US2996131A

US2996131A - Lubricant packed bumper sub

Info

Publication number: US2996131A
Application number: US663576A
Authority: US
Inventors: Eugene C Greenwood
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-06-03
Filing date: 1957-06-03
Publication date: 1961-08-15
Anticipated expiration: 1978-08-15

Description

E. C. GREENWOOD LUBRICANT PACKED BUMPER SUB Aug. 15, 1961 Filed June 5, 1957 A, FIG. I

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s sheet-sheet 1 4 SI s p INVENTOR 4/ Eugene 0. Greenwood ATTORNEY 1961 E. c. GREENWOOD 2,996,131

LUBRICANT PACKED BUMPER SUB Filed June 3, 1957 3 Sheets-Sheet 2 INVENTOR Eugene (1 Greenwood ATTORNEY) Aug. 15, 1961 E. c. GREENWOOD LUBRICANT PACKED BUMPER SUB 5 Sheets-Sheet 3 Filed June 5, 1957 EUGENE Cl fiessuwoag INVENTOR.

w M w. \\E\\ /1A/ El. WW .Ew .W. v #v% J Ag g 4 4. a M M M Mi M w 4 United States Patent 9 i 2,996,131 LUBRICANT PACKED BUMPER SUB Eugene C. Greenwood, Balboa, Calif. (413 Poinsettia St., Corona del Mar, Calif.) Filed June 3, 1957, Ser. No. 663,576 24 Claims. (Cl. 175-493) This invention relates to a lubricant packed bumper sub. More particularly, the invention relates to means for protecting the splines of the bumper sub from abrasive material present in an oil well, and also relates to novel pressure-equalizing, wear-compensating, knocker head and wiper means. This application constitutes a continuation-in-part of my co-pending application, Serial No. 545,271, filed November 7, 1955, and now abandoned.

In the oil well drilling art it is highly important that the splines which associate the upper and lower components of a bumper sub be protected from the sand, dirt, and other abrasive material in the well. If the splines are not protected and lubricated they wear with great rapidity, necessitating frequent replacement of the bumper sub or components thereof. Despite this need for a bumper sub in which the splines are properly sealed and lubricated, it has not heretofore been known how to construct a lubricant packed bumper sub which will operate properly in tne drilling string during all normal operations thereof. In this connection it is pointed out that bumper subs, which are present in the drilling string during normal operation, are to be contrasted with oil well tools known as jars, which are only placed in the drilling string during abnormal conditions such as when the drill bit is stuck.

In view of the above factors characteristic of bumper subs, it is an object of the present invention to provide a bumper sub which is sealed and packed with lubricating fluid in order to prevent abrasion of the splines by material present in the well and which is so constructed that relative reciprocation of the upper and lower bumper sub components is not impeded by the lubricating fluid.

A further object is to provide a bumper sub incorporating novel pressure-equalizing means in combination with large area passage means for the lubricating fluid.

An additional object is to provide a bumper sub incorporating means for compensating for the wear on the splines or keys, in combination with means for effecting communication between opposite end portions of the bumper sub through large area spline passages.

A further object is to provide a bumper sub incorporating novel knocker head means in combination with lubricant reservoir means for replenishing the supply of lubricating fluid in the region of the splines.

An additional object is to provide an improved bumper sub which operates satisfactorily in deep wells for long periods of time without excessive wear, which prevents transmission of substantial shocks from the drill bit to portions of the drill string above the bumper sub, which maintains the drilling weight on the drill bit at a desired value, which is operable to dislodge a drill bit when the same becomes stuck, and which is used constantly during normal drilling operations so that it need not be specially inserted into the drilling string when sticking occurs.

It is a further object of the invention to provide a fluid packed bumper sub in which the tubular parts have free sliding action without the lubricant therein imparting a buffer or damping action.

It is another object of the invention to provide an improved bumper sub for drilling strings, and which is durable, non-wobbly and efficient in action.

A further object of this invention is the provision of a a bumper sub having relatively slidable tubular parts for the purpose of impact jarring, and including a self-con- Patented Aug. 15, 1961 tained closed and sealed lubricating system for the spline areas of the tubular parts. An auxiliary lubricating reservoir is provided for maintaining the lubricant in full supply in the spline area by replenishing lubricant which seeps past the packing.

A further object of this invention is the provision of an improved bumper sub, the outer tubular part of which is provided with wiper rings for maintaining the mandrel tube substantially free of mud, etc., in the area between the striking faces of the outer tube and mandrel.

An important object of this invention is the provision of a bumper sub in which the reciprocating action of the mandrel and drive sleeve is free of any fluid butler action, whereby there may be quick relative axial movement between these parts.

A further object of this invention is the provision of a bumper sub so constructed as to allow exact control of weight upon the bit.

A further object of this invention is the provision of a bumper sub which will enable the operator to have constant pipe motion in the well bore during use of the bumper sub, whereby the drill tubing above the bumper sub will not become stuck within the drill bore.

A further object of this invention is the provision of a bumper sub which, because of free sliding action of the parts, relieves strains upon the derrick, drilling lines, swivel bearings, etc.

Other objects and advantages of this invention will be apparent during the course of the following detailed description.

In the accompanying drawings, forming a part of this specification, and wherein similar reference characters designate corresponding parts throughout the several views:

FIGURE 1 is a vertical longitudinal sectional view taken through the bumper sub, showing the position of the parts for downward impact movement. In this view the chamber between the packings is shown free of lubricant to better expose details and relation of the arts.

FIGURE 2 is a side elevation of the mandrel tube of the bumper sub. It may be of one piece construction.

FIGURE 3 is a fragmentary longitudinal cross-sectional view taken through the bumper sub, with the parts in position for upstroke impact. In this view lubricant is shown in the space locations occupied by it.

