Turbulent flow drill collar

United States Patent uh_3,554,307

[72] Inventor Nolen A. Yount Beeville, Tex.

[21] Appl.No. 838,764

[22] Filed July 3,1969

[45] Patented Jan. 12,1971

[73] Assignee W.E. Eeds

Beeville, Tex. a part interest

3,338,069 8/1967 Ortloff.......................... 64/1

3,360,960 1/1968 Massey......................... 64/1

FOREIGN PATENTS

206,517 2/1909 Germany...................... 175/320

Primary Examiner—James A. Leppink

Attorneys— Clarence A. O’Brien and Harvey B. Jacobson

[54] TURBULENT FLOW DRILL COLLAR

Claims, 3 Drawing Figs.

[52] U.S.C1........................................................ 175/323,

64/1

[51] Int. Cl.........................................................F21b 17/00

[50] Field of Search................... 175/320,

323; 64/1

[56] References Cited

UNITED STATES PATENTS

3,146,611 9/1964 Fox.............................. 64/1

3,175,374 3/1965 Toelke......................... 64/1

ABSTRACT: A tubular drill string member having grooves formed in the outer surface thereof extending circumferentially thereabout and longitudinally thereof. The grooves include short sections or lengths of first groove portions which generally parallel the longitudinal centerline of the tubular drill string member or drill collar and short sections or lengths of second groove portions which are inclined generally 15° relative to a plane normal to the longitudinal centerline of the drill collar. The second groove portions interconnect the adjacent ends of adjacent first groove portions and the first and second groove portions of each groove are disposed generally in a helical path extending along and about the corresponding drill collar.

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PATENTED JM121871

3,554'307

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3,554,307

2

TURBULENT FLOW DRILL COLLAR

A drill collar is a tubular member of a drilling string used in the drilling of oil, gas and water wells. The collar is made of high grade steel and serves as a portion of the tubular drilling string and to add weight to and stiffen at least the lower por- 5 tion of the drilling string immediately above the drilling bit.

A drill colldr is made in various diameters and wall thicknesses whereby the :w eight of the drill collar per unit of its length may vary greatly. Because drilling bits have been greatly improved it is now possible to increase the weight on the drilling bit so as to increase the rate of penetration of the bit. The weight on the bit is controlled, to a great extent, by the size and number of drill collars disposed above the bit. As additional drill collars are added to the bottom end of a drill string, the friction of the drill collars in the well bore is increased. The outer diameter of the collars used is less than the Outside diameter of the associated drill bit whereby drilling fluid or mud being pumped through the drill bit is permitted to move upwardly in the well bore about the drill collars toward the upper end of the well bore.

It has been found desirable at times to decrease the opening in the drilling bit through which the drilling fluid passes resulting in a decrease in the amount Of drilling fluid Which may pass through the bit and upwardly along the Outer surfaces of the drill collars. The reduction in flow of drilling fluid through the bit reduces the speed Ofthe fluid upwardly about the drill collars toward the upper end of the bore and this reduction of speed of movement of the drilling fluid toward the upper end of the bore the cuttings made by the bit and which flow upwardly with the drilling fluid to the upperend ofthe bore tend to ball Or stick together. This can increase hydrostatic pressure in the well bore arid the increase in hydrostatic pressure can cause a breakdown in formation porosity and loss of drilling fluid. When drilling fluid loss is experienced there is a great possibility Of sticking the drilling string in the hole. A stuck drillirig string is freed only after expensive fishing jobs arid it sometimes causes a well to blow out.

The object of this invention is to provide a drill collar serving to create a turbulent flow of drilling fluid about the drill collars during return of the drilling fluid to the upper end of the well bore. This turbulent flow will increase the speed of the drilling fluid and the cuttings as they move toward the upper end of the bore and it will keep the drilling cuttings from bailing up arid sticking. Further, it will decrease the hydrostatic pressure in the bore.

Another object of this invention is to provide a tubular drill collar which will serve to prevent mud cake from building up in the well bore throughout a formation with porosity.

The turbulent flow drill'collar of the instant invention further has as its objects the general Objects of a drill collar such as that disclosed in U.S. Pat. No. 2,999,552.

