US3318398A

US3318398A - Drill collar stabilizer

Info

Publication number: US3318398A
Application number: US379100A
Authority: US
Inventors: Ray F Fry; Owen Kelly
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-06-30
Filing date: 1964-06-30
Publication date: 1967-05-09
Anticipated expiration: 1984-05-09

Description

May 9, 1967 D. R. OWEN 3,318,398

DRILL COLLAR STABILI ZER Filed June 30, 1964 fla/e 7?. Owen INVENTOR.

W R LM ATTOF/VE VJ United States Patent ()filice 3,318,398 Patented May 9, 1967 3,318,398 DRILL COLLAR STABILIZER Dale R. Owen, deceased, 311 Claymore Drive, Lafayette,

La. 70501; Ray F. Fry, as tutor of Lauren Owen,

Tracy Owen, and Kelly Owen, minor children of said Dale Owen Filed June 30, 1964, Ser. No. 379,100 12 Claims. (Cl. 175-323) The invention concerns a stabilizer suitable for con nection and use in a drill string, particularly for connection to one or more drill collars in a drill string.

Stabilizers are frequently employed during the drilling of wells to center the drill collars in the well bore and provide better alignment in the hole being drilled. The stabilizers usually comprise a tubular body having means at each end for connection in the drill string and a plurality of blades or rollers disposed circumferentially on the external surface of the tubular body. The blades or rollers usually extend from the tubular body for a distance sufficient to permit stabilization in the Well bore, for example, for a distance such that the diameter of the outside circumference of the blades or rollers is about equal to or slightly less than the diameter of the well bore or the outside diameter of the drill bit.

Stabilizers when suitably placed in a string of drill collars can keep the collars centered in the hole and minimize sidewise drilling of the bit, thereby helping to effect a substantially straight hole. Stabilizers can also help to prevent sticking of the drill collars in the well bore since the stabilizers keep the surfaces of the collars away from the wall of the well bore. Stabilizers are also useful when placed a suitable distance from the drill bit to straighten a slanting well bore more towards vertical because of the pendulum effect achieved when the weight of drill collars below the stabilizer is rather large.

The invention provides a novel stabilizer construction which in various embodiments exhibits improved characteristics over the stabilizers known heretofore. One embodiment exemplifying the invention comprises a tubular body; means at each end of the body for permitting connection in a drill string; at least two substantially helical bars or blades fixedly mounted on and circumferentially spaced around the external surface of the body; and at least one ridge substantially longitudinally disposed on the external surface of the body between each adjacent pair of the bars near the ends of the bars which trail during entry into a well bore, this ridge minimizing circumferential erosion of the body by drilling fluid around the tubular body immediately above the trailing ends of the bars during entry into the well bore.

Preferably the stabilizer defined above has ridges made of hard metal which extend longitudinally of the body from a point below the trailing ends of the bars to a point above the trailing ends of the bars for a distance sufficient to minimize circumferential erosion of the body by a drilling fluid. Since commercial stabilizers are usually between about 3 feet and above 5 feet long depending on the size of the well bore and the size of the drill collar with which the stabilizer is to be associated and the helical bars or blades are between about inches and about 20 inches long ordinarily a ridge :between about 3 inches and 6 inches long will minimize circumferential erosion sufficiently. Likewise, for most commercially known uses the ridge may be up to about /2 inch wide and up to about /2 inch high a ridge of about 41 to about A inch high being preferred.

The bars or blades are preferably disposed to provide coverage around the external surfaces of the body of about 360, although coverage of between about 345 and about 375 is satisfactory. The bars are preferably made of metal sufiiciently soft topermit milling thereof,

such as during washover operations, this metal preferably being softer than the metal of the tubular body. For example, the tubular body may be made of heat-treated hard steel, as is common in the art, and the bars or blades may be made of mild steel. In addition, the external surfaces of the bars radially of the body are preferably hardfaced by suitable techniques, such as by hardfacing with alloys of suflicient hardness or tungsten carbide. A preferred embodiment in accordance with the invention also includes hardfacing on the end surfaces of the bars which lead during entry into the well bore, this hardfacing preferably being harder than the softer metal in the bars.

The bars are preferably disposed in a helical direction which upon rotation of the stabilizer during entry thereof in a well bore is similar to that of a right-hand screw. This provides a pumping action and helps force drilling fluid up between the bars to maintain a clear passage therethrough and prevent collection of muds and the like. A righthand helix can also act as a reamer, thereby helping to maintain hole gauge. The bars should be wide enough to provide sufficient lateral bearing surface but thin enough to permit sufiicient passage of drilling fluid thereby.