FIGURES 4, 5, 6, 7 and 8 are enlarged transverse crosssectional views, taken substantially on the respective cross-section lines shown in FIGURE 1 of the drawings.

FIGURE 9 is a vertical cross-sectional view taken through the bumper sub drive sleeve. This is a detachable part for connection with the lower end of the barrel of the drilling equipment. While this view shows only the drive sleeve, it is taken in a plane through the drive sleeve represented by the line 9-9 of FIGURE 7.

FIGURE 10 is an enlarged fragmentary cross-sectional view taken through a detail of the knocker head substantially on the line 10-10 of FIGURE 3.

FIGURE 11 is a transverse cross-sectional view taken substantially on the line 11-1l of FIGURE 1.

FIGURE 12 is a longitudinal sectional view illustrating a second embodiment of the invention, incorporating pressure-equalizing means and wear-compensating means, the section being taken generally along the broken line indicated at 1212 in FIGURE 15. In this view the tool is shown closed, and the sliding packing is in a position normally assumed near the top of a well.

FIGURE 13 illustrates the embodiment of FIGURE 12 but with the mandrel in the opposite extreme position (open) relative to the barrel and drive sleeve, and illustrating the sliding packing at a position normally assumed at the bottom portion of an oil well.

FIGURE 14 is an enlarged longitudinal section of the pressure-equalizing sliding packing means employed in the embodiment of FIGURES 12-17.

FIGURE 15 is an enlarged horizontal sectional view taken on line 15-15 of FIGURE 12.

FIGURE 16 is a sectional view taken on line 16-16 of FIGURE 12, and showing the combination splineways and lubricant passages.

FIGURE 17 is a sectional view corresponding generally to FIGURE 16 but illustrating the condition of the components after the splines on the drive sleeve have been shifted to new splineways in the mandrel, thus compensating for the effects of wear between the mandrel and drive-sleeve splines.

Referring first to FIGURES lll, wherein for the purpose of illustration is shown a first embodiment of the invention, the letter A may generally designate the improved fluid packed bumper sub. Its main structural features include a barrel B, drive sleeve C, mandrel D, and knocker head E.

The barrel B is of conventional construction, including the upper portion 15 forming a tool box joint for the drilling string and having a drilling fluid passageway 16 therethrough. Its lower end is provided with an internally screw threaded tapered socket #17 to receive the upper screw threaded tapered end 17a of the drive sleeve C. The barrel B below the upper coupling is provided with a cylindrical passageway or chamber 13 of uniform diameter down to the joint socket 17.

The drive sleeve C is of substantially uniform external diameter having a tapered screw threaded end 17a for coupling to the barrel B. It is provided for its major length with a cylindrical passageway 20. Annular grooves 21 (FIGURE 9) are provided just inwardly from the lower striking face or margin 22, adapted to receive wiper rings 23, best shown in FIGURES l and 3 of the drawings, for the purpose of continuously wiping the lower part of the mandrel D during axial reciprocatory movement of the parts B and C. The wiper rings, which may comprise split O-rings (FIGURE 11), are adapted to transmit pressure therepast, and do not function as seals.

The passageway 24 at the upper end of the drive sleeve C, for a distance designated at x in FIGURES 1, 3 and 9 of the drawings, is slightly restricted and has longitudinally extending spline keys 25 therein for the distance x. These splines or keys 25 are shown in the drawings as three in number, but need not necessarily be restricted to that number. In width they form a relatively small segment of the total circumference of the passageway 24. In the illustrated sleeve C, with an external diameter of 6%, the individual widths of these keys 25 are each 1l /2 of the 360 circumference of the passageway 24. They are uniformly spaced on centers 120 apart, and therefore the passageway spaces between adjacent splines, three in number, each form an arc of 108 /2". These spaces are important, because they form area in the lubricating chamber between the mandrel and the barrel and drive sleeve along which lubricant may have free passage during reciprocatory or axial movement of the bumper sub tube parts.

It will be noted from FIGURES 1 and 3 of the drawings that the diameter of the passageway portion 24 of the drive sleeve C is less than the diameter of the passageway or chamber 18 through the lower part of the barrel B. This leaves exposed in the barrel an upper annular striking face on the top margin of the drive sleeve C. against which the knocker head E strikes during upstroke jarring action, represented by the position of the parts shown in FIGURE 3.

Referring to the mandrel or inner tubular part D, shown by itself in FIGURE 2, the same lengthwise thereof is provided with a drilling fluid passageway 40. The mandrel has an enlarged lower end 41 provided with a tool joint pin 42. Thereabove it has an externally smooth cylindrical sleeve portion 43 of less diameter than the portion 41. At the juncture of these

portions

41 and 43 there is an upwardly facing annular striking face 44 which is adapted to be engaged by the striking face 22 of the drive sleeve C on the down stroke movement of the drive sleeve. The portion 43 is annularly cut at 45 (FIGURE 2) close to the upper end thereof for receiving ring shaped packing 46, acting as a bottom seal for the lubricating chamber of the bumper sub in a manner to be subsequently described. The sleeve portion 43 has a sliding fit in the passageway 26 of drive sleeve C, as shown in FIGURE 1. Thus the wiper rings 23 will continually clean off the external surfacing of sleeve portion 43 during reciprocation of the inner and outer tubular parts forming the bumper sub.

