US2013348A - Bit head - Google Patents

Description

J. H. HOWARD ET AL BIT HEAD Sept. 3, 1935.

Filed Jan. 4, 1935 Patented Sept. 3, 1935 lTED STATES PATENT OFFICE BIT HEAD

of California Application January 4, 1933, Serial No. 650,131

4 Claims.

This invention relates to a bit head, and relates more particularly to a bit head for use on a rotary well drilling tool. It is a general object of the invention to provide a simple, prac- 5 tical and particularly eicient bit head for use on a single barrel type of core drill or core receiving well or drilling bit.

The single barrel core receiving type of well drilling bit has proved to be very rapid and efi'lcient in operation. This type of drilling bit usually embodies a tubular body or barrel and a bit head on the lower end of the barrel for making an annular cut in the earth formation. The barrel of the tool carries the circulation fluid -downwardly to the bit head, and is adapted to receive the core as the tool advances into the formation. As the core receiving type 0f well drilling bit is employed primarily as a drilling tool, it is desirable to cause the circulation fluid to erode or wash away the softer portions of the core to reduce the amount of core received in the barrel, and to prevent the soft portions of the core from choking or packing oi the barrel. In well drilling bits, it is often desirable to provide a minimum number of cutting parts of comparatively short length so that a maximum drilling pressure may be put on each unit of length of the cutting parts to increase the efficiency and drilling speed of the tool. In the single barrel core receiving type of drilling tool, the cutting parts of the bit head are arranged in an annular series and if insufficient cutting parts are provided, the rotating tool gyrates or wobbles to such an extent that the core is made Vtoo small in diameter to be properly retained in the barrel. It has been found, however, that a certain amount of gyratory motion or wobbling of the bit is desirable, as it changes or varies the relation of the cutting parts to the formation at the bottom of the well bore, and thus brings about a more rapid and elcient cutting action.

An object of the present invention is to provide a bit head for use on a single barrel core receiving type of drilling bit that handles the circulation fluid in a manner to cause it to completely erode or wash away the softer portions of the core so that the barrel receives a minimum amount of core when the tool cuts a given length of well bore.

Another object of the invention is to provide a core receiving well drill having means whereby the cuttings are rapidly washed away and are prevented from packing against the cutting parts.

Another object of the invention is to provide (Cl. Z55-72) a bit head for use on a core receiving type of well drill that materially checks or restricts the downward ow of the circulation fluid at a point where the core enters the bit head, thereby greatly increasing the velocity of the fluid so that it washes away all the softer portions of the core before the core enters the barrel and provides for an eicient washing action at the bottom of the well bore.

It is another object of the invention to provide a bit head for use on a core receiving well drill that is particularly eiective and rapid in its cutting or penetration of the earth formation.

A further object of the invention is to provide a bit head of the character mentioned that has a minimum number of cutting parts with comparatively short cutting edges whereby a maximum drilling pressure may be exerted per unit of length of the cutting parts.

A further object of the invention is to provide a bit head of the character mentioned including,V cutting parts or blades positioned and related to allow for considerable gyratory motion or wobbling of the bit whereby the relationship between the cutting parts and the formation at the bottom of the well bore is constantly changed to provide for a particularly rapid and effective cutting action.

A further object of the invention is to provide a bit head of the character mentioned having auxiliary or secondary cutting parts to limit wobbling of the bit and to protect the body or shoe of the bit head when the main or principal cutting parts have become worn to a considerable extent. The bit head provided by the present invention has auxiliary or secondary cutting parts spaced between the main cutting parts that do notY normally come into active cutting engagement with the formation, but limit the wobbling of the drill so that the bit head cuts a core sufficiently large in diameter to be dependably held and retained within the barrel and that supplement or aid the main cutting parts when they have become worn and reduced in size.

A further object of the invention is to provide a bit head of the character mentioned that is simple in construction and inexpensive of manufacture.

Further objects and features of the invention will be best and fully understood from the following detailed description of a typical form and application of the invention, throughout which description reference may be had to the accompanying drawing, in which:

' acters.

