US2585995A - Drilling joint - Google Patents

Description

Feb. 19, 1952 c. c. BROWN 2,585,995

DRILLING JOINT Filed March 2l, 1947 uff- I 7K www vala

INVEN R.

FIG.2 'BY @W ATTORNEYS Patented F eb. 19, v1952 UNITED STATES PATENT OFFICE DRILLING .OIN'

Cicero C. Brown, Houston, Tex.

Application March 21, 1947, Serial No. 736,359

1945. The device of this invention provides an improved means for controlling the weight applied to the drill bit, localizes the neutral point in the drill steam, and prolongs the life of the drill stem by absorbing or damping out Vibrations and other shocks imparted to the drill stem during operations.

Heretofore in devices of this character the relatively movable splines or other. non-circular connections between the telescoping members have been exposed to the abrasive matter of the Well drilling iluid. This abrasive matter materially reduces the life of the device and often times interferes with its intended operation. The use of rubber or rubber like material in the splined inner connection has been recommended and has certain advantages in that the drilling iluid serves as a lubricant and the abrasive matter does not have the same wearing effect upon the resilient material of this type spline. However, this type connection has not proved entirely satisfactory for all purposes due to `the inherent weakness of this material in the transmission of the heavy loads often encountered in drilling -U deep well bores.

An object of this invention is toprovide av drill stem telescope joint in which the working parts of the telescope members are housed in a sea-led chamber and thus protected from abrasive materials. l 4

Another object is to provide a drill stem telescope joint in which the relatively movable, torque transmitting parts between the telescope members are housed in a sealed chamber filled With a lubricant.

A further object is to provide a drill stem telescope joint in which the torque transmitting relatively movable parts between the telescoping members are housed in asealed chamberwhich may be filled with hydraulic material whereby likelihood of collapse ofv the outer member is re.- duced.

Still another object is to provide a tool of the character described wherein the relatively slidable torque transmitting parts may be constructed of rigidl wear-resisting material and shielded from abrasive foreign matter.

Other and further objects will appear from the following description.

4 Claims. (Cl. Z55-'28) In the accompanying drawings whiph constitute a part of the instant specification and are to be read in conjunction therewith, and wherein like reference numerals designate like parts of the various views:

Fig. 1 is a schematic sectional view of' a well bore showing in elevation a drill stem and tools equipped with a device embodying this invention; Y Fig. 2 is alvertical sectional view of the upper portion of theV device shown in Fig. l;

Fig. 3 is a vertical sectional view of the lower portion of the device shown in Fig. l; and

Fig.. 4 is a view taken along the line 4-4 in Fig. 3 in the direction of the arrows.

Referring to the drawings, more particularly Fig. 1, the well bore is shown schematically at I0. Joints Il ofthe drill stem are suspended fromthe surface in a manner well known to those skilled in, the art and have interposed therein the device of this invention. The drill .bit I2 is attached by a suitable drill collar I3 to the lower end of the telescope joint. In actual operation a suitable number of drill collars will be used to give the desired weight at the bottom of the hole. A selected drilling weight can by this manner be located below the telescope joint, thus maintaining a uniform load upon the bit.

With regard tol the drill stem telescope joint, it may be considered that the device comprises in general two telescoping members. The outer ofthe members includes a coupling sleeve Irl which has threaded connection with the lower most drill stem joint Il. Sleeve I4 has an enlargecl boreV [4a which provides a recess for housing the lip'typepacking ring I 5. The packing ring may be made of any suitable resilient material such as rubber, neoprene or other synthetics.

At itsy lower end coupling sleeve I4 threadedly receives a tubular sleeve I5. The upper end of tube I6 is threadedly connected to a packing carrier I1 which carries seal member I5. The internal bore-Ia of the tubular sleeve provides a smooth cylindrical surface of uniform diameter to cooperate with sealing means carried bythe inner telescoping member as willbe hereinafter more fully described. A bore ISb is provided in sleeve I6 leading into the upper end of the interior of sleeve I6 to maintain the proper pressure differential' across seal member I5.

The lower end of sleeve I6 is threadedly connected to spline carrier I8. The spline carrier is provided with a valved opening I8a. This valved opening provides a means for forcing a hydraulic or lubricating material into the space between l the telescoping members with the tool assembled.

the component parts of the outer tubular member. By using these buttress type threads the parts of the outer member may be constructed of somewhat narrower gauge. It is of course understood that in drilling operations the maximum outside diameter of the joints of a drill stem must be kept low in the interest of economy.