The mandrel D above the packing 46, for the distance y, is provided with splines and splineways for slidably receiving the spline keys 25 of the drive sleeve C. At three locations externally on the mandrel D there are provided spaced pairs of

spline projections

50 and 51 defining a key way 52 therebetween for receiving a spline 25 of the drive sleeve. The widths of these individual key or

spline projections

50 and 51 may be about the same as the widths of keys 25, or slightly greater in width. Thus, when the splines 25 interfit in the splineways 52 of the mandrel there will be three spaces, each of a degree represented by are 2. The

splines

25, 50 and 51 interfit, as is shown in the cross-sectional view of FIGURE 7. These areas z provide unobstructed passageways for lubricant without damping or buffing action, during relative sliding of the drive sleeve C upon the mandrel D, in order that there will be free transfer of lubricant from one side of the closed lubrieating chamber to the other side along the spline areas.

The mandrel D, above the section y along which the splines are externally provided, is undercut to provide an annular groove 62) shown in FIGURE 2, wherein is disposed the knocker head E. As is shown in the cross-sectional view of FIGURE 6, the knocker head E is a divided or split ring composed of segments or

sections

63 and 64 adapted to seat in the groove 60 and annularly projecting therefrom. The diameter of the

sections

63 and 64 is such that when seated upon the mandrel they will have a rather close but sliding fit engagement with the wall of the chamber 13 in the barrel B.

It will be noted that when the

segments

63 and 64 are located in the groove 60 their ends will lie spaced as at 66 (FIGURE 6). These spaces 66 are lubricant passageways for replenishing the supply of lubricant to the spline areas of the inner and outer tubular parts of the bumper sub. In order to hold the knocker head segments against rotation there is provided a key 62. detachably secured by a screw 62a to one of the segments. It seats in an extension of a splineway 52 above the knocker head (see FIGURES 3 and 10). The spline keys and ways of the mandrel may be continued above the under cut or annular groove 60 if so desired.

Above the knocker head E the mandrel has an elongated diametrically reduced portion 70, the external wall of which faces the passageway 18 through the barrel B in considerably spaced relation to define an auxiliary lubricant reservoir, indicated at 71 in FIGURES l and 3. Above the reduced portion 70 the mandrel D is provided with relatively spaced annular grooves 71a and 72, adapted to receive split snap rings 73 which annularly project from the outer surface of a raised portion 74. They detachably hold a packer ring 76 which is faced on each side with packer supporting rings 77 and 78. The packer 76 embraces the wall of the chamber 18. it should be noted that the diameter of the passageway or chamber 18 is the same as the diameter of the passageway 20 of the drive sleeve wherein the packing 46 slides.

From the foregoing it will be apparent that there is a sealed lubricating chamber in the bumper sub between cant act as a buffer or a damper necessitating tensioning of the drill line in-. order to impact the striking faces.

For up stroke movement, represented by the arrangement of parts in FIGURE 3, the operator pulls the line for striking the face 30 at the top of the drive sleeve C against the projecting under surface of the knocker head E. The downward jarring action is imparted by lowering the barrel and drive sleeve for contact of the striker surface 22 of the drive sleeve against the mandrel striking surface 44.

From FIGURE 1 it will be noted that when the

surfaces

22 and 44 are in contact the spline area x assumes the position shown. Thus, there is an area in the sealed lubricating chamber below the interfitting splines Whereat a filler plug 80 is provided for adding lubricant to the lubricating chamber in the tool at time of servicing.

The axial reciprocating movement of the inner and outer tubular parts of the bumper sub is a quick action in contradistinction to locked jars, due to free lubricant passage from one side or end of the spline area to the other. The bumper sub is installed in the drill string above the drill bit, but with sections of pipe interposed between the bit and bumper sub. These pipe sections equal, together with the weight of the mandrel, the weight (drilling weight) desired to rest on the bit.

The bumper sub will allow exact control of weight on the bit because the desired drilling weight (the weight supported by the drill bit) lies below the bumper sub. When the bumper sub is touched closed (i.e. with

surfaces

22 and 44 in light, not pressure, contact) in the position shown in FIGURE 1 the only weight supported on the bit will be that of the mandrel D and other units between mandrel and bit. As the bit drills into the earth the bumper sub opens, maintaining the same weight on the bit. When the bumper sub has completely opened, this weight will be supported on the knocker head E and it will show on the Weight indicator at the top of the well, the drilling weight then being added to that of the string. The pipe can be then lowered again, closing the tool. This operation is repeated as the bore is drilled. This relieves the driller of considerable effort, it being necessary to change the position of the pipe line far less frequently than without the bumper sub of this invention. Thus, wear is saved on the brake and other equipment.

With this bumper sub the drill string can be quickly and continually raised and lowered without much effort. Keeping the pipe in such motion will result in less likelihood of it being frozen in position.

As drill bits turn on the bottom of the bore they often bounce and jump, setting up powerful vibrations throughout the entire drilling strings. This works a greater strain on the derrick, drilling lines, swivel bearings, etc. With the improved bumper sub much of such vertical vibrations will be damped out as the bumper sub opens and closes with the motion of the pipe.

It is to be understood that all parts of the bumper sub are of metal except the packing and wiper rings.

Embodiment of FIGURES 12-17 Except as specifically indicated, the embodiment of FIGURES 12-17 is the same as the embodiment described with reference to FIGURES l-l 1.

In the present embodiment, the barrel has been given the reference numeral 100, the drive sleeve 101, the mandrel 102 and the knocker head 103.

Barrel is substantially identical to the barrel 1;- described in connection with the first embodiment. The drive sieeve 101, however, is formed in two

components

106 and 107, which are removably coupled to each other by the tapered threaded socket means 108. The lower drive sleeve component 106 corresponds to the lower tubular portion of the drive sleeve C of the first embodiment, having an internal passage 20 the diameter of which is equal to the diameter of passage 18 in the barrel 100. The making of

passages

18 and 20 equal in diameter prevents, both in the present embodiment and in the previous one, the creation of an undesired piston or pumping action during relative reciprocation bet-ween the mandrel and the outer tubular component comprising the barrel and drive sleeve.

