92 opens against the bias of the spring (as shown in Figure 5) annular expansion 98 moves into chamber 110, and is thereby protected from the turbulent, abrasiveflowofthe drilling mud. This is an advantage since the turbulent, abrasive flow of the drilling mud would otherwise wear away the sealing surface on annular expansion 98. Retooling and repair of the sealing surface is usually one ofthe most expensive and time consuming problems with prior artvalves. Accordingly, making the seals stationary against a movable annular expansion is a remarkable advance in and of itself.

The spear and plate with deformable legs also differ from the spear assembly 62 in the first embodiment. The plate with deformable legs makes it possibleto eliminatesleeve 52 and shear pins 58, 60 because plate 132 can be attached directly to closure member 92 by inwardlydeforming legs 134 to fit them inside seating end 94 of closure member 92. Enlarged heads 136 then retain plate 132 in axially movable relationship within closure member 92 and seating end 94 is provided with a reduced diameter portion that retains heads 136 within closure member92. Enlarged heads 136 also hold legs 134 in a substantially vertical position, which allows them to slide freely in and out ofthe reduced diameter portion of seating end 94.When it becomes necessaryto remove plate 132,wireline tools grasp spear 138, and an upward pull ofsufficientforce inwardly deforms legs 134to permit plate 132 and its associated parts to be removed from closure member 92. Reinsertion of plate 132 into closure member 92 is easily accomplished by inwardly deforming legs 134untilenlarged heads136fitinto seating end 194.

This invention thus provides a kelly mud saver value having a reciprocating closure member provided with first and second unidirectional seals which define the ends ofan annularchamberaround a closure member. The unidirectional seals permit fluid to leave the annular chamber but not enter it, thereby permitting the closure memberto open and close in responsetohydraulicforceinthesystem instead of in response to the force of the velocity of mud flow.

The invention also provides such a valve with a stationarysnap ring carried by the tubular valve body which surrounds the closure member. This snap ring prevents downhole pressure from being communicated to the reciprocal closure member, thereby reducing the surface area against which the downhole pressure is exerted. As a result, lower uphole pressure is required to open the closure member, and once open the closure member stays more firmly in the open position.

The invention further provides, in certain embodiments, a spear assembly axially movably mounted within the closure member for venting excessive down hole pressure past the valve. In especially preferred embodiments, the spear assembly is held within the closure member by a plurality of deformable legs which permit the spear to be selectively inserted or removed from the closure memberwithout the necessity for repairing the spear assembly in a shop.

The invention additionally provides embodiments in which the body of the closure member is protected fromturbulentflowofabrasivedrilling mud when the valve is in an open position.

Claims (29)

1. Amud savervalve, said valve comprising a tubularvalve body with a first end adapted for attachment in fluid communicating relationship with a kelly, and a second endforattachmentinfluid communicating relationship with a drill string,there being an annular seat within the interior of the valve body adjacent its first end and a tubular closure member reciprocally disposed within the valve body, the closure member being provided with a seating endforseating in said annularseatto effect valve closing, the other end of the closure member being open, the exterior ofthe closure member being provided with a portion comprising an annular expansion, means being provided constituting a seal between the annular expansion and the interior of saidtubularvalve body, means being provided to impart a resilient bias to the tubular body biasing the seating end into engagement with the annular seat, means also being provided to constrain down hole pressure to be applied onlyto part of the tubular closure member of lesser cross section than the cross section of said annularexpansion.

2. Avalve according to claim 1 wherein said seating end ofthe closure member is selectively closable.

3. Avalve according to claim 1 or2whereinthe first end of the tubular closure member being bevelled to form an inclined surface, the seat also being bevel led so that the inclined su rface seali ngly engages said seat when the valve is closed.

4. Avalveaccordingtoclaim 1 orclaim2wherein a first annular unidirectional seal is disposed in sealing engagement between the annular expansion and the interiorwall ofthetubularvalve body for permitting fluid to pass out of an annular chamber defined between said annular expansion, and additional sealing means located intermediate said annular expansion and the non-seating end ofthe closure member, said additional sealing means comprising a unidirectional seal for permitting fluid to pass out of said chamber but not into the chamber.

5. Avalve according to anyone ofthe preceding claims wherein an opening is provided intheclosure member between the annular expansion and the seating end through which fluid may passto the interioroftheclosurememberwhenthevalveis open.

