US2544993A

US2544993A - Drill bit

Info

Publication number: US2544993A
Application number: US748927A
Authority: US
Inventors: Jackson John Gordon
Original assignee: Eastman Oil Well Survey Co
Current assignee: Eastman Oil Well Survey Co
Priority date: 1947-05-19
Filing date: 1947-05-19
Publication date: 1951-03-13
Anticipated expiration: 1968-03-13

Description

March 13, 1951 J. G. JACKSON DRILL BIT 2 Sheets-Sheet 1 Filed May 19, 1947 awue/wroc John Gordon Jackson March 13, 1951 J. G. JACKSON DRILL BIT 2 Sheets-Sheet 2 Filed May 19, 1947 k C a J n o d r o Patented Mar. 13, 1951 mam. err

John Gordon Jackson, Denver, 0010., assignor to Eastman Oil Well Survey Company, Denver, 0010., a corporation of Delaware Application May 19, 1947, Serial No. 748,927

Claims.

This invention relates to new and useful improvements in drill bits.

The invention relates particularly to that type of drill bit, generally known as a trigger bit.

As is well known, trigger bits are employed in oil well drilling and are ordinarily constructed of a bit body having an axial bore and provided with exterior cutting blades which perform the drilling operation. It is usual practice to provide some means for normally closing the axial bore so as to prevent the entrance of a core up= wardly therein. When it is desired to take a core, suitable core taking equipment is lowered through the bore with the core barrel of such equipment extending outwardly in advance of the bit. Trigger bits also have other uses such as permitting a well survey instrument to extend outwardly through the axial bore thereof, where-- by information as to deviation and direction of deviation may be obtained while the bit and drill stem remain in the well bore.

1 through the bore of the bit when the core-break.-

It is one object of the present invention to provide an. improved trigger bit which is constructed so that during the normal drilling op eration, the circulated drilling fluid is utilized to the maximum extent, whereby efiicientdrilling. is assured; said bit also having means which will permit core taking or other apparatus to extend therethrough and in advance thereof.

It is another object of the invention to provide an improved drilling bit of the trigger type which is provided with an axial bore and which has improved means for normally substantially closing said bore to prevent the admission of a core during normal drilling operations.

An important object of the invention is to provide an improved trigger bit having the usual exterior cutting blades and also having pivoted core-breaking blades which normally swing inwardly to substantially close the axial bore extending through the bit; the pivoted core-breaking blades being readily movable to an outer position whereby a well survey instrument or other apparatus may be moved downwardly through the bore to extend in advance of said bit.

Another object of the invention is to provide an improved trigger bit, of the character described, wherein the pivoted core-breaking blades are formed with deflector elements which, when the blades are in their inward or closed position,

substantially close the axial bore through the bit to restrict the flow of the drilling fluid, whereby said fluid is caused to be directed onto the main cutting blades under a relatively high velocity;- said deflector elements being so constructed that ing blades are in their outer or extended position.

A still further object of the invention is to provide a trigger bit, of the character described, wherein the deflector elements which substan tially close the bore of said bit are disposed in such a manner with respect to the main cutting blades of the bit that any fluid which escapes from the lower end of said bore, past said ele-- ments is directed into immediate contact with said cutting blades, whereby eflicient lubrication of the bit is assured The construction designed to carry out the invention will be hereinafter described together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawing, wherein an example of th invention is shown, and wherein:

Figure 1 is an elevation of a drilling bit constructed in accordance with the invention,

Figure 2 is an elevation of the bit taken at a right angle to the position shown in Figure 1,.

Figure 3' is a transverse, vertical, sectional view taken on the line 3-3 of Figure 1.,

Figure 4 is a view similar to Figure 3- illustrating the core-breaking blades swung to their outward position,

Figure 5 is a transverse, vertical, sectional view taken on the line 55 of Figure 2,

Figure 6 is a horizontal, cross-sectional View taken on the line 66 of. Figure 1, and

Figure '7 is an isometric view of the corebreaking blades illustrating the deflector elements associated therewith.