Preferably, three bars or blades are spaced around the external surface of the body symmetrically with the external surfaces of the bars radially of the body each covering in a direction peripheral of the body about thereof, thus providing 360 coverage over the external surface of the tubular body.

Another embodiment of the invention comprises a tubular body, means at each end of the body permitting connection of the drill string, three substantially helical bars mounted around the external surface of the body, and a hard metal ridge substantially longitudinally disposed on the external surface of the body between each adjacent pair of bars from a point below the ends of the bars which trail during entry into a well bore to a point above the ends for a distance sufficient to minimize circumferential erosion of the body by drilling fluid, the tubular body having an outside diameter, at least under the bars in the ridge, sufficiently less than the outside diameter of an adjacent pipe joint, to the lower end of which the stabilizer is to be connected, to permit milling of the bars during washover operation without material interference from the ridge. The tubular body may have an outside diameter along its entire length smaller than the outside diameter of the adjacent pipe joint, or it may 'be made sufficiently smaller only under the bars and the ridge to permit convenient milling.

The bars or blades are preferably welded on the tubular body in accordance With conventionally known techniques although the bars may be mounted in grooves or slots and then bolted or otherwise held on. Welding, however, provides a more permanent bonding and consequently minimizes breakage of the stabilizer and resultant loss of metal parts in the hole.

In the drawing:

FIG. 1 is an elevational view of an embodiment of a stabilizer in accordance with the invention;

FIG. 2 is a top plan view taken along the line 2-2 in FIG. 1; and

FIG. 3 is a schematic perspective view of the stabilizer shown in FIG. 1 in place in a drill string.

With reference. to FIG. 1 and FIG. 2 in the drawing, the stabilizer there shown comprises a'tubular body 10 having a threaded projection 12 at one end and a threaded socket 14 at the, other end, the projection 12 and the socket 14 being of a size suitable for connection in a drill string, particularly for connection in a string of drill collars or between a drill collar and a drill bit. Three

bars

16, 18,-and 20 are welded on the outside surface of the tubular body 10 and are substantially helical in shape with a helical direction similar to that of a righ hand' screw when the stabilizer is entering awell bore.

The bottom ends of the

bars

16, 18, and 20 (bottom end 22 of bar 16 being the only one shown) and the external surfaces of the bars radially of the tubular body 10, that is, the extreme outside bearing surfaces, are hardfaced to provide durability. The other exposed surfaces of the

bars

16, 18, and 20 are not hardfaced in order to permit a milling tool to mill the bars away if a washover operation is necessary.

Hard metal ridges

24, 26, and 28 are disposed on the outside of the tubular body 10, each being located between an adjacent pair of bars near the trailing ends of the bars. As shown, the

ridges

24, 26, and 28 extend from a point below the trailing ends to a point above the trailing ends for a distance sufiicient to minimize circumferential erosion around the tubular body 10 sufliciently as drilling fiuid passes up the outside of the tubular body 10 between the bars.

Ridges

24, 26, and 28 may be made by welding a ridge of sufficiently hard material on the tubular body 10. The

bars

16, 18, and 20 may be made from rectangular bar stock rolled into a substantially helical shape, cut to length, and then 'welded on the tubular body 10 in the proper places. The bar stock is preferably rolled to form 24 as well as the other ridges thereon, and mill away the

bars

16,18, and 20 (bar 20 not being shown) without the necessity of milling the ridges and without material interference from the ridges. The reduced diameter also eliminates the necessity of milling the welds holdings the bars on the tubular body. Usually, a reduction in diameter of between about A; to .about 1%: inch or more will be satisfactory.

The combination of hardened ridges to minimize circumferential erosion around the body 10 and a decrease in the diameter of the body 10 to avoid interference of the ridges during a milling operation provides a stabilizer havingiunproved characteristics while avoiding the introduction of characteristics undesirable .during a milling operation. If a stabilizer in accordance with the inventionis made sufiiciently short, for example, below about feet for most commercial operations, and of relatively inexpensive materials, it possesses the desirable characteristic of being economically disposable after the bars or blades wear out, thereby eliminating inconvenient repair at a well site. Suitable'materials of construction will be apparent to those persons in the art, which materials of course must be selected in view of conditions expected during a particular use,

What is claimed is:

1. A stabilizer suitable for connection in a drill string, said stabilizer comprising a tubular body; means at each end of said body for permitting connection in a drill string; at least to substantially 'helical bars fixed mounted on and circumferentially spaced around the external surface of said body; and at least one ridge substantially longitudinally disposed on said external surface of said body between each adjacent pair of said bars near the ends of said bars which trail during entry into a well bore.