, Fig. 1 is a side elevation of a tool embodying the bit head of the present invention showing the lower end portion of the tool broken away to appear in vertical section. Fig. 2 is an enlarged vertical detailed sectional View of the bit head. Fig. 3 is a bottom elevation of the bit head vand Fig. l is a reduced sideelevation of the bit or application about to be described, but is to be n taken as including any features or modifications that may fall within the scope of the claims.`

The barrel It), of the drill illustrated in `the drawing, is an elongate tubular structure adapted to be attached to the lower end of a ,drilling string of drill pipe, or the like. A suitable connecting member II may be provided on the upper end` of the barrel I Il to facilitate the connection of the barrel with theA lower end of the drilling string. A sub or connecting member I2 is threaded on to the lower end of the barrel I0. The core catching means illustrated in the drawing s described and claimed in the co-pending application of J. C. Wright and J. B. Ragsdale entitled Well tool construction, Serial No. 650,132, filed January 4, 1933, and includes a body or sub I3 attached to the lower end of the barrel I The sub I3 has a socket I4 in its upper end receiving .a screw threaded pin on the lower end of the connecting member I2. The subr I3 is a tubular member having a central longitudinal opening I5 in direct vertical alignment with the opening of ther barrel I0. One or more blocks I6 are arranged in openings inthe walls of the sub I-3and carry core engaging dogs I1 jThe dogs I] arepivotally mounted in recesses IB in the inner sides of. the blocks I6 and project into openingsI5 to engage the core. yThe projecting ends of thev dogs I1 are rsharpened to effectively bite Y into, the core upon the drill being raised after the drilling operation. The dogs I1 are operable tov bite into theY core when the tool is raised to break the core away from the formation and act to support or retain the core in the barrel when the tool ispulled from the well bore.

Thev bit head provided by the invention includes,

generally, a body or shoe 2D, main or principal cutting parts 2I on Vtheshoe 26, and secondary cutting parts 22n on the shoe 2,,to limit the wobbling. or gyratory motion of the drill and to protect theshoe 20.

'I'he body or shoe 20 of the bit head is a tubular orannular member adapted to be mounted on the lower end of the `core receiving barrel I Il. In the; particular assembly andV combination illustrated in the drawing, the shoe 2i! is connected with the sub I3, being provided with the socket 23 in its upper end forreceiving a pin 2d, onthe lower end of the sub. The upper end 25 Lof the shoe 2I1may be iiat to seat against a downwardly facing shoulder 26 on the sub I 3. opening 2l `of. the shoe 2U is adapted to admit or pass thecore upwardly into the barrelIU. The majorJporltion of the shoeopening Z'Imay be of substantially the same diameter as the opening I5 i,n thesub` I3.

It is an important feature of thepresent in,-`

The central.

vention that the shoe 20 is formed and pro'po'rtioned to materially choke or restrict the downwardly owing circulation iiuid where the core enters the bit head. A restriction in the form of an annular inwardly projecting flange 28 provided in the lower end portion of the opening 21. 'I'he flow restricting ange 28 is preferably provided immediately adjacent the lower end of the shoe 2U in the lower end of the opening 21 so that the velocity of the' circulation fluid is greatly increased at the point where the core enters the bit head whereby the discharging fluid washes away all the soften portions of the core before the core enters the tool. The circulation uid discharging at an increased velocity and in an annular stream about the core provides for an effective washing action at the bottom of the well bore in addition to cleaning or washing away the soft portions of the core. The upper end of the flow restricting flange 28 forms an upwardly facing shoulder 29 in the opening 21 which may be inclined downwardly and inwardly as illustrated in the drawing to cause the circulation fluid to impinge against the .corep The main or principal cuttingv parts ZI are provided on the shoe 20 to make an annular cut in the earth formation. In accordance with the present invention, there is a minimum number of simple cutting parts 2l. In the typical preferred embodiment of the invention being described, there are two main cutting'parts 2l in the form of blades projecting fromthe shoe 26. The blades or main cutting parts 2l are integral with the shoe 20 and project downwardly'and outwardly from the lower end of the shoe. It

islpreferred to space the principal cutting parts` ZI equal distances apart, and in the case where.

there are` only two 4cutting parts 2I they are diametrically opposite as illustratedv in the drawing. In accordance with the broader aspects of theinvention, the mainl or principal cutting parts 2I of the bit head may have any suitable or desirable configuration. Y illustrated in the drawing, the principal cuttingY blades or parts 2I have flat substantially vertical sides 3U facing` in the direction of rotation of theV tool, and have straight lower cutting edges 3l for acting onthe formation at the bottomr of the well bore. The lower cutting edges 3| of the principal cutting blades may be radial relative to the axis of rotation of the tool and normal to the vertical axis of the tool. The outer cutting edges 32 of the principal cutting parts 2I for rearning or cuttingl the sidewalls of the well bore may be vertical. The circle X in Fig. 3 indicates the path followed bythe reaming edges 32. The upper ends 33. of the cutting parts 2l are preferably inclined downwardly and outwardly.