In the drawings, the numeral Iii designates a bit body which is generally cylindrical in crosssection and which. is gradually reduced toward its lower end. The upper end of the body has an internally threaded box. H made integral therewith and. this box is of standard. construction for receiving the lower end of the drill pipe or sub (not shown). Diametrically opposed cut ting blades 12 are formed integral with the body it) and extend outwardly in a radial direction. Each cutting blade is provided with a sharpened lower cutting edge It and the forward or cutting surface i2a of each blade extends in substantially the same longitudinal plane as the axis of the body iii. The rear portion of each blade is, suitably reinforced by an enlargement [2b which is integral with the bit body. When the bit is rotated, the main cutting blades l2 perform the digging operation in the usual manner.

Extending downwardly from the threaded box H is an axial bore it which passes entirely through the bit body and has its lower end open, whereby drilling fluid circulated downwardly may be ejected from the lower end of said bore. Inclined upper ports l5 may extend from the upper end of the bore It to a point adjacent the upper end of the forward surface of each main cutting blade I2 but if desired, these ports may be omitted. Similar lubricating passages it which may be formed by cutting or milling a recess in the wall of the body adjacent the lower end of the bore also establish communication between the bore and the forward face l2a of the blades. With the provision of the ports, 25, circulation of fluid downwardly through the bore it causes some of the fluid to be ejected outwardly through said ports and also through the passages 16 onto the faces 12a of the cutting blades, whereby said blades are lubricated and also whereby the cuttings which are removed from the formation by the blades are circulated to the surface.

Diametrically opposed longitudinal ribs H are formed integral with the bit body (0 and these ribs are disposed at substantially a right angle to the diametrically opposite main cutting blades Ill. The lower end of each rib is bifurcated to form depending ears l8 between which is pivoted a core-breaking blade l9. As is clearly illustrated in Figure 7, each core-breaking blade includes the blade portion 23 which has an upstanding extension or lug 2i preferably made integral therewith. The lug has a transverse opening 22 which aligns with complementary openings 23 in the ears l8 and a pivot pin 24 mounts each blade on the bit. When swung inwardly, the blade portion 2i} of each core-breaking blade overlies the open lower end of the bore M of the bit body. Because the lug 2| extends upwardly above the blade portion of each corebreaking blade it, a shoulder or flat surface 25 is formed by the top of said blade portion and when the blades are swung to their inward position, the shoulders or surfaces 25 are located immediately below the open lower end of the bore M.

For restricting the area of the bore M so as to setup a back pressure and cause the drilling fluid to be ejected forcibly through the inclined ports :5 and passages I6 onto the forward surfaces of the main cutting blades and also for deflecting anyfluid escaping from the lower end of the bore onto said blades, each core-breaking blade isformed with a deflector element or plate 26. Each element or plate is secured in any suitable manner to the shoulder or surface 25 of its blade is and as is clearly illustrated in Figure l, the plates 26 are inclined in opposite directions from a horizontal plane when the corebreaking blades 19 are in their inward position. Thus, when the blades is are swung inwardly beneath the open end of the bore 14 of the bit, the deflector elements or plates are disposed immediately below said open end. These plates are of such area as to substantially close this lower end of the bore and, therefore, when in an inward position any circulation of fluid downwardly through the bore is restricted by said deflector elements; this restriction of circulation sets up a back pressure within the bore 14 which causes the fluid to be forcibly ejected under a relatively high velocity through the inclined ports l5 and passages l6 onto the forward or cutting faces [2a of the main cutting blades. Because the deflector plates or elements do not completely close the bore, some fluid will escape from the lower end thereof and this escaping fluid is properly directed against the cutting blades by the inclination of the deflecting elements. It is noted that the inclination of one of the deflecting plates 26 is such that a portion of the circulating fluid escaping from the bore M is directed against one of the main cutting blades l2, while the disposition of the other blade directs the remainder of said fluid against the second cutting blade. Thus, it becomes obvious that the circulating fluid is forced into direct contact with the cutting blades 12 through the ports 55, passages 16 and by means of the inclined deflector blades. In this manner, ample lubrication of the main cutting blades i2 is assured and also the washing-up of the cuttings removed by the main blades i2 is carried out.