2. The stabilizer defined in claim 1 wherein said ridge is made of hard metal and extends longitudinally of said body from a point below the trailing ends of said bars to a point above the trailing ends of said bars for a distance suflicient to'minimize circumferential erosion of said body by drilling fluid.

3. The stabilizer defined in claim 1 wherein the external surfaces of said bars provide coverage of about 360 around the external surface of said body.

4. The stabilizer defined in claim 1 wherein each of said bars is made of metal sufficiently soft to permit milling thereof with the external surface of each of said bars radially of said body and the end surface of each of said bars at the end which leads during entry into a well bore being harder than said metal.

5. The stabilizer defined in claim 1 wherein said body is made of metal, and each of said bars is made of a metal softer than the metal of said body to permit milling, with only the external surface of each of said bars radially of said body and the end surface of each of said bars at the end which leads during entry into a well bore being hardened to be harder than the softer metal of said bars.

6. The stabilizer defined in claim 1 wherein said substantially helical bars are disposed in a helical direction which upon rotation of said stabilizer during entry thereof in a well bore is similar to that of a right-hand screw.

7. A stabilizer suitable for connection in a drill string during rotary drilling; said stabilizer comprising a tubular body; means at each end of said body for permitting connection in a drill string; three substantially helical bars fixedly mounted on and symmetrically and circumferentially spaced around the external surface of said body, each of said bars having an external surface radially of said body covering in a direction peripheral of said body about of the periphery of said body, said bars being formed of metal sufiiciently soft to permit milling thereof with only the external surfaces of said bar radially of said body and the end surfaces of said bars at the ends which lead during entry into a well bore being hardened to be harder than said metal; and a ridge disposed substantially longitudinally on said body be tween each adjacent pair of said bars near the ends of said bars which trail during entry into a well bore.

8. The stabilizer defined in claim 7 wherein said ridge is made of hard metal and extends longitudinally of said body from a point below the trailing ends of said bars to a point above the trailing ends of said bars for a distance sufficient to minimize circumferential erosion of said body by drilling fluid.

9. The stabilizer defined in claim 7 wherein said substantially helical bars are disposed in a helical direction which upon rotation of said stabilizer during entry thereof in a well bore is similar to that of a right-hand screw.

10. A stabilizer for connection in a drill string, said stabilizer comprising a tubular body; means at each end of said body for permitting connection in a drill string; three substantially helical bars fixedly mounted on and circumferentially spaced around the external surface of said body; and a hard metal ridge substantially longitudinally disposed on said external surface of said body between each adjacent pair of said bars from a point below the ends of said bars which trail during entry into a well bore to a point above these ends for a distance suificient to minimize circumferential erosion of said body by drilling fluid; said tubular body having an outside diameter, at least under said bars and said ridge, sufficiently less than the outside diameter of a pipe joint, to the lower end of which said stabilizer is to be connected, to permit milling of said bars without material interference from said ridge.

11. The stabilizer defined in claim 10 wherein said bars are made of a metal softer than said body and have hardfacing on only the external surfaces of said bars radially of said body.

12. The stabilizer defined in claim 10 wherein said bars are made of a metal softer than said body and have hardfacing on only the external surfaces of said bars radially of said body and the ends of said bars which lead during entry into a well bore.

References Cited by the Examiner CHARLES E. OCONNELL, Primary Examiner.

JAMES A. LEPPINK, Examiner.

Claims

1. A STABILIZER SUITABLE FOR CONNECTION IN A DRILL STRING, SAID STABILIZER COMPRISING A TUBULAR BODY; MEANS AT EACH END OF SAID BODY FOR PERMITTING CONNECTION IN A DRILL STRING; AT LEAST TO SUBSTANTIALLY HELICAL BARS FIXED MOUNTED ON AND CIRCUMFERENTIALLY SPACED AROUND THE EXTERNAL SURFACE OF SAID BODY; AND AT LEAST ONE RIDGE SUBSTANTIALLY LONGITUDINALLY DISPOSED ON SAID EXTERNAL SURFACE OF SAID BODY BETWEEN EACH ADJACENT PAIR OF SAID BARS NEAR THE ENDS OF SAID BARS WHICH TRAIL DURING ENTRY INTO A WELL BORE.