The splined or upper drive sleeve component 107 corresponds generally to the upper portion of drive sleeve C described in connection with the previous embodiment, except for a different spline construction as will be described hereinafter. Drive sleeve component 107 thus has an internal passageway 24 the diameter of which is less than the diameter of the

passages

18 and 20, forming the upper annular striking face 30 at the upper end of drive sleeve component 107. The formation of the drive sleeve in the two

components

106 and 107 permits replacement of the splined component 107 while retaining the lower component 106, as will be described subsequently.

The wiper rings 23 of the previous embodiment are not incorporated in the present one, so that the lower end of drive sleeve component 106 is not internally grooved. The lower end is, however, provided with the radial striking face 22 adapted to engage striking face 44 of the mandrel.

The mandrel 102 is diflerently splined than the mandrel of the first embodiment, as will be set forth in detail hereinafter, and is also modified so that it may be provided with the pressure equalizing sliding packing 111 which forms an important feature of the present embodiment. More particularly, the reduced upper portion 112 of mandrel 102 is formed with a cylindrical external surface of uniform diameter throughout its length. A metal packing sleeve or ring 113 (FIGURE 14) is mounted slidably around such reduced portion 112, so that it may freely slide between the upper ends of the splines on the mandrel and a snap ring 114 provided at the upper mandrel end. Leakage of lubricant or mud between the metal ring 113 and the outer surface of portion 112 is prevented by O-rings 116 provided interiorly at the up per and lower ends of the ring 113.

On its outer side, the packing ring or sleeve 113 is formed with an annular recess 117 in which suitable packing means 118 are provided. These packing means, which may correspond to packing means 119 in the lower portion of the mandrel (corresponding to packing 46 of the first embodiment), preferably comprise a plurality of elastoineric chevron elements 121 facing in opposite directions relative to a horizontal central plane. The packing means 118 bear slidably against the wall of passage 18.

The knocker head 103 is similar to the one described in connection with the first embodiment, and incorporates two split or half rings 122 and 123, each of which is slightly less than a semi-circle. These

ring elements

122 and 123 are inserted in corresponding notches at the upper end portions of the mandrel splines, so that longitudinal movement of the split rings relative to the mandrel is positively prevented. In order to prevent rotational movement of the split rings in their notches, keys 124 are integrally provided on the upper surfaces of the split rings, and rest in the spline ways between the mandrel splines.

The keys 124 hold the split rings 122 and 123 in such rotated positions that passages 126 (FIGURE 15) of equal cross-sectional area are provided between the opposed end faces of the split rings. Such passages 126 permit flow of replenishing lubricant from the reservoir 71 into the lubricating chamber between the mandrel and the outer tubular component formed by the barrel and drive sleeve.

There will next be given a detailed description of the spline or key means, and the passage means, in the mandrel and drive sleeve. The central portion of mandrel 102, below reduced portion 112 and above the larger diameter portion 43, has an outer surface 127 of uniform diameter except where splined (FIGURE 16). A plurality of splines 128 extend longitudinally of such central mandrel portion and project radially of the outer surface 127, terminating at surfaces 129 which are spaced radially inwardly from the walls of the barrel and drive

sleeve passages

18 and 20, respectively. More specifically, the outer spline surfaces 129 lie along a cylinder the diameter of which is only slightly less than the diameter of passage 24 in drive sleeve portion 107.

Drive sleeve portion 107 is provided with longitudinal splines 131 which correspond in shape to the splineways or passages between mandrel splines 128, and fit therein as illustrated in FIGURE 16. Thus, the inner surfaces of splines 131 fit slidably against the outer surface 127 of the central mandrel portion, just as the outer surfaces 129 of the mandrel splines fit slidably against the wall of passage 24 in drive sleeve portion 107 It is an important feature of the present embodiment that the number of mandrel'splines 128 is a multiple of the number of drive sleeve splines 131, and that the splines are so spaced and constructed that the channels between the mandrel splines 128 serve alternately as splineways for the drive sleeve splines and as passages for lubricant. Preferably, there are three equally spaced drive sleeve splines 131 (FIGURE 16) and six equally spaced mandrel splines 128. Also, preferably, the splines and splineways each initially occupy degrees. Thus, when the mandrel and the drive sleeve are related as illustrated in FIGURE 16, there will be three lubricant passages 132 between various pairs of mandrel splines 128. However, upon rotation of the drive sleeve sixty degrees with relation to the mandrel, lubricant passages 132 become splineways for drive sleeve splines 131, and there are three other lubricant passages 133 (FIGURE 17) between other pairs of mandrel splines 128. Accordingly, the

lubricant passages

132 and 133 serve selectively as lubricant passages and as splineways for the mandrel splines, depending upon the rotated position of the mandrel relative to the drive sleeve.

Assuming that the parts are initially assembled as illustrated in FIGURE 16, the rubbing radial surfaces of the mandrel and drive sleeve splines may wear after a substantial length of time, particularly if there should be a packing failure and consequent entrance of mud into the tool. Such wear will be much greater for the drive sleeve splines 131 than for the mandrel splines 128, due to the longer length of the latter. After a certain amount of such wear has occurred, the tool is disassembled and a new upper drive sleeve component 107 is substituted for the worn one, this being possible because of the provision of threaded socket means 108. The bumper sub is then reassembled but with the new drive sleeve splines 131 inserted, as illustrated in FIGURE 17, in the spaces or gaps between the mandrel splines which formerly served (FIG- URE 16) as the lubricant passages 132. Thus, insofar as the mating spline surfaces are concerned, a completely new tool is achieved by substituting only a relatively short and inexpensive component 107. The wear causes lubricant passages 133 to be somewhat increased in size, as illustrated in phantom lines in FIGURE 17, but this produces no harmful effect whatsoever and instead increases the freedom of lubricant passage as desired. The described wear compensating means has the effect of greatly prolonging the life of the tool without replacing the mandrel, which is very expensive as compared to the drive sleeve component 107.

