US3552412A

US3552412A - Drill string dump valve

Info

Publication number: US3552412A
Application number: US676409A
Authority: US
Inventors: Donald K Hagar; Joseph L Pekarek
Original assignee: Donald K Hagar; Joseph L Pekarek
Current assignee: Chevron USA Inc
Priority date: 1967-10-19
Filing date: 1967-10-19
Publication date: 1971-01-05
Anticipated expiration: 1988-01-05

Abstract

The invention comprises an improved drill string dump valve comprising a moveable member having a downwardly and outwardly sloping sealing surface. The valve comprises structure to permit the moveable member with its operating member thereon to fall free and unrestricted downwardly away from the relief ports.

Description

United States Patent Inventors Dona d s z 2,196,658 4/1940 Burt l66/l94X Jo ep L- t a i 2,493,650 1/1950 Baker et a]... 166/224X Appl. No- 6 2,659,438 11/1953 Schnitter..... 166/222X Filed Oct-1 ,1 2,651,367 9/1953 Baker 166/194 Patented .lan.5, 1971 3,013,612 12/1961 Angel 137/68X Primary Examiner-William F. ODea DRILL STRING DUMP VALVE Assistant Examiner-Richard Gerard 6 Claims, 5 Drawing Figs. Attorneys-Meyer Neishloss, Deane E. Keith and William u.s. c1. 137/10, Wmky 166/194 Int. Cl F16k 31/00 Field of Search l37/68,70, ABSTRACT; The invention comprises an improved drill string 166/ 154, I94. 224(lnq r l75/237,3l8 dump valve comprising a moveable member having a downwardly and outwardly sloping sealing surface. The valve References cmd comprises structure to permit the moveable member with its UNITED STATES PATENTS operating member thereon to fall free and unrestricted 602,378 4/1898 Thomson 285/2X d wnwardly awayfrom the reliefports.

2 1 l i i l 1 :11; l 1 ii] 2 l 1 j I1 ,1 I 20 3 l /a 1 '1" 1 1 1 1 l; y l H I I /0 a0 l 36 l 34 2 7 1 2 7 111] i ll 1 l 44 2 w '50 42a 76' 1 :56 .l laljf 32 M 32 5 1 I l E PATEN'TEDJ N 5197: 3552.412

. I SHEET 2 [1F 2 INVENTORS. DOA/4L0 K. HAG/1R JdSfPH L. PE/(AREK a pipe or the like;

' addition of: single rqi lle'd,

More particularly, the invention'is directed to a dump valve for. use with a string of drill pipe. In'drilling wells in the earth by the almostuniversallyused rotary method, a long string of pipe carrying adrill bit at its lower end is utilized. Special fluids, commonly called fdrilling. mud, {are circulated down Another disadvantage of these prior sleeve type dump valves is that the shorter the sleeve is, the more it is likely to cock and thereby not move properly, and the longer the sleeve the. drill pipe, through the bit,. "onto the bottom of the i; borehole, and up through the annulus between'the drill pipe and the borehole. The mud serves as a coolant, as a carrier to carry the chips or cuttings tothe surface, as a weight to hold I formation fluids in place to prevent a "blowout of the well,

and other purposes well known to those skilled in theart.

The present invention .provides a highly reliable dump valve. A dump valve is desirable because for certainpurposes the fluid enit passages inthe bit do not permit a rapid enough flow of mud therethrough. For example, the problem arises when it is desiredto'pump certain welltreating materials, such as lost circulationgmateiials, intothe borehole and the formation at a rate greaterthanthat which canbe obtained if these materials were. pumped through the openings in. the bit. Additionally, some lost circulationmaterials may be too large to pass through thebit openings.

Another time the problem arisesis whena'w ell is or is about to .blow out. In such case', it is necessary to increase the hydraulicpressure Qof the. mudin the well as fast as possible.