In the operation of the bit, the main blades 52 perform the drilling operation and the pivoted smaller blades 19 merely function to break the core which would normally move upwardly within the bore 1 3. Therefore, under normal drilling, the core-breaking blades i9 are in substantially the position shown in Figure 3, that is they are moved inwardly. Any tendency of the blades to move to an outward position will be restricted by the engagement of the lower end of said blades with the formation and in such position, the deflector plates 25 substantially close the lower end of the bore. So long as the fluid circulated through the bore is restricted, assurance that the fluid will be directed outwardly through the ports IS and passages l6 under a relatively high velocity is had. Of course, the disposition of the deflector plates is important because it definitely utilizes the fluid which does escape from the lower end of the bore for lubricating and washing the surfaces of the main cutting blades.

When it is desired to run a survey instrument or other apparatus through the bore M of the bit it is only necessary to lift said bit off bottom and then run said apparatus through said bore. The apparatus upon striking the deflector plates 26 will swing the core-breaking blades [9 outwardly to the position shown in Figure 4. In this position, the blades are moved completely out of alignment with the bore 14 to thereby permit the well survey instrument or other apparatus to extend outwardly in advance of the bit.

From the foregoing it will be seen that a very simple and efficient trigger type bit is provided. The core-breaking blades are normally in an inward position during the drilling operation and in such position, the deflector plates 28 function to break the core and also to substantially close the bore [4 to restrict-the circulation of fluid therethrough. As has been stated, this restriction of the circulating fluid assures that the major portion of the fluid will be forced outwardly under a relatively high velocity through the ports l5 and passages I6. The remaining fluid which escapes past the deflector plates 26 is, because of the inclination or disposition of said plates, forced directly into contact with the cutting faces I211 of the cutting blades 12. With this arrangement all of the fluid which is circulated is utilized to the fullest extent in lubricating and washing the bit blades, whereby balling up of the bit is definitely prevented. The deflector plates are so arranged that they do not interfere with the opening of the core-breaking blades to permit the running of a well survey instrument or other apparatus through said bit.

As has been noted, the inclined circulation ports I5 may be omitted without interfering with efficient operation of the bit; in such instance,

the circulation downwardly through the bore 14 will be forced outwardly through passages I6 and the spaces around the deflector elements and although the volume of fluid in, this case is not asmuch as when the ports l5 are provided, yet said volumeis sufficient to properly lubricate the blades and to wash the" cuttings to the'surface.

The foregoing description of the invention is explanatory thereof and various changes inthe size, shape and materials, as well as in the details of the illustrated construction maybe made, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A drill bit including, a body having an axial bore extending therethrough, main cutting blades on the exterior of said body, circulating passages extending from thebore of the body to the blades,

whereby fluid circulated downwardly through the bore may flow through said passages and onto the blades to lubricate and wash the same, corebreaking blades pivotally mounted on the lower portion of the body and arranged to swing inwardly beneath the open lower end of the bore, and means on said core-breaking blades for establishing a wall area across the open end of the bore substantially equal to the cross sectional area of the bore and thereby restrict the flow of fluid through the bore when said blades are in their inner positions, whereby a back pressure is built up within the bore and fluid is forcibly ejected under relatively high velocity through the circulating passages onto the main cutting blades to assure eflicient lubrication and washing thereof.

2. A drill bit including, a body having an axial I bore extending therethrough, main cutting blades on the exterior of said body, circulating passages extending from the bore of the body above its lower open end to the blades, whereby fluid circulated downwardly through the bore may flow through said passages and onto the blades to lubricate and wash the same, core-breaking blades pivotally mounted on the lower portion of the body and arranged to swing inwardly beneath the open lower end of the bore, and means on said core-breaking blades for forming a wall of an area substantially that of the bore across the lower open end of the bore for restricting the flow of fluid through the bore when said blades are in their inner positions, whereby a back pressure is built up within the bore and fluid is forcibly ejected under relatively high velocity through the circulating passages onto the main cutting blades to assure efiicient lubrication and washing thereof, said last-named means also functioning to deflect the fluid which is discharged from the lower end of the bore outwardly at a sharp angle to the bore axis and against the main cutting blades.

3. A drill bit including, a body having an axial bore extending therethrough, main cutting blades on the exterior of said body, circulating passages extending from the bore of the body to the blades, whereby fluid circulated downwardly through the bore may flow through said passages and onto the blades to lubricate and wash the same, core-breaking blades pivotally mounted on the lower portion of the body and arranged to swing inwardly beneath the openlower end of the bore, and a deflector element in the form of a plate mounted on each core-breaking blade, said elements being located tobecome positioned to form a wall below and extending substantially across the open lower end of the bore of the bit body when the core-breaking blades are in their inner position, whereby saidelements restrict flow through said bore and assure the ejection of a circulating fluid outwardly through thecirculating passage under a relatively high velocity to assure eflici'ent washing and lubrication of the maincutting blades.