The

lubricant passages

132 or 133 have a combined cross-sectional area sufiiciently large to permit free communication of fluid between the

lubricant chambers

134 and 136 which are defined between the inner and outer tube components above and below drive sleeve portion 107, respectively. These large-area passages have the effect, as previously described and as will be indicated hereinafter, of preventing a damping or dashpot action as the inner tubular member (mandrel 102) and outer tubular member (barrel and drive sleeve 101) are reciprocated or telescoped relative to each other.

When the bumper sub is shifted from its closed position illustrated in FIGURE 12, with the striker faces 2 and 44 in engagement, to the fully open position shown in FIGURE 13 and with the striker face 30 in engagement with the split rings 122 and 123, lubricant flows freely from chamber 134 to chamber 136 through the

passages

132 or 133 as the case may be. Since the lubricant flows freely through

passages

132 or 133, there is no piston action tending to force lubricant through passages 126 (FIGURE 15) into the reservoir 71 and thus against the sliding packing 111. The free communication between

chambers

134 and 136, which chambers are equal in cross-sectional area when viewed in horizontal planes, thus affords two beneficial results, the first of which is to prevent a dash-pot action as the components are reciprocated, and the second of which is to prevent undesirable inter-action with the pressure equalizing sliding packing 111. With relation to the latter beneficial result, it is to be understood that the full benefits of the sliding packing 111 are achieved because of the free communication through the

spline passages

132 and 133. For example, wear on O-rings 11s is minimized.

Proceeding next to an additional description of the func tion of the pressure equalizing sliding packing 111, the position of such packing on the upper mandrel portion 112 is independent of the position of the mandrel 102 relative to the barrel 100 and drive sleeve 101. Stated otherwise, the position of the sliding packing 111 is a function of the depth to which the bumper sub is lowered into the well, the diameters of

passages

18 and 20 and other factors which, because of the free communication through

passages

132 and 133, bear no relation to the degree of telescoping of the bumper sub components.

Before the bumper sub is inserted into the well, it is completely filled with lubricant introduced through the fill plug 80. Such filling is effected with sliding packing 111 in abutment with snap ring 114. However, because of the effects of air trapped in the lubricant chambers, leakage past the

packings

118 and 119, etc., the sliding packing 111 will be forced downwardly by the hydrostatic pressure after the bumper sub is lowered into the well. The position of the packing 111 is accordingly such that the external and internal pressures are always equal, both at the bottom of the Well when the packing 111 may be in a low position as shown in FIGURE 13, and at or near the top of the well when the packing may be in a high position such as is shown in FIGURE l2. This pressure-equalizing action has the very desirable effects of preventing stripping of seals, and preventing excessive pressure against the seals which tends to distort the packing and interfere with the free sliding of the barrel over the packing.

The position of the packing 111 is not only governed by the Well depth and by the amount of lubricant seepage, but also by the amount of wear on the walls of

passages

18 and 20. The diameters of these walls should, as pre viously stated, be equal in order that there will be no piston action as the outer and inner tubular components are telescoped. However, should these walls wear unequally, the resulting effect is largely compensated by shifting of the position of the sliding packing 111.

It is pointed out that as the parts are telescoped, sliding packing 111 moves along with the upper mandrel component 112 just as if it were secured thereto, this being because of the effects of pressure in the well and inside the tool.

The combined cross-sectional areas of the lubricant passages 132 (or 2133 after the relative positions of the mandrel and drive sleeve have been rotationally shifted) should be above a certain minimum. This minimum depends largely upon the cross-sectional area of the

lubricant chambers

134 and 136, as viewed in a horizontal plane. For constructions (such as both of the embodiments described in this application) in which the cylinder containing the outer mandrel spline surfaces (numbered 129 in FIGURE 15) is spaced approximately midway between the wall of

passage

18 or 20 and the outer surface of the central mandrel portion (numbered 127 in FIGURE 15), it has been found that the combined crosssectional area of the passages is preferably at least 25% of the combined cross-sectional areas of the mandrel and drive splines, all as viewed in a horizontal plane. Stated otherwise, the passage area should preferably add to at least 20% of the total annulus (defined between surface 127 and the wall of passage 24 in FIGURE 16). Although these minimum percentage areas are preferred, it has been found that in certain applications the passage area may be as little as 10% of the total annulus. The first embodiment, as shown in FIGURE 7, is very much above minimum. The second embodiment, as shown in FIGURE 16, is also substantially above the minimum, since three twelfths or 25% of the total annulus is occupied by the passages 132. Also, the passages 132 have a combined cross-sectional area of 33 /3% of the splines, there being three gaps or passages and mine mandrel and drive splines.

The above minimum passage area will be increased where the cross-sectional area of chambers 1134 and 136 (as viewed in a horizontal plane) is increased and may be decreased somewhat when such chamber areas are decreased. This assumes that knocker head 103, and the shoulder above packer 119, vary in size with the passages in which they slide. There should be free communication between the

chambers

134 and 136 at all times, regardless of the relative longitudinal positions of the inner and outer tubular components.

It is to be understood that the present apparatus does not require pumping of liquid longitudinally of splineways (such as number 52 in FIGURE 5) which are occupied by splines (such as number 25 in FIGURE 7). This is because the internal diameter of the surrounding tube portion, above and below the area x in FIGURES 1 and 3, is in each instance substantially larger (FIG- URE 8) than the maximum mandrel diameter at the splines. The liquid may therefore flow transversely or circumferentially over the outer curved surfaces of

splines

50 and 51, from splineways 52 into spaces z, without creating a damping or dash pot action.