With the relatively small normal openings in the bit, it may not i be possible to get a heavier mud in 1 or prevent the blowout.

the well fastenough to stop Another purposeof a'dump valve concerns the normally occurring periods when'it is desired to make a round trip." A round trip is aterrn of theartwhich means removal of the entire drill string'fromthe well and-then replacing it- This is done by taking the drill string apart in joints of one, two, or three sections of drill. pipe e-ach, depending on other conditions. A trip'must'be made many times during the drilling of a normal well for purposes of changing the 'bit, to set an intermediate string of casing, to run a drillstem test, to run a coring tool to obtain cores, and for other purposes well known to those skillcdin the arLAs is wellunders'tood, the drill string is continuously lengthened as the well-is drilled by the periodical making 3 l l g e wellwith any" of 1 the various welhtreating materials, it is highlydesirable to provide an enlarged opening or openings at the lower end of the drill string to facilitaterapid removal of the column of mud In prior dump valves, a moveable valve member was provided. usually in the-form of a cylindrical'member or sleeve, which was movcd downwardly to uncover relief openings having various configurations-Such cylindrical or sleeve type dumpvalves suffer from several disadvantages whichare ov'ercome by the present invention-Since the surface of contact sections of drillpipe at ihe upper end, as

is, the more the surfaces between which'particles may wedge are enlarged. Wedged particles can result in the sleeve not moving properly or not moving at all. Another disadvantage of the sleeve type is that a part of each sheared pin or bolt moves with the cylinder and can damage the inside surface of the valve and/or the sealing means, which necessitates rework of the valve. The frequency of malfunctions in sleeve type dump valves is unacceptably high, and the useful life is unacceptably .short due to wearing parts, particularly where there is a signifi cant concentration of particulate matter in the mud.

Another priortype of dumpvalve utilizes pressure differential means. In these valves, Il'lG'I/QIVE is normally open 1 and closes only when the drill string is pressurized. The disadvantages of this type of valve include permitting entry of well fluids and relatively large entrained cuttings into the drill string as it is lowered into the well. These cuttings can clog the fluid exit openings from the inside of. the bit when normal the like. The valve member normally seals the exit openings shut.The valve is operated by dropping .an operating member down through the drill string to seat on a portion of the moveable valve member, and upon application of hydraulic pressure on the operating member by pressurizing the column of mud' in the drill string, the weakened bolts break, causing the valve member'and the operating member to fall away from the relief ports. The dump'valve of the invention provides means to assure highly reliable successful operation of the valve by providing an upwardly and inwardly tapered surface between the valve member and the wall of the valve which is formed with the relief ports. A space below the'relief ports into which the movable valve member and the operating member fall is also provided to thereby position them out of the path of the rapid flow of mud and other materialsthrough the relief ports, andto create a relatively large clearance space to prevent any particle wedging anywhere in the valve once it has been operated. The tapered surface assures that the valve member will'fall downwardly and way away from the relief ports. Additionally, by providing this downwardly and outwardly tapered surface, the plane of contact between the movable valve member and the wall of'the valve body containing the ports is positioned outside of and at an angle to the normal axial flow path of mud. Thus, said plane of contact tends not to have any destructive particles which may be in the mud lodged therein. This is a material advantage for the present invention because 'of the particulate and abrasive matter always in the mud or added to it. The provision of bolts to hold the valve member in gation and consequent loosening can occur before the valve between the inside of the valve and the valve member is posi-- I tioned parallel to the direction of fluid flow through the valve,

particulate'matter in the mudcanwedge in said plane of contact, which results in leakage, and shortening of the life of the fidd tives and'other matter put'in' the mud are particulate and/or abrasive. 7

place provides'the advantage of ready renewal of the valve of the invention by simple replacement of the bolts while repositioning the valve member over the relief ports. By providing weakened portions in these bolts, a very small amount of elonoperates. v

Other advantages of the invention will be pointed out or will .become evident in the following detailed description and claims, and in the accompanying drawing also forming a part of the disclosure, in which: n

FIG. lis a longitudinal view-of avalve embodying the invention partly in cross section, partly in elevation, and partly diagrammatic;

FIG. 2 is a transverse cross-sectional view taken on line 2-2 FIG. 3 is a view similar to a portion of FIG. 1 showing the condition of the valve after it has been operated;

FIG. 4 is a partial view similar-to a portion of FIG. 1 illustrating a modified relief port structure; and

tion 24 which receives the pin or upper end 26 ofa bit or suitable conversion device 28. Bit 28 is shown diagrammatically only since the dump valve of the invention is adaptable for use with virtually any kind of bit, it being understood that suitable convertors can be added if needed. The top and

bottom portions

12 and 16, as shown, are intended for use with conventionally used drill string connections, but it will be understood that any other connection means can be used to accommodate another system.