4. A drill bit including, a body having an axial bore extending therethrough, main cutting blades on the exterior of said body, circulating passages extending fromthe bore of the body to the blades, whereby fluid circulated downwardly through the bore may flow through said passages and onto the blades to lubricate and wash the same, core-breaking blades pivotally mounted on the lower portion of the body and arranged to swing inwardly beneath the open lower end of the bore, and a deflector element mounted on each core-breaking blade, said elements being located below and extending substantially across the area the open lower end of the bore of the bit body when the core-breaking blades are in their inner position, whereby said elements restrict flow through said bore and assure the ejection of a circulating fluid outwardly through the circulating passage under a relatively high velocity to assure efllcient washing and lubrication of the main cutting blades, said elements being disposed at an angle from a horizontal plane with the particular disposition being such that the fluid discharged from the open lower end ,of the bore is directed outwardly at a sharp angle against the faces of the main cutting blades.

5. A drill bit as set forth in claim 1, wherein the means for restricting the flow through the bore comprises flat deflector plates with one plate mounted on each core-breaking blade.

6. A drill bit as set forth in claim 4, wherein the deflector elements comprise flat plates and also wherein one of the plates is inclined in an opposite direction from a horizontal plane to the inclination of the other plates, whereby each plate deflects a portion of the circulating fluid discharging from the lower end of the bore onto one of the main cutting blades.

7. The combination with a drill bit having a bit body provided with exterior main cutting blades with radially extending faces projectil'lg upwardly alongside the bit body and having an axial bore with fluid circulating passages extending from the bore to the face of said blades, of a pivoted plate restricting means mounted to swing upwardly from a point below the bottom end of the bore to an inner position to form wall means beneath the lower end of said bore of an area substantially the cross sectional area of the bore, whereby flow through said bore may be restricted to assure ejection of circulating fluid from the circulating passages at a relatively high velocity.

8. The combination with a drill bit having a bit body provided with exterior main cutting blades and having an axial bore with fluid circulating passages extendin from the bore to the face of said blades, of a pivoted plate restricting means mounted to swing upwardly from a point below the bottom end of the bore to an inner position beneath the lower end of said bore and thereby establish beneath said end a wall having an area substantially .the cross sectional area of the bore, whereby flow through said bore may be restricted to assure ejection of circulating fluid from the circulating passages at a relatively high velocity, said restricting means also functioning to deflect the fluid discharging from the well bore into direct contact with the surfaces of the main cutting blades adjacent and below the bottom end of the bore.

9. A drill bit including, a body having an axial bore extending therethrough, two main cutting blades on the exterior of said body, circulating passages extending from the bore of the body to the blades, whereby fluid circulated downwardly through the bore may flow through said passages and onto the blades to lubricate and wash the same, two core-breaking blades pivotally mounted on the lower portion of the body and disposed at substantially a right angle to main cutting blades, said core-breaking blades being adapted to be swung from an outer position completely out of alignment with the bore of the bit body to an inner position beneath said bore, and a deflector plate element secured to each core-breaking blade, said plate elements being so disposed that when the blades are in an inner position they co-act with each other to substantially close the lower end of the bore to restrict the flow therethrough and thereby assure ejection of the circulatin fluid from the circulating passages under a relatively high velocity, the deflector plate elements being posi- Vbcre extending therethrough, main cutting blades on the exterior of said body, core-breaking blades pivotally mounted on the lower portion of the body and arranged to swing inwardly beneath the open lower end of the bore, and means on said core-breakin blades for restricting the flow of fluid through the bore when said blades are in their inner positions, said restricting means also being so constructed as to function to deflect in volume the fluid which is discharged from the lower end of the bore laterally at a sharp angle and against the main cutting blades.

JOHN GORDON JACKSON.

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

UNITED STATES PATENTS Number Name Date 144,475 Phillips et a1. Nov. 11, 1873 1,542,172 Reed et a1. June 16, 1925 2,179,010 Creighton et al Nov. 7, 1939