US2641444A - Method and apparatus for drilling boreholes - Google Patents

Description

June 9, 1953 J. MOON 2,641,444

METHOD AND APPARATUS FOR DRILLING BOREHOLES Filed Sept. 3, 1946 2 Sheets -Shet 1 ATTORNEY METHOD AND APPARATUS FOR DRILLING BOREHOLES Filed Sept. s. 1946 J. MOON 2 Sheets-Sheet 2 June 9, 1953 I IINVENTOR.

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I, JWM VYW R 4 Patented June 9, 1953 METHOD AND APPARATUS FOR DRILLING BOREHOLES ames Moon, Altadena, Calif., assignor to Signal Oil and Gas Company, Los Angeles, Calif., a

corporation of Delaware Application September 3, 1946, Serial No. 694,561

This invention relates to a method and apparatus for drilling bore holes, and particularly to the drilling of drill holes to a predetermined gauge and also to the drilling of bore holes to traverse a predetermined course in the earth. In the drilling of bore holes by the rotary method so as to traverse av straight vertical path, it has been previously suggested that the drill pipe be advanced together with an accompanying straight guide casing in which'the drill tubeis supported for rotation. I

It has also been suggested that in drilling deviated bore holes the drill pipe be guided in a casing which has been previously bent to the curve which the drill tube is to traverse in drill? ing the bore hole.

This invention is an improvement in such methods and in such apparatus.

In such drilling procedure, in common with normal drilling inside of uncased holes where no guide casing is employed, it has been found desirable to limit the load on the drill pipe. The static weight of the drill pipe is frequently too great a load on the drill. The result is a bending and severe whipping and even corkscrewing, of the drill pipe. Such bending, whipping, and corkscrewing cause the drilling of a bore which is not true to gauge and in which large caves are created and also cause the bore hole to deviate in the wall of the bore. This whipping and corkscrewing also cause such reversals of the stress that a material shortening of the effective life of the pipe results.

In drilling in cased holes with advancing casing, the load which may be imposed on the drill 6' Claims. (Cl.- 255-1.s

through the jets of the drill at equal mud pump pressure.

Additionally, the abrupt change in tube wall thickness, particularly at the point where the stress changes from tension in the drill pipe to compression in the drill collar, is a. point of weakness, and since under modern drilling controls it is impossible for the driller to localize and maintain invariant the point where thisstress changes in phase from tension to compression, failure occurs at the juncture between the drill tube and is likewise limited, due to the large slenderness ratio of the column of drill pipe. It bends under load, whips, and corkscrews in the casing, causing similar damage to the casing and drill pipe and deviation of the bore hole.

It has therefore been the practice in drilling to limit the load on the drill by'supporting-the, weight of the drill pipe so that the drill pipe above the drill collar is in tension and only the weight of the drill collar is imposed on the drill. The use of drill collars for impartingweight to the drill and to give rigidity to the section of the drill string above the drill has imposed certain serious limitations. Such drill collars are substantially of the external diameter of the drill pipe, but in order to have great weight and be more rigid than the drill pipe, they are of much smaller internal diameter. This'imposes a serious back pressure on the circulating drilling fluid and reduces the velocity of the drilling fluid the drill collar. This also cause variations in stress throughout the entire drill stem.

Additionally, in drilling with an advancing casing one of the difficulties is to maintain the relationship between theend of the casing and the drill such that the drill does not advance too far ahead of the casing to be properly guided thereby. 3 I have developed a method and apparatus for drilling which overcome these difi'iculties.

In my method of drilling, employing the apparatus of my invention, I load the drill which is, as conventional, attached to the end of the drill pipe, not by the drill pipe, but by guide casing, whose advance is controlled independently of the advance of the drill string, so that the drill is advanced by the load of the casing against a restraining ,force on the drill pipe imposed at or near the other end of the drill pipe which tends 'tohold the drill pipe back. The load imposed on the drill by the casing is held sufliciently greater than the restraining force by the independently controlled casing advancing means to advance the drill at the desired rate.