Various embodiments of the present invention, in addition to what has been illustrated and described in detail, may be employed without departing from the scope of the accompanying claims.

I claim:

1. In an oil tool for use during normal drilling operations, the combination of inner and outer telescopically connected tubes movable longitudinally, means for connecting the outer tube to a drilling string, the inner tube having an end below the outer tube for connection with an object in a well bore, spline means upon said tubes to prevent relative rotation of the same and permitting their free relative longitudinal movement, said tubes being formed to provide a lubricant receiving chamber therebetween along the spline area, packer means sealing said chamber at its ends above and below the spline area, said tubes between said packer means having an unobstructed large-area passageway along the spline area for free flow of lubricant along said passageway as the tubes are axially reciprocated relative to each other, the inner tube having a striking surface facing upwardly and the lower end of the outer tube having a striking surface facing downwardly for contact with the first mentioned striking surface upon downward movement of the outer tube relative to the inner tube, a knocker head carried by the inner tube within the outer tube for longitudinal movement with the inner tube and located in and across said chamber, said knocker head having a downward-1y facing striking surface and the outer tube having an upwardly facing striking surface in position for engagement with the striking surface of the knocker head upon upward movement of the outer tube relative to the inner tube.

2. A bumper sub as described in claim 1 in which the knocker head lies appreciably below the upper packer means to provide a reservoir above the knocker head for receiving lubricant, said knocker head having sliding sur- 1 ace contact with the inner walls of the outer tube to prevent angled wobbling of the tubes, said knocker head having a passageway for flow of lubricant from said reservoir to the spline area chamber.

3. In an oil well drilling tool, the combination of a lower barrel portion having a passageway therethrough, a drive sleeve detachably connected to the lower end of said barrel portion and having a passageway therein and a first striker surface facing upwardly in the passageway of said barrel, a mandrel tube having a drilling fluid passageway therethrough, said mandrel tube being slidably disposed in the passageways of the barrel and drive sleeve, said mandrel being spaced from the inner walls of the barrel and drive sleeve to provide a lubricant chamber, upper packing means mounted upon said mandrel and operating within the passageway of the barrel substantially above said first striker surface and in sliding sealed contact with the wall of said passageway, lower packing means mounted upon the mandrel and slidably operating in sealed contact with the inner wall of the drive sleeve, said mandrel having an upwardly facing striker surface thereon and disposed exteriorly of said chamber, said drive sleeve having a second striker surface provided thereon exteriorly of said chamber below said first striker surface for impact with the striker surface of the mandrel, spline means connecting the mandrel with the drive sleeve at the upper portion of the drive sleeve to permit free reciprocation of the mandrel within the barrel and drive sleeve and to prevent rotation of the mandrel within the barrel and drive sleeve, 21 knocker head carried upon said mandrel above said first striker surface of said drive sleeve, said knocker head being located below said upper packing means, and means to permit the free non-bufling interchange of lubricant along the spline area of said mandrel and drive sleeve incident to reciprocation of the drive sleeve upon the mandrel.

4. A tool as described in claim 3 in which there is provided an auxiliary lubricant reservoir in the barrel above the knocker head, said knocker head being formed with passage means therethrough to permit the lubricant to flow into the sealed chamber at the spline connecting area of said chamber for replenishing lubricant therein.

5. A bumper sub comprising an outer tube having a passageway therealong, an inner tube having a fluid passageway therethrough, spline means connecting said tubes to permit the axial movement thereof and to prevent relative rotational movement thereof, the outer tube having an upwardly facing striker surface, the inner tube having an annular groove externally therein above said striker surface and spline means, and a split knocker head ring held in said groove against lengthwise movement and having a downwardly facing striker surface for impact with the striker surface first mentioned, said split knocker head ring having a close sliding fit upon the inner Walls of the outer tube to prevent relative 11 wobbling of said tubes, the split of said ring forming a passageway for lubricant fiow from above the knocker head to the spline area below the knocker head.

6. As an article of manufacture a mandrel for bumper subs comprising means at the lower end thereof for connection with a bit or other object, said mandrel being of elongated tubular form and at the lower end thereof above said means having an upwardly facing striking surface, said mandrel above said striking surface having an external annular packing ring receiving groove therein, the mandrel above said groove having elongated spline ways provided therealong and above said spline ways having an annular under cut knocker head receiving groove, and means externally at the upper end of the mandrel above the last mentioned groove for supporting a packer ring.

7. In a tool for imparting jarring actions to drilling strings for freeing stuck bits, drill collars and other objects within a well bore, the combination of an outer tube having a downwardly facing striker surface at its lower end and having a passageway therein provided intermediate the ends of the tube with an upwardly facing internally spaced striker face, a mandrel tube slidably disposed within the passageway of the outer tube, a knocker head carried by the mandrel above the inner striker surface of the outer tube having a downwardly facing striker surface for the upwardly facing striking surface of the outer tube, said mandrel at its lower end projecting below the outer tube and having an upwardly facing striker surface for the lower striking surface of the outer tube, packer means carried by the mandrel above the knocker head for sealing action in the passageway of the outer tube, interfitting spline means upon the outer surface of the mandrel and the inner surface of the outer tube to prevent relative rotation of the outer tube and mandrel, packer means upon the mandrel below the spline means engaging the inner walls of the passageway of the outer tube, said tool between the packer means defining a sealed chamber for receiving lubricant, said mandrel being provided with large area opened spline passages therealong at the spline connected area of the mandrel with the outer tube to permit free flow of lubricant along the spline area as an incident of relative axial reciprocation of the mandrel and outer tube.