The inner telescope member comprises the coupling member 2|), mandrel 2| and sealing or flow tube 22. aThe coupling provides an attachnient for the lower end of the device with the drill collar I3. In addition the shoulder 20a of the coupling engages the lower end of sleeve I9 providing a stop for telescoping movement of the inner and outer members.

The mandrel 2| intermediate its ends is provided with elongated external splines 2|a. These splines mate with splines I8b of the outer member. Preferably the splines are the buttress type. The buttress type splines are of V-shape but have one side inclined with respect to a radius through its apex and the other side extending along a radius. This arrangement provides an enlarged driving surface between the spline members. In addition, the arrangement provides a shear area for each spline which is equivalent to the entire base of the spline, and the total shear area for all of the splines on either element is equal to the length of these splines times the entire circumference of the respective elements at the bases of the splines. Furthermore, the driving surfaces are kept at a sufficiently great angle with respect to the direction of application of driving force on each spline to reduce the'likelihood of their sticking. This angle also facilitates a relatively easy sliding movement between the surfaces even while under torque load. Throughout this specication this type spline will be referred to as buttress type splines.

In order to provide a sealed chamber for the working parts or splined connection between the members, seals are provided between the telescope members adjacent the ends of the elongated splines 2Ia. At the lower end the mandrel has a portion 2lb having substantially the same outside diameter as the inside diameter of tubular sleeve I9. Sliding seal means are provided between the portion 2lb and sleeve I9. Preferably these seals are of the O-ring groove assembly type. A groove is provided in the outer periphery of portion 2lb. O-ring 23 ts loosely within the groove and normally has sufficient outside diameter to frictionally engage the internal wall of sleeve I9. In as much as portion 2lb is enlarged, the groove does not weaken the mandrel.

A similar seal is provided at the top end of the elongated splines 2|. To facilitate assembly of the tool this is accomplished by means of a seal carrier ring 24 threaded to the upper end of mandrel 2|. Again the seal is preferably formed by use of an O-ring groove assembly. A groove is provided in the outer periphery of ring 24 and loosely receives O-ring 25. This O-ring normally has sulcient outside diameter to frictionally engage the internal wall of tubular sleeve I6. Preferably ring 24 has a close tolerance with the inner surface of sleeve I6.

It is important that with the telescoping members in their extreme telescoped position the lower end of sleeve I9 abuts shoulder 20a of coupling 20. Thus, in this position, the splines of the splined connection are protected against ldistortion from a jar, as the splines themselves do not form the means of stopping or limiting telescoping movement of the members. In this respect, the splines are likewise protected from distortion by shoulders 24a of the seal carrier and shoulder |8c of the spline carrier. These shoulders engage and serve as stops limiting extension of the telescoping members.

The sealing or flow tube 22 is threaded to mandrel 2| and extends upwardly into the lower drill stem joint II. The length of tube 22 must be sufficient to provide a. sealing surface cooperable with lip seal I5 when the inner and outer telescoping members are in their extreme extended position. This arrangement is such that an auxiliary seal is provided against flow of drilling fluid between the two telescoping members. Nevertheless, when the members are in their extended position and are forced to their telescope position fluid within the space formed between flow tube 22 and the outer member may readily flow past the lip type seal member I5 when the pressure beneath the seal is greater than that above the seal. The tube provides a flow passage for drilling fluid from the lowermost joint I I to the mandrel.

While the sealing assemblies, including O- rings 23 and 25, seal off the chamber which houses the splined connection protecting the relative sliding parts from abrasive material this protection may be made more positive by filling this chamber with a light lubricating oil or the like. Valved opening I8a provides a means for accomplishing this. Preferably this hydraulic material is forced into the chamber under pressure which will be substantially that encountered in drilling operations. This material serves a four fold purpose. It reduces the likelihood of abrasive or other foreign matter seeping past the seal assemblies, protects sleeves |6 and I9 from excessive hydrostatic pressures, lubricates the splined connection and serves as a dash-pot to absorb or dampen vibrations and other shocks to which the drill stem is subjected in drilling operations.

Preferably, when the lubricant bath is provided for the splines, one of the splines 2 Ia, is truncated throughout most of its length as shown at 26 in Figs. 2 and 4. By this expedient the dashpot effect, due to restricted flow of the lubricant past the spline engagement is reduced throughout most of the stroke or relative movement of the members whereby they move relatively freely and at the same time there is provided a dampening of excessive shocks, Vibrations and the like. As the entire length of the spline is not ground off relative longitudinal movement of the splines is much slower when the inner and outer members are completely telescoped.