The drill stem from the surface of the ground to the point of application of the casing load is maintained in tension. This casing load is applied immediately above the drill so that drill collars are not needed, or if needed are not relied upon to load the drill.

For this reason the point of application of weight on the drill remains constant and no section of the drill stem is subjected to stresses which fluctuate in phase.

Since drill collars are largely eliminated, or may be completely eliminated, the restriction on mud flow which they impose is also eliminated.

The phenomenon of destructive forces in drill pipe caused by these uncontrolled vibrations results in enormous shock loads which in turn greatly shorten the useful life of the drill, and in many cases causes a permanent deformation of corkscrew character in the drill pipe.

' By loading the drill pipe with casing according to my invention, a large reduction of the bending forces in the pipe results, so that the positioned in the openings 50a, making a sliding fit therein. The head 52 is recessed to receive the bolt '53 which holds the flexible cup washer '55. The spring 54 is mounted between the end of the chamber 50 and Washer 55. The casing an. internal collar-.56 welded thereto. The collar terminates in ashouider 51.. The drill is connected to the shaft 24 at 58.

With the drill string assembled and in position, as shown in Fig. l, but with the casing reby the: hydraulic jacks 9 so that the fluid in the annulus betweerf the-easing arid the;

wall. All of these factors aid the casing ill-9315* sorbing these loads without. damage.

These objects and advantages will be clear to those skilled in the art by the following description when taken together with thedrawings, in

which Fig. 1 is a view of the drill string according to o my invention in position in drilling a well;

. F g. .2 is a detail of. the drill and thrust head.

shown n Fig. 1"; Fig, 3 is a vertical section through. the thrust head;

Fig. 4: is a section taken on. line 4-4 of Fig. 2;. and;

Fig- 5 is. a. section taken. on. the. line 5---& of Fig, 3.

In: well; bore l is positioned the conventional conductor pipe carrying a packer seal 3 and a mud inputipipel The. packer may be. of the designshown. more. fully in my copending application Serial No. 653,875,.filed March 12, 1946,, now abandoned, is herewith. incorporated by reference.

Aca'sing 5. passes through the packer e and is supported on. a yoke 6 carrying supporting slips T, Theyoke is advanced and retractedby piston rods. 8 of hydraulic. jacks 9.. The drill string composed v of. a conventional kelly to and; drill tubing. H isrotated by a conventional rotary table t2 and supported by the. swivel. t5, block I24 and line 5 passing over the crown. block. (6 ot a derrick. IT and the. line 5' passing over. the conventional. hoist 18;

In place: of; or in. addition. to the conventional drill collars the drill. tubing. carries adjacent the drill ISl' carries conventional. expansible and retractable reamers 20; the. thrust head if, carrying the pins? 22. The load of. the casing 5 istransmitted to the pins by means oil the casing collar 23;

- The thrust head. is composed of a hollow shaft 24 which isconnected via threads 25 and tool joint 26 to the drilltubing IL. This construction permits of the tension. loading. oi the drill pipe and is a.secure connection. under such. tension. The collar 23, formed with. lugs 28a, has ashoulden 39' which is mounted on shoulder oil the shaft 24 by means of bearingsv 4i. i

The collar 23' is spaced from. the shaft. 2.4 and the space is sealed at the top by means of packers 3Q retained in packer ring 29.. A hearing 33' retained in packer ring 29 by meansoi shoulders 34 and by shoulder 32 on'collar Z8. A further seal! is provided by packer 34 retained. by shoulder to and ring 35. Sealing is further provided. bypacker so retained by shoulder 31 and. ring 38. A further bearing. 44 is retained on ring. 42 by means of. shoulder 43 and end. shoulder 43 of packer ring. 45'"- in. which is positioned the packer 41 retained by ring. 48-.

The shaft 24' carries ports 21 which. are in registry thechamber Mano recesses 50m in shoulder 51 is raised above the pins 5|, the mud circulating through 4, down the tubing 1 l and.