8. A tool as described in claim 7 in which an auxiliary lubricant reservoir is provided in the outer tube between the same and a reduced portion of said mandrel, and between the knocker head and upper packer, said knoeker head having passage means therethrough for flow of lubricant from said reservoir for replenishing the supply of lubricant to the spline area chamber in said tool.

9. A bumper sub for connection in an oil well drilling string near the bottom thereof, said bumper sub being adapted to be used constantly during normal drilling operations to maintain a constant weight upon the drill bit, to absorb the shocks caused by jumping and whipping of said bit, and to produce object loosening jarring when necessary, which bumper sub comprises outer and inner tubular parts disposed in telescoped relationship, said parts having radially spaced surfaces defining between them a lubricant receiving chamber, upper and lower packer means provided between said parts at the ends of said chamber and serving to seal said chamber, longitudinal spline or key means connecting said outer and inner parts to prevent rotation thereof relative to each other while permitting free longitudinal movemrnt therebetween, said spline means being continuously engaged while said bumper sub is in the well, said spline means being disposed in said chamber for lubrication by lubricating fluid therein, stop means to limit the amount of upward and downward longitudinal movement of said outer and inner parts relative to each other, and large area passage means for effecting at all relative positions of said outer and inner parts free and unobstructed transmission of lubricating fluid between opposite end portions of said spline means, said passage means preventing said lubricating fluid from effecting a damping or dash pot action during telescoping movement of said outer and inner parts, said passage means being adapted upon assembly of said parts in different relative rotated positions to serve as splineways for spline portions of said spline means.

10. The invention as claimed in claim 9, in which said passage means comprises gaps between portions of said spline or key means, said gaps having a combined minimum cross-sectional area at least 25% as great as the cross-sectional area of said spline or key means.

11. The invention as claimed in claim 9, in which said stop means includes a knocker head mounted on said inner part in said chamber and above said spline or key means, and in which lubricant transmitting passages are provided to effect feeding of lubricant to said spline or key means from the portion of said chamber above said knocker head and below said upper packer means.

12. In an oil well tool, an outer generally tubular component, an inner generally tubular component reciprocably mounted within said outer component, the outer wall of said inner component being spaced from the inner wall of said outer component to define a lubricant chamber therebetween, means to conduct fluid through said inner component, sealing means provided between said outer and inner components at one end portion of said lubricant chamber for preventing entrance of undesired fluid into said lubricant chamber, and a pressure-equalizing sliding packing provided between said outer and inner components at the other end portion of said lubricant chamber for prevention of entrance of undesired fluid into said lubricant chamber, said sliding packing being mounted between said inner and outer components for free sliding movement relative to both of said inner and outer components, said sliding packing comprising a rigid ring mounted around said inner tubular component for free-sliding movement relative thereto, sealing means provided in said ring for engagement with said inner component and consequent prevention of leakage between said ring and said inner component, and packing means provided in said ring for engagement with said outer component and consequent prevention of leakage between said ring and said outer component.

13. In an oil well tool, an elongated outer member and an elongated inner member telescopically associated with each other, means to define first and second lubricant chambers between said outer and inner members and longitudinally spaced from each other, and spline or key means provided on said members between said first and second chambers, said spline or key means being continuously meshed for preventing rotation of said members relative to each other while permitting longitudinal movement of said members relative to each other, said spline or key means including a plurality of splines on said inner member and a plurality of splines on said outer member extending longitudinally thereof in meshed relationship, said splines being so spaced and related that the spaces or gaps between adjacent splines of one of said members serve selectively as splineways and lubricant passages for transmission of lubricant between said first and second lubricant chambers, in accordance with the rotated position at which said inner member is assembled relative to said outer member prior to introduction of the tool into the well.

14. The invention as claimed in claim 13, in which the splines on said outer and inner members are both equally spaced, and in which the number of splines on one of said members is a multiple of the number of splines on the other of said members.

15. In a bumper sub for use in oil well drilling operations, an outer tubular element comprising a barrel and a drive sleeve coupled together in longitudinal relationship, a mandrel reciprocably mounted within said outer tubular element and provided with external longitudinal spline elements equally spaced about the outer surface of said mandrel, said spline elements being relatively long, and a plurality of relatively short longitudinal splines formed internally on a portion of said drive sleeve adjacent the coupling with said barrel, said splined drive sleeve portion being removably coupled to an additional portion of said drivesleeve relatively remote from said barrel, said drive sleeve splines being equally spaced about the mandrel and being continuously meshed while the bumper sub is in the well in spaced splineways between mandrel spline elements, whereby the remaining splineways between mandrel spline elements are free of drive sleeve splines and form lubricant passages for transmission of lubricant between spaced portions of said bumper sub.

16. The invention as claimed in claim 15, in which the mandrel spline elements are six in number and are each 30 in width separated by a 30 gap, and in which the drive sleeve splines are three in number and are each 30 in width separated by a 90 gap.

17. A bumper sub for connection in an oil well drilling string near the bottom thereof, said bumper sub being adapted to be used constantly during normal drilling operations to maintain a constant weight upon the drill bit, to absorb the shocks caused by jumping and whipping of said bit, and to produce object-loosening jarring when necessary, which bumper sub comprises outer and inner tubular parts disposed in telescoped relationship, said parts having radially spaced surfaces defining between them a lubricant receiving chamber, upper and lower packer means provided between said parts at the ends of said chamber and serving to seal said chamber, at least one of said packer means being adapted to slide freely relative to both of said outer and inner parts in order to provide a pressure-equalizing action between said chamber and the drilling fluid, longitudinal spline or key means connecting said outer and inner parts to prevent rotation thereof relative to each other while permitting free longitudinal movement therebetween, said spline means being disposed in said chamber for lubrication by lubricating fluid therein, stop means to limit the amount of upward and downward longitudinal movement of said outer and inner parts relative to each other, and passage means for eifecting at all relative positions of said outer and inner parts free and unobstructed transmission of lubricating fluid between opposite end portions of said spline means, said passage means having a combined minimum cross-sectional area at least as great as the combined cross-sectional area of said spline means and passage means, said passage means preventing said lubricating fluid from elfecting a damping or dash pot action during telescoping movement of said outer and inner parts.