6. Amudsavervalveforpreventing drilling mud from escaping from a kelly when a drill string is broken below the kelly, said valve comprising: a tubularvalve body having first and second ends, said first end being provided with means for attachment in fluid communicating relationshipwiththekelly, said second end being provided with means for attachmentto said drill string; an annularseatfixed in the interior of said valve body adjacent its first end; a tubular closure member within said valve body, said closure member being provided with a selectively closed seating end for seating in valve closing engagement with said annular seat, an open non-seating end in fluid communicating relationship with said drill string, and an annular expansion in the outer diameter of said closure member adjacent said seating end; a spacer ring disposed in sliding relationship around said tubular closure member intermediate said annular expansion and said non-seating end of said closure member, said spacer ring and annular expansion cooperatively defining an annular chamber around said closure member, said spacer ring preventing downhole pressure from being communicated past said spacer ring; a helical spring disposed around said closure member within said chamber for biasing said closure member towards said annularseat; means carried by said valve body for preventing longitudinal displacement of said spacer ring towards said annular expansion; a first, annular, unidirectional seal disposed in substantially sealing engagement between said annularexpansionflangeandtheinteriorannular wall of said tubular valve bodyfor permitting fluid to pass out of said chamber but not into said chamber; a second, annular, unidirectional seal disposed around said closure member adjacent said non-seating end of said closure member and in substantially sealing engagement between the exterior ofsaid closure member and the interior annularwall ofsaidtubularvalvebodyforpermitting fluid to pass out of said chamber but not into said chamber; an opening in said closure member between said annular expansion and said seating end through which fluid may pass to the interior of said closure member when said valve opens, against the bias of said helical spring; and means for selectively opening said seating end of said closure member in response to downhole pressure to vent said down hole pressure past said valve.

7. The valve of claim 6, wherein said meansfor selectively opening said seating end comprises; a tubular sleeve mounted within the seating end of said closure member, said sleeve being provided withafirstopen end influid communicating relationship with the interior of said closure member and a second open end in fluid communicating relationship with the exterior of said closure member through the seating end thereof, the inner diameter ofsaid sleeve adjacent its first end being greater than the inner diameter of said sleeve adjacent its second end;; andaspearassemblyaxially movably mounted in said sleeve for movement between a first position wherein said spear assembly substantially sealingly engages said sleeve to selectively close said seating end and a second position wherein said seating end is open.

8. The valve of claim 7, wherein said spear assemblyfurther comprises a central shaft surrounded by first and second spaced, substantially parallel annular stops, said first stop having a diameter at least as great as the inner diameter of said sleeve adjacent its second end, said first stop seating against said second end of said sleeve when said spear assembly is in its first position,the diameter of said second stop being greaterthan the inner diameter of said sleeve adjacent its second end but less than the diameter of said sleeve adjacent its first end for retaining said spear assembly in said sleeve when said spear assembly is in said second position, said second stop being provided with openings through which downhole fluid pressure is communicated to said first stop.

9. The valve of claim 8, wherein said sleeve is retained in said closure member with a shear pin.

10. The valve of any one of claims 6 to 9wherein an annularface of said annular seat against which said closure member seats is bevelled, and an annularface of said seating end of said closure memberwhichseatsagainstsaidannularseatis cooperatively bevelled so that said faces seat along an annular inclined surface.

11. Thevalveofclaim 10whereinsaidfaceof said seating end is comprised oftungsten carbide.

12. The valve of any one of claims 6to 11 wherein said annular expansion of said closure member is an annularflange.

13. Thevalveofclaim 12 wherein said first unidirectional seal is disposed around and carried by said annularflange.

14. Thevalveofclaim 13 wherein said second unidirectional seal is disposed around said closure member adjacent said spacer but putside said chamber.

15. The valve of claim 14whereintheinner diameter of said valve body is reduced between said second unidirectional seal and said second end of said valve body to form a reduced diameter portion, said reduced diameter portion providing a shoulder on which said second unidirectional seal rests.

16. The valve of claim 15 wherein said means for preventing displacement of said spacer towards said annularflange is a snap-ring carried by said valve body.