A final object of this invention to be specifically enumerated herein is to provide a drill collar in accordance with the preceding objects and which will conform to conventional forms of manufacture, be of simple construction and easy to Use so as to provide a device that will be economically feasible, long lasting and relatively trouble free in operation.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction arid operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to likeparts throughout, and in which:

FIG. 1 is an elevational view of the improved drill collar of the instant invention with portions of the upper end thereof being broken away and illustrated in vertical section;

FIG. 2 is an enlarged fragmentary vertical Sectional view taken Substantially upon the plane indicated by the section line 2-2 of FIG. 1; and

FIG. 3 is an enlarged horizontal sectional view taken substantially upon the plane indicated by the section line 3-3 of FIG. 1.

⁵⁵

Referring now more specifically to the drawings, the numeral 10 generally designates the drill collar of the instant invention. The collar 10 is generally conventional in that One end thereof is internally threaded as at 12 and the other end thereof is externally threaded as at 14. However, the collar 10 includes a pair of grooves referred to in general by the reference numerals 16 and 18 which extend along and about the drill collar 10 in generally helical paths. Each of the grooves 16 includes first groove portions 20 and second groove portions 22. The first portions 20 generally parallel the longitudinal center line of the drill collar 10 and the second groove potions are inclined approximately 15° relative to a plane normal to the longitudinal center line of the drill collar 10. Each groove portion 22 interconnects the adjacent erids of a pair of adjacent first groove portions 20 and in this manner substantially all portions of the grooves 16 and 18 either generally parallel or are disposed substantially normal to the direction of movement of adjacent peripheral portions of the drill collar during rotation ofthe latter.

As can best be seen from FIGS. 2 and 3 of the drawings the cross-sectional shape of the groove portions 20 and 22 is dissimilar. The groove portions 20 are substantially V-shaped in cross section including a pair of relatively inclined opposite sidewalls 26 and 28. The groove portions 22 also include relatively inclined opposite sidewalls 30 and 32, but the inner marginal edge portions of the sidewalls 30 and 32 are connected by a bottom wall 34.

It will be noted that the relatively inclined sidewalls 26 and 28 of the groove portions 20 do not offer any edges Which would tend to cause displacement of the associated drill String in either longitudinal direction upon engagement of the portion of the drill collar 10 about one of the grooves 20 with the walls of the well bore during rotation of the drill collar 10. Further, the groove portions 22 are free of cutting edges and are short in circumferential extent, Whereby any tendency of the grooves 22 to longitudinally displace the drill collar 10 during rotation of the latter by contact with the well bore will be brief.

The groove portions 22 are inclined 15° relative to a plane normal to the longitudinal Center line of the drill collar although the inclination of the groove portions 22 may vary 2 or 3°, or possiblymore, above and below an inclination of 15°.

The particular configurations of the grooves 16 and 18 prevent the drilling cuttings from balling up and sticking by increasing the turbulence of the drilling fluid as it passes toward the top of the well bore. Further, the hydrostatic pressure of the drilling fluid within the well bore is reduced and mud cake is prevented from building up in the well bore. Also, the formation of the grooves 20 and 22 provide a means to insure that drilling fluid is disposed On all sides of the drill collar 10. Thus, the drill Collar 10 is lubricated and any tendency for the drill collar to stick in the well bore is reduced.

Further, by having the groove portions 20 parallel the longitudinal axis of the drill collar 10 and the groove portions 22 disposed substantially normal to the longitudinal axis Of the drill collar 10, there are no outer surface portions of the drill collar which would tend to cause rotation of the lower end of the drill string as it is being lowered into the bore. It is not unusual for drill strings having drill collars thereof provided with smoothly curving helical grooves to cause a portion ofthe drilling string to be unthreaded while the drill string is beihg lowered into the well bore. When this happens, the lower end of the drilling string drops to the bottom of the well bore and must be retrieved by specific fishing tools lowered into the bore.

By having the grooves 16 and 18 “stepped,” there is substantially no tendency for the lower end of the drilling string to unscrew from the upper end of the drilling string aS the string is being lowered into the well and portions of the lower end Of the string contact the well bore.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is

3,554,307 not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.