18. The invention as claimed in claim 17, in which said stop means includes a knocker head comprising split ring elements mounted on said inner part in said chamber and above said spline or key means, and in which said split elements are spaced apart at their ends to provide lubricant-transmitting passages effecting feeding of lubricant to said spline or key means from the portion of said chamber above said knocker head and below said upper packer means.

19. In a bumper sub for connection in an oil well drilling string near the bottom thereof, said bumper sub being adapted to be used constantly during normal drilling operations to maintain a constant weight upon the drill bit, to absorb the shocks caused by jumping and whipping of said bit, and to produce object-loosening jarring when necessary, which bumper sub comprises outer and inner tubular parts disposed in telescoped relationship, said parts having radially spaced surfaces defining between them a lubricant-receiving chamber, a pressure-equalizing sliding packing provided between said outer and inner parts at one end of said lubricant chamber and adapted to slide freely relative to both said outer and inner parts, means to seal the other end of said lubricant chamber, spline or key means provided in said lubricant chamber and longitudinally of said parts, said spline or key means permitting longitudinal or telescoping movement of said outer and inner parts relative to each other but preventing rotation of said outer and inner parts relative to each other, and large area passage means provided between the portion of said lubricant chamber on one side of said spline or key means and the portion of said lubricant chamber on the other side thereof, said passage means serving to prevent at all relative positions of said outer and inner parts operation of lubricant to eflect a damping or dash-pot action, and to prevent said lubricant from interfering with the position or pressureequalizing operation of said sliding packing,

20. The invention as claimed in claim 19, in which a knocker head is provided in said chamber and fixedly associated with said inner part for striking engagement with a strike surface on said outer part, and in which passage means are provided to effect transmission of fluid through said knocker head, said knocker head being disposed between said sliding packing and said spline or key means.

21. In a bumper sub for connection in an oil well drilling string near the bottom thereof, said bumper sub being adapted to be used constantly during normal drilling operations to maintain a constant weight upon the drill bit, to absorb the shocks caused by jumping and whipping of said bit, and to produce object-loosening jarring when necessary, which bumper sub comprises a barrel and a drive sleeve coupled together in longitudinal relationship, a mandrel mounted longitudinally within said barrel and drive sleeve and provided with a central passage for transmission therethrough of drilling fluid received from the upper end of said barrel, a pressureequalizing sliding packing provided between said mandrel and barrel at the upper end of said mandrel, said packing being freely slidable relative to both said mandrel and barrel, packer means provided at the lower end of said mandrel for sliding sealing engagement with the interior wall of said drive sleeve at the lower portion of said drive sleeve, said sliding packing and said packer means serving to seal a lubricant chamber defined between said mandrel and said barrel and drive sleeve, relatively long longitudinal splines provided externally on said mandrel in said lubricant chamber, relatively short internal splines provided at the upper portion of said drive sleeve and meshing with said mandrel splines to prevent relative rotation between said mandrel and drive sleeve while permitting telescoping movements therebetween, large area passage means provided between the splines of at least one of said telescoped elements and serving to effect transmission of lubricant between opposite end portions of said lubricant chamber, said passages being sufliciently large to permit free lubricant movement therethrough at all relative longitudinal positions of said mandrel relative to said barrel and drive sleeve for prevention of dash-pot action therebetween, a knocker head fixedly mounted on said mandrel beneath said sliding packing and adapted to engage a strike surface at the upper end of said drive sleeve upon shifting of said mandrel to a relatively open position relative to said barrel and drive sleeve, strike surface means provided between the lower portions of said drive sleeve and said mandrel for engagement upon shifting of Said mandrel to a relatively closed position relative to said drive sleeve, and passage means provided through said knocker head.

22. The invention as claimed in claim 21, in which the cross-sectional area of the portion of said lubricant chamber below said knocker head and above said drive sleeve splines is constant and is equal to the cross-sectional area of the portion of said lubricant chamber below said drive sleeve splines, the latter area also being constant, such cross-sectional areas being relatively small in comparison to the cross-sectional area of the portion of said lubricant chamber between said sliding packing and said knocker head.

23. The invention as claimed in claim 21, in which said drive sleeve splines are equally spaced, and said mandrel splines are also equally spaced and are twice as numerous as said drive sleeve splines, the gaps between said mandrel splines being equal in size to said drive sleeve splines and serving selectively as splineways for said drive sleeve splines and as lubricant passages.

24. The invention as claimed in claim 21, in which the lower portion of said drive sleeve is removably secured to the upper splined portion thereof, and in Which the inner diameter of said lower portion is equal to the inner diameter of said barrel.

References Cited in the file of this patent UNITED STATES PATENTS 1,798,480 McCullough Mar. 31, 1931 1,801,673 Knox Apr. 21, 1931 1,900,932 Hollestelle Mar. 14, 1933 2,096,135 Raymond Oct. 19, 1937 2,585,995 Brown Feb. 19, 1952 2,645,459 Sutliff July 14, 1953 2,721,056 Storm Oct. 18, 1955 2,818,232 Osmun Dec. 31, 1957 2,828,944 Udry Apr. 1, 1958 2,891,77 Segelhorst June 23, 1959