17. Amudsavervalveforpreventing drilling mudfrom escaping from a kellywhen a drill string is broken below the kelly, said valve comprising: a tubularvalve body having first and second ends, said first end being provided with means for attachment in fluid communicating relationship with the kelly, said second end being provided with meansfor attachment to said drill string; an annularseatfixed in the interior of said valve body adjacent its first end, a downholeface of said seat being bevelled to form an annular, inclined surface; atubularclosure memberwithin said valve body, said closure member being provided with a selectively closed seating end for seating in valve closing engagement with said annularseat, an open end in fluid communicating relationship with said drill string, and an annularflange around said closure member adjacent said selectively closed end, a face of said closure memberwhich seats against said annular seat being beveiled to form an annu lar inclined surface, the bevelled faces of said seat and closure membercooperativelyforming an annular inclined surface along which said closure member and seat meet, said face of said closure member being comprised oftungsten carbide; a spacer ring disposed in sliding relationship around said tubular closure member intermediate said annularflange and said non-seating end of said closure member, said spacer ring and annularflange cooperatively defining an annular chamber around said closure member, said spacer ring preventing downhole pressure from being communicated past said spacer ring and into said chamber; a snap ring carried by said valve body for preventing longitudinal displacement of said spacer ring towards said annularflange; a helical spring disposed around said closure member within said chamberfor biasing said closure member towards said annular seat; a first, annular unidirectional seal disposed in substantially sealing engagement between said annularflangeandtheinteriorannularwell of said tubular valve body for permitting fluid to pass out of said chamber but not into said chamber, said first unidirectional seal being mounted on and carried by said annularflange; a second annular, unidirectional seal disposed adjacent said non-seating end of said closure member and in substantially sealing engagement between the exterior of said closure member and the interior annularwall of said tubular valve body for permitting fluid to pass out of said chamber but not into said chamber, said second unidirectional seal being adjacent said spacer ring but outside said chamber; a pair of opposing openings in said closure member between said annularflange and said seating end through which fluid may passtothe interior of said closure member when said valve is open; atubularsleeve mounted within the seating end of said closure member, said sleeve being provided with afirstopen end in fluid communicating relationship with the interior of said closure member and a second open end in fluid communicating relationship with the exterior of said closure memberthrough the seating end thereof, the inner diameter of said sleeve adjacent its first end being greaterthantheinnerdiameterofsaidsleeve adjacent its second end, said sleeve being retained in said closure memberwith a shear pin; and a spear assembly axially movably mounted in said sleeve for movement between a first position wherein said spear assembly sealingly engages said sleeve to slectively close said seating end and a second position wherein said seating end is open, said spear assembly comprising a central shaft surrounded by first and second spaced, substantially parallel annularstops, said first stop having a diameter at least as great as the inner diameter of said sleeve adjacent its second end, said firststop seating against said second end of said sleeve when said spear assembly is in its first position, the diameter of said second stop being greaterthan the inner diameter of said sleeve adjacent its second end but less than the inner diameter of said sleeve adjacent its first end for retaining said spear assembly in said sleeve when said spear is in said second position, said second stop being provided with openings through which downholefluid pressure is communicated to said first stop.

18. Thevalveofclaim 17 wherein said means for selectively opening said seating end comprises a circular plate having a plurality of depending, deformable legs for insertion into the seating end of said closure member, said deformable legs having enlarged ends for retaining said plate in axially sliding relationship with respect to said closure member, said plate being movable between a first position wherein said plate substantially sealingly closes the seating end of said closure member and a second position wherein said seating end is open.

19. Thevalveofclaim 18whereinsaid plateis provided with an upwardly extending spear pointing in the direction of said first end of said valve body.

20. Thevalveofclaim 19, wherein an annular face of said annular seat against which said closure member seats is bevelled, and an annularface of said seating end of said closure memberwhich seats against said annular seat is cooperatively bevelled so that said faces seat along an annular inclined surface.

21. The valve of claim 20wherein said face of said seating end is comprised oftungsten carbide.

22. Thevalveofclaims 17to21 whereinsaidfirst unidirectional seal is maintained in a stationary position by means carried by said valve body, and said annular expansion of said closure member extends over a sufficient length of said closure member to maintain said first unidirectional seal and said annular expansion in substantially sealing relationship as said closure member moves between a seating position and a non-seating position with said annular seat.