The cutting blades or parts' 2| are operable to cut and shape thecore. The inner cutting edges 34 of the cutting parts ZIA for cutting and a core that will havebut little clearance when it passes through the restricted lower end of the shoe opening. The circleY in Fig. 3 indicates the normal path of travel of the Ycutting edges 3d.

The main or principal cuttingfparts 2|, in beingV spaced 180 apart, allow the bit to wobble or gyrate considerably when'rot'ated. This eccentric or gyratory motion of the drill insures, the more rapidi cutting action of theblades 2|, as itprofv Videsfor a constant change in the relation be- In the particular case.

tween the blades and the formation in the well bore. It will be apparent how the principal cutting blades or parts 2| operate to scrape or cut away the formation to make an annular cut when the tool is rotated on the lower end of the drilling string in the usual manner.

The auxiliary or secondary cutting parts 22 are provided to limit the wobble or gyratory motion of the drill and to prevent excessive wearing of the shoe 2G. 'I'he cutting parts 22 are in the nature of blades projecting outwardly and downwardly from the lower end of the shoe 20; the secondary cutting blades or cutting parts 22 may be integral with the shoe 2B and may be of substantially the same shape as the principal cutting parts 2|. In accordance with the invention, the secondary cutting parts 22 are smaller than the principal cutting parts 2|, being both shorter and narrower than the principal cutting parts. The lower cutting edges 35 of the cutting parts 22 are spaced some distances above the bottom of the well bore when the principal cutting parts are new or of full size, and in active engagement with the formation.

The auxiliary or secondary cutting parts 22 are spaced between the principal cutting parts 2|. In the particular case illustrated in the drawing there are two diametrically opposite secondary cutting parts 22 each being spaced 90 from the principal cutting parts 2|. The outer edges 36 of the secondary cutting parts 22 are not as far removed from the vertical axis of the bit head as the outer edges 32 of the principal cutting parts so that they normally clear the walls of the well bore. As clearly shown in Fig. 3 the outer edges 33 of the cutting parts 22 are spaced a considerable distance inwardly from the path X of travel of the outer edges 32 of the principal cutting parts. In a like manner, the inner edges 31 of the secondary cutting parts 22 are spaced sumciently far from the axis Vof rotation of the bit head to clear the core so that they do not normally engage the core. This is clearly illustrated in Fig. 3 where the edges 31 of the secondary cutting parts are shown spaced outwardly from the path Y of travel of the edges 34 of the principal cutting parts. During the drilling operation, the principal cutting parts 2| are at all times in active engagement with the formation, while the secondary cutting parts 22 are normally out of engagement with the formation. Due to the spacing of the principal cutting parts 2 i, the bit head has a decided tendency to wobble or gyrate as it rotates, and the secondary cutting parts 22 act to limit this gyratory motion of the drill. The outer edges 36 of the cutting parts.22 may engage the formation at the side walls of the bore, While their inner edges 31 may contact with the core to limit the eccentric or gyratory motion of the drill. It is to be understood that the engagement of the edges 36 and 31 of the cutting parts 22 with the formation is not continuous, but only occurs when the motion of the drill becomes excessively irregular or eccentric. The lower edges 35 of the cutting parts 22, in being spaced considerable distances above the plane of the main cutting edges 3| do not come into active engagement with the formation until the principal cutting parts 2| have been worn away to a considerable extent. When the principal cutting blades or parts 2| become shortened through wear, and their lower cutting edges are in the same plane as the cutting edges 35, the cutting edges 35 of the secondary cutting parts may come into engagement with the formation at the bottom of the Well bore and take a portion of the drilling pressure or load. Engagement of the secondary cutting parts 22 with the formation at the bottom of the well bore decreases the rate of wear of the principal cutting blades 2| and steadies the motion of the drill. It will be apparent how the secondary cutting parts 22 prevent the shoe 20 from becoming excessively worn.