Top and

bottom portions

12 and 16 are joined to intermediate portion 14 by welds 30 and 32respectively, it being understood that any other connection means could be used, or that the valve 10 could be fabricated in one piece.

The upper end of intermediate portion 14 is formed with an internal throat 34, which serves as a guide for the operating member, as will be explained below. From the upper end of throat 34 to the lower end of threads 18, valve 10 is formed with a series of steps 36 to bring the internal diameter of the valve down to he the diameter of throat 34. The outside surface of intermediate portion 14, at the upper end thereof, is formed with an external shoulder 38 to facilitate welding.

Extending upwardly from the upper end of threads 24 through the upper end of bottom portion 16 and the lower end of intermediate portion 14 is a cylindrical bore 40. Extending between the upper end of cylindrical bore 40 and the lower end of cylindrical throat 34, valve 10 is formed with a downwardly and outwardly sloping inclined surface 42. The wall of intermediate portion 14 at the region of sloped surface 42 is formed with three relatively large equally spaced relief ports 44. Interspaced, at equal distances, between the three ports 44 are three bolt openings 46.

Means are provided to releasably hold relief ports 44 closed against the flow of fluids through the inside of the valve. To this end, a moveable valve member 48 is provided. Referring to FIG. 3, valve member 48 is formed with a downwardly and outwardly sloped surface 50 adapted to fit snugly against sloped surface 42, and having a length less thanthe length of surface 42, for a reason that will appear below. The lower end of member 48 is clipped by a short downwardly and inwardly sloping surface 52, whereby the largest outside diameter of the member 48. i.e.. the junction of

surfaces

50 and 52 described a cross-sectional area less than the largest cross-sectional area described by surface 42, i.e., the plane ofjunction of surface 42 and bore 40.

Valve 10 is essentially cylindrical, and the various cross sections, throat, etc., described are circles or circular. This was done to facilitate manufacture, but these shapes are not to be construed as limiting since oval, prismatic, or other shapes could be substituted in places without departing from the scope of the invention. Similarly, flat areas could be provided around the exit openings to improve sealing if needed.

Surface 50 of member 48 is formed with means to receive an upper O-ring 54 and a lower O-ring 56. As shown in FIG. 1, the O-

rings

54 and 56 are positioned above and below the relief ports, to seal off these openings.

Means are provided in member 48 to form a seat for the valve operating member. To this end, the upper inner end of member 48 is formed with a downwardly and inwardly sloping tapered surface 58, the lower end of which joins the upper end ofa cylindrical throat 60. The edge 62 at the junction between sloping surface 58 and throat 60 comprises a seat for the operating member as will be described below. Starting from the lower end of throat 60, member 48 is formed with a downwardly and outwardly sloping surface 64 which extends to the bottom of member 48.

Means are provided to releasably hold the moveable member 48 in sealing relation to therelief ports 44, with surface 50 in sealing engagement with surface 42 of the valve by virtue of O-rings 54 and 56': To this end, three shear bolt as,- semblies 66 are provided. Referring to FIG. 2, each assembly 66 comprises a shank 68 pavingthreaded outer end on which is mounted a nut 70'. A ak ene'dport'ion, formed by a groove 72 or the like, is cut into hank 6 8.'As shown iri'Fl'G. I, the groove 72 is located at the rt'ace between surfa' e'e 's' 50 and 42 when the valve is assembleg 'h headmt'is on the inner end of shank 68 and a washer 76 i ated in a'suitably formed recess in surface 64 between head 74 and the moveable member 48. Washer 76 is formed of a relatively soft and relatively ductile material, such as copper, so that when the nut 70 is tightened up on its threads, head 74 and washer 76 will form a fluidtight seal on the inside of the moveable member 48 by deformation of the soft washer. Member 48i's formed with suitable bolt openings which align with openings 46 to receive bolt assemblies 66.