23. The valve of claim 22 wherein said second unidirectional seal is disposed around said closure member adjacent said spacer ring but outside said chamber.

24. The valve of claim 23 wherein the inner diameter of said valve body is reduced between said second unidirectional seal and said second end of said valve body thereby forming a reduced diameter portion, said reduced diameter portion providing a shoulder on which said second unidirectional seal rests.

25. Thevalveofclaim 24whereinsaidspacer ring is comprised of a first ring disposed in sliding engagement around said closure member adjacent said second unidirectional seal, an annular retainer adjacent said first ring and carried by said valve body, and a second ring disposed in sliding engagement around said closure member between said retainer and helical spring and on which said helical spring rests.

26. A mud savervalve for preventing drilling mudfrom escaping from a kellywhena drill string is broken below the kelly, said valve comprising; a tubularvalve body having a first and second end, said first end being provided with means for attachment in fluid communicating relationship with said kelly, said second end being provided with means for attachment to said drill string; an annular seat fixed in the interior of said valve body adjacent its first end, a down hole face of said seat being bevelled to form an annular, inclined surface; a tubular closure memberwithin said valve body, said closure member being provided with a selectively closed seating end for seating in valve closing engagement with said annular seat, an open end in fluid communicating relationship with said drill string, and an annular expansion around said closure member adjacent said seating end, and an annular uphole face of said closure memberwhich seats against said annu lar seat being bevelled form an annular inclined surface, the bevelled faces of said seat and closure member cooperatively forming an inclined surface along which said closure member and seat meet, said face of said closure member being comprised of tungsten carbide; a first ring disposed in sliding engagement around said closure member adjacent said non-seating end of said closure member, an annular retainer adjacent said first ring and embedded in said valve body, and a second ring disposed in sliding engagement around said closure member on the side of said retainer opposite said first ring, said rings and annular expansion cooperatively defining an annular chamberaround said closure mernber, said firstand second rings and embedded retainer preventing down hole pressure from being communicated past said rings and into said chamber; a helical spring disposed around said closure member within said chamberfor biasing said closure member towards said annular seat, said spring resting on said second ring; a pair of annular, unidirectional seals disposed in substantially sealing engagement between said annular expansion and the interior annularwall of said tubularvalve body for permitting fluid to pass out of said chamber but not into said chamber, said pair of unidirectional seals being disposed between a pair of rings, one ring on either side of said pair of seals, said pair of rings being maintained in a stationary position by a pair of retainer rings embedded in said valve body, said annular expansion of said closure member extending a sufficient longitudinal distance along said closure member to maintain said pair of unidirectional seals in substantially sealing relationship with said annular expansion, said pair of seals being stationary relative to said closure member; a downhole, annular unidirectional seal disposed adjacent said open end of said closure member and in substantially sealing engagement between the exterior of said closure member and the interior annularwall of said valve body for permitting fluid to pass out of said chamber but not into said chamber, said downhole seal being adjacent said first ring and outside said chamber, the inner diameter of said valve body being reduced between said downhole seal and said second end of said valve bodyto provide an annularflat shoulder on which said downhole seal rests; an opening in said closure member between said annular expansion and said seating end through which fluid may pass to the interior of said closure memberwhen said valve is open; and a circular plate having a plurality of depending, deformable legs for insertion into the seating end of said closure member, said deformable legs having enlarged ends for retaining said plate in axially sliding relationship with respect to said closure member, said plate being movable between a first position wherein said plate substantially sealingly closes the seating end of said closure member and a second position wherein said seating end is open, and an upwardly extending spear mounted on said plate and pointing towards said first end of said valve body,the area between the legs defining pressure release openings through which pressure is vented to the surface, the annular bottom edge ofthe circular plate being inclined inwardly and downwardly, and the annular surface oftheclosurememberagainstwhichtheannular bottom edge of the closure plate seats is correspondingly inclined to provide an inclined seating surface along which the circular plate and closure member seal.

27. A mud saver valve substantially as herein described with reference to and as shown in Figures 1 to4oftheaccompanying drawings.

28. A mud saver valve substantially as herein described with reference to and as shown in Figures 5to 8 ofthe accompanying drawings.

29. Any novel feature or combination offeatures disclosed herein.