It is believed that the operation of this invention is obvious from the foregoing description. 'I'he tool is interposed in a pipe string usually between the lower-most drill stem joint and the upper-most drill collar. However, it is often desirable to interpose drill collars above the telescope joint as this sometimes facilitates drilling of a straight hole as will be understood by those skilled in the art. Tools are lowered into the well bore until bit l2 engages the bottom of the bore. Sufficient Weight is placed upon the drill stem to telescope the inner and outer members of the telescope joint, rotary slips are set and the tools rotated.

As the bit bores into the formations the drill stem and outer member of the telescope joint remain at a substantially constant level. However, the inner member of the telescope joint moves downwardly reecting the progress made by the drill bit. Thus, the weight on the bit may be maintained at a constant. Also, the neutral point within the drill string, namely that point at which there is neither compressive nor tensile stress, is localized within the joint. Thus, the tendency to disengage the coupling at or adjacent the neutral point may be overcome by use of right hand threads or the like.

It is obvious that the iiow of lubricant past the spline engagement when the telescoping members change their relative axial positions is greatly restricted due to the close tolerance in the splined fitting. Thus, a dash-pot eifect is obtained which serves to absorb or dampen vibrations and other shocks or jars occasioned by the action of the drill bit upon the formation, whipping of the drill stem and the like. In as much as the lubricant is forced into this space under pressure the space is completely lleol and excessive hydrostatic pressures to which the outer member may be subjected are transposed to the inner member which is of heavier construction and is better able to withstand this pressure. In addition the lubricant increases the life of the tool both in its action as a lubricant and because of the shielding of the device from gritty or abrasive substances.

It will be seen that the objects of this invention have been accomplished. There has been provided a drill stem telescope joint capable of supplying a rigid connection for the transmission of torque which simultaneously permits extension of the joint as the drilling progresses. The arrangement is such that the working parts operate in a sealed chamber and are thus protected from abrasive material. 'I'he construction provides for an oil bath for the working parts of the tool, thus prolonging its life.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and sub-combinations are of utility and may be em- Y ployed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having described my invention, I claim:

1. A drill stem telescope joint including an outer tubular member, an inner tubular member adapted to telescope the outer member, a spline connection between the members, a sealing means at each end of the spline connection whereby said connection is protected from abrasive matter, said members telescoping each other beyond the spline connection with the inner member being of a reduced diameter beyond said connection, and

an auxiliary lip-type packing ring carried by the outer member and havingits bore engaging the exterior surface of the reduced portion of the inner member, the exterior of the packing ring being exposed to the pressure of the iiuid within the drill stem to which the joint is connected whereby said pressure fluid maintains the packing ring in sealing engagement with the inner member, the outer member below 'ti packing ring having means for establishing c 1.nnunication between the area externally o1' said outer member and the bore of the packing ring, said ring allowing a by-pass of pressure in the event the pressure acting against its bore adjacent the inner member exceeds the pressure which is acting on its external surface.

2. A drill stem telescope joint including, an outer tubular member, an inner tubular member adapted to telescope the outer member, the upper end of the outer member projecting beyond the upper end of said inner member, a spiine connection between the members, a sealing means at each end of the spline connection between said members whereby said connection is protected from abrasive matter, a reduced diameter flow tube extending upwardly from the inner member and projecting axially through the outer member above the spline connection between the member, an annular packing element carried by the outer member and spaced above the upper end of the inner member, said element having an upwardly directed sealing lip engageable with the exterior surface of the flow tube for sealing ofi in a downward direction between the tube and the outer member to protect the sealing means at the ends of the spiine connection, the exterior of said packing element being exposed to pressure fluid circulated downwardly into the outer member whereby such fluid maintains the packing element in sealing position, and means for establishing communication between the area exteriorly of the outer member and the annular space between the interior ci the outer member and ow tube below the annular packing element, whereby pressure from exteriorly of the outer member may by-pass up- Wardly around the flow tube and past the annular packing element in the event that this pressure exceeds the fluid pressure acting on the ex terior of the packing element.

3. A drill stem joint as set forth in claim 2, wherein the splines of the spline connection between the members are buttress splines.

4. A drill stem joint as set forth in claim 2, together with stop means separate from the splines of the spline connection for limiting the relative movement in both directions of the inner and outer members with respect to each other.

CICERO C. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,737,508 Mercer Nov. 26, 1929 1,801,673 Knox Apr. 21, 1931 1,844,257 Lincoln Feb. 9, 1932 1,900,932 Hollestelle Mar. 14, 1933 2,172,481 Osmun Sept. 12, 1939 2,240,519 Reed May 6, 1941 2,302,856 Hamon Nov. 24, 1942 2,422,223 Church June 17, 1947

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