In use, an operating member, showiiin the form of a sphere 78, is dropped from the surface through the mud down the drill string until it meets the valve 'riie'mber. The ball is guided in its downward motion through valye 10 by cylindrical throat 34, and seats upon edge 62 to close off any further axial passage of fluids through valve 1 0} Increased pressure on thecolumn of mud above the operating member by pumping equipment at the surface causes bolt assemblies 66 to break at their weakened portions 172," whereupon the moveable member 48 with the operating i'riember 78 seated thereon fall down and away from surface 42 to thereby open the relief p rts:

The operating member 48 78is shown in the form of a sphere since this shape is simple an'd trouble free in operation. However, it is possible to have operating members of other shapes, such as an elongated torpedofformed with suitable means at its lower end to seat upon edge'62 or any other suitably formed seat at the upper end of the moveable member. The ball 78 shown may be formed 'of any suitable material which is hard enough not b to be damaged'by its travel down the drill string and has sufficient strength not to be sheared by the pressure on it when elongating and breaking the bolt assemblies 66. Suitable material for ball 78 include tungsten carbide, most ordinary grades of steel, nylon, and other materials well known to those skilled in this art.

The provision of throat 60 as one of the surfaces to form the seating edge 62 imparts the advantage of prolonged usefullife to the moveable member 48 of the invention. By providing such a throat, the edge 62 can be worn away by repeated use, and as such wear occurs, a continuous new edge will be presented, moving downwardly along throat 60, to act as a seat for the operating member. In any case, the entire moveable member 48 is easily replaced at any time while the valve is being removed if it should wear or be damaged in handling.

The provision of the groove 72 to act as weakening means provides the advantage that substantially all of the elongation of the bolt will take place in the narrow-necked portion created by the groove, and since a small amount'of material is provided at said area, it will be capable of very little elongation before breaking Thus, opening of the valve is speded and little leeway is provided for loosening of the moveable member 48 during normal operation. Such loosening would have a deliterious effect firstly because of the leakage of material through the ports 44 and secondly because of possible scoring or other wearing of the sealing surfaces 42 and 50, as well as of the O-

rings

54 and 56.

The provision of the soft washers 76 on the inside of the'bolt assemblies provides the advantage of a tight seal at this jpoint, as explained above, and additionally, provides the advantage of the ability to easily and inexpensively renew this seal by simply putting in a new washer when the dump valve 10 is renewed after each use.

Tests of a valve embodying the invention showed that after 20 hours of circulation at the rate of 450 gpm. at 5,0"O0p.s.i., the valve opened properly with a pressure of only L500 p.s.i. on the operating member.

The improvement of the dump'valve of the present invention resides, at least substantially, in the provision of thetwo downwardly and outwardly sloping surfaces'42 and 50. This I structure assures that the moveable member with the operat is totally out of the flow path of fluid down the drill string and out ports 44. The moveable member 48 falls freely because of the provision of the clipped lower corner resulting in surface 52 which assures that the largest-diameter of member 48 is less than that of bore 40. The combination of the sloping sealing surfaces and a spacebelow the valve member having a smallest diameter greater than the largest diameter of the moveable member and operating member yields the advantage that once the moveable member begins to move, it is unrestricted in further downward motion and falls freely and unrestricted away from the relief ports. In order to achieve the advantage of having the member 48 fall away, an included angle of 20 between

surfaces

42 and 50 and the vertical center line of the valve has been tested, used, and found to be satisfactory. Angles in the range of about 7 to about 25 are deemed usable.

The valve 10 is renewed by taking the valve out from between the drill string and the bit, removing the broken pieces of the bolt assemblies, the 'washers, and the operating member, repositioning the moveable member against surface 42, and sealing it in position with new bolt assemblies 66 and washers 76. The valve 10' is then ready for future service.

Referring now to FIGS. 4 and 5, there are shown modified structures for'two portions of the valve of the invention. Either one or both of these modified structures can be incorporated into valve 10, as demanded by operating conditions.