' through. the iets of the drill, exerts a pressure Iii on the washers 5a to move the pins 5| outward against the spring 54. The casing is then lowered the shouldez 51 engages the head 52, as shown. in Fig. 2. The weight of the casing is thus imposed on the pins 5|. The mud is also circulated through line 4 down the annulus. be-

the casing and; bore wall and joinsthe mud descending through the drill pipe it, re

. turning; up between the casing and drill pipe to the collar 28= and lugs 28a. Pins. 54', whose axes are atoll to themes of: thesha 2. a e

discharge through line I la to the-mud pit.

The load imposed; by the casing is regulated by the load impose-d byth'e hydraulic jacks which can. cause. the advance of the casing and may be controlled independently of the advance of the drill string. more or less of the static weight of the casing is imposed on the pins" by the jacks. If the jacks impose" an upward thrust on the yoke, some oi. the static: load is taken up by this upward thrust or if the jacks impose a downward thrust on. the yoke, this additional load is added to the weight of the casing.

Part or all. of the weight of the? drill pipe may be taken up by the tension on line to. The net static load on the drill is thus the difference icetween the weight of the drill pipe and the tenin pounds.- on the line f5, e-., the load on the hook. In drilling ahead. this load is less than the static load by the amount of this pull which acts as a retarding fierce; or upward thrust on the casing. It is thus possible. to determine the load conditions on the drill during drilling when the drill is by the. casing and the drill pipe. In order to minimize friction; drilling fluid is circulated through input line 4 anddown the annulus between the casing and the bore h'oie and circulated together with the mud passed through the drill pipe; back up inside the casing. This not only reduces the friction between thecasing and the bore hole to a negligi-bi-e degree,

' but also has the addit"I'on'al advantages set forth in the co-pen'ding application, Serial No. 653 ,8'75 With the required load imposed by the casing on the head, the drill pipe and drill are rotated in the bearings". A restraining force is imposed by the line E5 in amount. greater than the static of the: drill. string above the thrust collar; so that: the: drill pipe above the thrust collar is. throughout its; length. entirely tension. The entire compression load. on; the thrust collar and. drill is the load imposed by the casing. The drill pipe is: thus pulled into the Home against therestraining force of: the. line. This'restraining fierce. is less than the static weight of the casingand drill pipe,- ignoring friction may lie-negligible in view of the lubricating effectof the mud and the enlargement of the: bore causedv by the. reamer 201, as shown. in Fig: 1. p This diiierence constitutes. the load on the bit. I Witl i; the driI-Lpipe. entirely tensionthe drill conventional tensiorneter in the line.

pipe is not under any flexure load and rotates with substantially no whip or winding up.

Unlike conventional drilling operations, the load on the bit is a steady load. The drill pipe does not jump up and down in the hole as it does in present practice. The load on the bit is localized and remains stationary at the lugs 54 so that no change in load phase from tension to compression occurs at any joint or plane in the drill assembly.

Since the load on the drill is an external load and not due to any weight imposed by drill collars or the drill tubing, the restriction imposed by the restricted bore of the drill collars is avoided and the back pressure on the circulating mud is reduced.

When the drill tubing is supported on a line 15, the load on the line may be measured by a Instead of supporting the drill tubing on a line, it may be supported and moved by means of hydraulic cylinders as described in my co-pending app-lication identified above.

While I have described this invention as ap plied to drilling of a vertical bore, it is also applicable to the drilling of horizontal bores or deviated bores by the drilling procedures described in my co-pending application Serial No. 949,719, filed January 1949, now abandoned, or by the process and apparatus oi the copending applications of Garth L. Young, Serial No. 629,543, filed November 19, 19.45, now abandoned, and Serial No. 619,749, filed October 2, 1945, now Patent No. 2,565,794 issued August 28, 1951.

In the previous discussion, I have described the application of my method and apparatus as applied to the preferred embodiment wherein the drill pipe is entirely in tension and substantially the entire compressive load is that resulting from the loading of the pins by the casing. sired for any reason, the drill may also be loaded by the drill pipe by reducing the amount of tension on the line is so that part of the static load of the drill pipe is transmitted to the drill.