The invention provides means for continuously flushing the cutting parts 2| and 22 to prevent the cuttings from packing against them. Vertical slots 40 are provided in the flow restricting,

flange 28 to discharge the circulation fluid downwardly against the cutting blades 2| and 22. The slots 40 are located above and immediately forward of the front surfaces of the cutting parts so'that the front or active portions of the cutting parts are at all times kept free of the cuttings.

In operation, the drill involving the bit head of the present invention is attached to the lower end of an operating string of drill pipe and is rotated through the drill pipe in the usual manner. During rotation of the drill, the principal or main cutting parts 2| act on the formation to drill an annular cut and form a core. As mentioned above, the spacing of the principal cutting parts 2| is such that the tool is free to gyrate or wobble lto a considerable extent whereby the cutting parts 2| are operable to drill a comparatively large bore, the gyratory motion of the drill insuring a constantly changing relation between the cutting parts and the formation, increasing the effectiveness of the cutting parts. During normal drilling operations, the auxiliary or secondary cutting parts 22 may engage the formation at the side walls of the well bore and at the core when the motion of the drill becomes excessively irregular to limit the wobbling or gyratory motion of the drill. The secondary cutting parts 22 also operate to protect the shoe 20 of the bit head against excessive wear.

In accordance with the usual practice, circulation fluid is passed downwardly through the tool under pressure during operation of the tool to discharge from the lower end of the bit head. The provision of the flow restricting flange 28 in the opening 21 of the bit head causes the circulation uid to discharge in an annular stream about the core at a materially increased velocity, so that it is effective in washing away all the softer portions of the core as the core enters the bit head. In this manner, the softer portions of the core are positively prevented from entering the tool where they might choke or block up the barrel IU. The complete washing away of the softer portions of the core allows the tool to drill a hole of maximum length and yet receive a minimum amount of hard core. When the principal cutting parts or blades 2| have become worn to the extent that their lower edges are in the same plane as the lower edges 35 of the secondary cu-tting parts, the secondary cutting parts 22 come into engagement with the formation at the bottom of the well bore to assume a portion of the drilling load or pressure. The active engagement of the secondary cutting parts 22 with the earth formation materially lessens the rate of wear of the principal cutting parts 2|. The grooves 40 continuously discharge circulation fluid under pressure downwardly over the forward surfaces of the cut-ting parts 2| and 22 and thus prevent the cutting from accumulating on the cutting parts. It is to be noted that the bi-t head provided by the present invention is particularly simple and inexpensive in construction and effective in operation.

Having described only a typical preferred form of our invention, we do not wish to limit ourselves to the specific details set forth, bu-t wish to reserve to ourselvesV any changes or variations that may appear to those skilled in the art or fall within the scope of the following, claims.

Having described our invention, we claim:

1. A bit head for a ro-tary well drill including a'shoe having a vertical opening for receiving a core and adapted to discharge fluid downwardly, anfannular flange on the wall of said opening at its lower end whereby the fluid is discharged atan increased Velocity to wash away the soft portions of the core, two substantially diametrically opposite cutting blades projecting downwardly from the lower end of the shoe beyond all other parts of the bit head whereby the head may rock about a diametric axis as the blades engage the formation to make an annular cut and form a core which will pass through the ilange and into the opening with but slight clear- 25v have been considerably shortened through wear,

there being grooves in the said flange to discharge fluid immediately adjacent the forward faces of the blades. 2. A bit head for a core receiving rotary well drilling tool comprising a tubular shoe, two blades spaced approximately 180 apart and projecting downwardly from thelower end of the shoe beyond all other parts of the bit head so thatthe head may rock about a diametric axis when the blades engage the formationto cut an annular bore and leave a core, and other blades project-v ing from the lower end ,of the shoe. Y

3. A bit head for a core receiving rotary well drilling tool comprising a tubular shoe, two blades projecting downwardly from the shoe beyond all other parts of the' bit head and outwardly from the shoe beyond all other parts of the bit head and spaced apart circumferentially a suflicient distance to allow the head to rock about a diametric axis, and other downwardly and outwardly projecting blades on the shoe between the ,rst named blades. Y

jecting outwardly from the shoe beyond all other Y parts of the head whereby the head Vmay rock about a diametric axis as it rotates when the blades engage the formationto make an annular bore, and two blades projecting from the shoe at points spaced between the first mentioned blades to limi-t said rocking of the head and to engage the formation at the bottom of the bore upon shortening of the rst mentioned blades through wear.

Y JOHN H. HOWARD.

ALFRED C. CATLAND.

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