Referring to FIG. 4, there is shown a relief port 44a which is similar to relief port 44 shown in FIGS. 1 to 3, but which has been modified by the addition of a counterbore 8 0 therein extending inwardly from the outside surface of the valve and terminating at a planeinterrnediate the thickness of the wall of intermediate portion 14. Seated in counterbore 80 is a relatively thick plug 82 formed of any suitable material, such as aluminum, that will be easily consumed by the drilling process, i.e., drilled out. No additional means, other-thanthe relatively snug fit between plug 82 and counterbore 80 isused to hold the plug in position. Plug 82 serves to protect the outside surface of the moveable valve member from the hydrostatic pressure of the return fluid in the annulus between the drill string and the wellbore. Particularly in relatively deep wells, the hydrostatic head created by the column of return fluid may be sufficient to loosenthe moveable valve member, thus permitting leakage, or even premature operation of the valve. Plug 82 will be'easily. blown out of its counterbore by the press suri z ed fluid withinthe valve after it is operated. Since the plug or disc 82 is relatively thick, and is held bythe shoulder created by the the counterbore 80, it will not be pushedinwardly prior to operation of the valve.

Another problem that may beencountered under certain drilling. conditions, particularly where the well fluids are highly abrasive in nature, is that continued normal operation before the valve is used may result in slight elongation of the weakened shanks 68 of the bolt-assemblies 66-, but not necessarilyfany leakage. The same condition exit existsfrom thed time the ball seats until the instant the bolts break, and more serious erosion problemsariseduringthis time of normal elongation of the bolts prior to their breaking. Where. the well valve member until the amount of such movement becomes greater than the distance between the level of O-ring 86 in its normal position and the plane of juncture of throat 34 and sloped surface 42. This distance is made long enough to accommodate the very slight amount of movement normally experienced, yet not so long that any possible sleevelike action in throat 34 will effect normal falling of member 48.

While the invention has been described indetail above, it is to be understood that this detailed description is by way of example only, and the protection granted is to be limited only within the spirit of the invention and the scope of the following claims.

We claim:

1. A drill string dump valve comprising a valve body formed with a through passageway for the passage of fluids therethrough from an upper end to a lower end when said valve is vertically disposed, said passageway comprising a downwardly expanding section, said body being formed with an opening communicating saidsection of said passageway with the outside of said body, means to releasably seal said opening at said section against the flow of fluids therethrough.

fluids are not highly, abrasive innature the. slightlleakage resulting around O-ring 54 may not beserious,-but where the well fluids are highly abrasive, this ,leakagemay result in excessive erosion of various parts of the valveReferring to FlG. 5., the means to solve this problem comprise an elongated upper end throat portion 84 carrying an O-ring 86.which seals against throat 34 in intermediate portion 14. Thus, by providing the double seal. of O-rings 86.and 54, a slight downward movement of the moveable valve member during normal usage will not result in leakage between throat 34and the said section of said passageway comprising an upper smallest cross-sectional area and a lower largest cross-sectional area, said releasable sealing means comprising a valve member moveable within said passageway and adapted to close said opening, said valve member comprising an upper smallest cross-sectional area adapted to fit snugly within said upper smallest cross-sectional area of said section and a lower largest cross-sectional area which is a predetermined amount smaller than said lower largest cross-sectional area of said section, whereby said valve member may move freely down and away from said opening to open said opening for fluid flow, said releasable sealing means comprising an operating member adapted to pass down through the inside of the drill string to contact said moveable-valve member, said passageway comprising a throat portion extending upwardly from said upper smallest cross-sectional area thereof and adapted to guide said operating member into sealing relation with said valve member, said releasable sealing means comprising a plurality of shear bolts passing through the wall of said valve body and the wall of said valve member to hold said valve member in sealing relation with said opening, said bolts being formed with a bolt head portion positioned on the inside surface of said valve member, and means to form a fluid tight seal at the zoneof contact between said bolt head and the inside surface of said valve member. 2

2. The combination ofclaim 1, said last-mentioned sealing means comprising a washer formed of ductile mate rial adapted tobe seated in arecess formed on the inside surface of said valvemember to receive said washer,;where by tightening of said bolt will cause said head to-deform said washer-in said recess to form said fluid tight seal.

3. The combination. of claim 1,. said opening comprising plugmeans to protect said releasable sealing means against the flow of well fluids inwardly through saidopening.

4. The combination of claim 3', said plug means comprising an aluminum disc seated in a counterbore extending inwardly from the outside surface of the body of said dump valve.