While I have described a particular embodiment of my invention for the purpose of illustration, it should be understood that various modi fications and adaptations thereof may be made Within the spirit of the invention as set forth in the appended claims.

I claim:

1. A method of rotary drilling, which comprises rotating and advancing a string of drill pipe to which a drill is attached. at one end thereof in the earth to form a bore hole, advancing a casing in said bore hole independently of and simultaneously with the advance of said string of drill pipe, transferring the weight of said casing to said drill during, drilling, and advancing and simultaneously restraining the drill pipe against said advance by a restraining force imposed near the other end of said drill string, whereby the load of said casing advances said string of pipe against said restraining force.

2. A method of rotary drilling, which comprises rotating and advancing a string of drill pipe to which a drill is attached at one end thereof in the earth to form a bore hole, advancing a casing in said bore hole, independently of and simultaneously with the advance of said string of drill pipe, imposing a thrust load on said casing, transferring the thrust of said casing to said drill pipe during drilling, and advancing said drill pipe and also simultaneously restraining the drill pipe against said advance by a restraining If deforce near-the other end of said drill pipe, whereby the thrust of said casing advances said drill pipe against said restraining force.

3. A drilling device, a comprising a thrust collar, a central bore in said collar, a hollow shaft rotatably mounted in said central bore of said thrust collar, means for connecting one end of said shaft to a string of drill pipe, means for con necting the other end of said shaft to a rotary bore hole drill, a plurality of extensible pins in said collar, the axes of said pins being positioned at about to the axis of said shaft.

4. A rotary drilling device, comprising a thrust collar, a hollow shaft coaxial with said thrust collar, bearings between said shaft and said collar, packing between said shaft and said collar, means for attaching said shaft to the drill pipe of a rotary earth drilling device, means for attaching the other end of said shaft to the drill of said rotary drilling device, a port in said shaft, a bore in said collar in fluid communication with said port in said shaft, 2. pin slidably positioned in said bore, and a spring mounted in said bore, hydraulic means for moving said pin against said spring upon the imposition of fluid pressure in said shaft to move said pin in said bore to extend said pin exteriorly of said collar.

5. In a rotary earth bore hole drilling device for Wells, a string of drill pipe, means at the surface of the ground for rotating and advancing said string, a drill attached to the end of said drill pipe, a thrust collar coaxially mounted on said drill pipe adjacent said drill, bearings between said thrust collar and said drill pipe, pins movably positioned in bores in said thrust collar, means for extension of said pins outwardly,

from said collar, a casing concentrically mounted with said drill pipe, and means at the surface for suspending and advancing said casing, said casing resting upon said pins when said pins are extended externally of said thrust collar.

6. In a rotary earth bore hole drilling assembly in combination, drill pipe, means at the surface of the ground for rotating and advancing said drill pipe, a drill mounted at the end of said drill pipe, a thrust collar concentrically mounted upon said drill pipe adjacent said drill, bearings between said thrust collar and said drill pipe, a bore in the wall of said drill pipe, a plurality of bores in said thrust collar in fluid communication with the bore in said drill pipe, pins resiliently mounted for movement in the bore of said thrust collar, a casing concentric with said drill collar, means at the surface for supporting and advancing said casing, a collar mounted upon said casing adapted to rest upon said pins of said thrust collar when said pins are extended in said bore of said thrust collar, means for extending said pins in said bore of said thrust collar upon the imposition of fluid pressure in said drill pipe.

JAMES MOON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 804,092 Brants Nov. '7, 1905 1,147,898 Seitz July 27, 1915 1,166,011 Shaffer Dec. 28, 1915 1,391,626 Gilthorpe Sept. 20, 1921 1,894,039 Hill Jan. 10, 1933 2,100,419 Wright Nov. 30, 1937 2,112,254 Stokes Mar. 29, 1938 2,242,279 Young May 20, 1941 2,292,126 Isley Aug. 4,1942

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