5 The combination of claim 1; said releasable sealing said operating member andto locate saidmoveable valve member and said operating member below said opening after said moveable valve member has moved down away from said opening.

6. A drill string dump valve comprising a valve body formed with a through passageway for the passage of fluids therethrough from an upper end to a lower end when said valve is vertically disposed, said passageway comprising a downwardly expanding section, said body being formed with an opening communicating said section of said passageway with the outside of said body, means to releasably seal said opening at said section against the flow of fluids therethrough, said section of said passageway comprising an upper smallest cross-sectional area and a lower largest cross-sectional area, said releasable sealing means comprising a valve member moveable within said passageway and adapted to close said opening, said valve member comprising an upper smallest cross-sectional area adapted to fit snugly within said upper smallest cross-sectional area of said section and a lower largest

Claims

1. A drill string dump valve comprising a valve body formed with a through passageway for the passage of fluids therethrough from an upper end to a lower end when said valve is vertically disposed, said passageway comprising a downwardly expanding section, said body being formed with an opening communicating said section of said passageway with the outside of said body, means to releasably seal said opening at said sectioN against the flow of fluids therethrough, said section of said passageway comprising an upper smallest cross-sectional area and a lower largest cross-sectional area, said releasable sealing means comprising a valve member moveable within said passageway and adapted to close said opening, said valve member comprising an upper smallest cross-sectional area adapted to fit snugly within said upper smallest cross-sectional area of said section and a lower largest cross-sectional area which is a predetermined amount smaller than said lower largest cross-sectional area of said section, whereby said valve member may move freely down and away from said opening to open said opening for fluid flow, said releasable sealing means comprising an operating member adapted to pass down through the inside of the drill string to contact said moveable valve member, said passageway comprising a throat portion extending upwardly from said upper smallest crosssectional area thereof and adapted to guide said operating member into sealing relation with said valve member, said releasable sealing means comprising a plurality of shear bolts passing through the wall of said valve body and the wall of said valve member to hold said valve member in sealing relation with said opening, said bolts being formed with a bolt head portion positioned on the inside surface of said valve member, and means to form a fluid tight seal at the zone of contact between said bolt head and the inside surface of said valve member.

2. The combination of claim 1, said last-mentioned sealing means comprising a washer formed of ductile material adapted to be seated in a recess formed on the inside surface of said valve member to receive said washer, whereby tightening of said bolt will cause said head to deform said washer in said recess to form said fluid tight seal.

3. The combination of claim 1, said opening comprising plug means to protect said releasable sealing means against the flow of well fluids inwardly through said opening.

4. The combination of claim 3, said plug means comprising an aluminum disc seated in a counterbore extending inwardly from the outside surface of the body of said dump valve.

5. The combination of claim 1, said releasable sealing means comprising an operating member adapted to pass down through the inside of the drill string to contact said moveable valve member whereby increased pressure on the fluid in said drill string above said operating member will break said shear bolts and permit said moveable valve member with said operating member thereon to move freely downwardly, and said passageway being formed with a space below said opening sufficiently long to receive said moveable valve member and said operating member and to locate said moveable valve member and said operating member below said opening after said moveable valve member has moved down away from said opening.

6. A drill string dump valve comprising a valve body formed with a through passageway for the passage of fluids therethrough from an upper end to a lower end when said valve is vertically disposed, said passageway comprising a downwardly expanding section, said body being formed with an opening communicating said section of said passageway with the outside of said body, means to releasably seal said opening at said section against the flow of fluids therethrough, said section of said passageway comprising an upper smallest cross-sectional area and a lower largest cross-sectional area, said releasable sealing means comprising a valve member moveable within said passageway and adapted to close said opening, said valve member comprising an upper smallest cross-sectional area adapted to fit snugly within said upper smallest cross-sectional area of said section and a lower largest cross-sectional area which is a predetermined amount smaller than said lower largest cross-sectional area of said section, whereby said valve member may move freely down and away from said opening to open said opening for fluid flow, said passagewaY comprising a throat portion extending upwardly from said smallest cross-sectional area thereof, said moveable valve member comprising a throat portion extending upwardly from said upper smallest cross-sectional area thereof a predetermined distance into said throat portion of said passageway, and sealing means between said throat portion of said passageway and said throat portion of said valve member.