US 3318397 A
Description (OCR text may contain errors)
May 9 1967 M 8 4V N 0 7 H Filed Oct.
.J DE WAYNE COMBES APPARATUS FOR USE 1N WELL DRILLING United States Patent 3,318,397 APPARATUS FDR USE 1N WELL DRILLING John De Wayne Combes, New Orleans, La., assigner to Chevron Research Company, a corporation of Delaware Filed Oct. 6, 1964, Ser. No. 401,870 5 Claims. (Cl. 175-73) This invention relates to an improved apparatus for drilling wells and more particularly this invention relates to apparatus useful to maintain the desired line of hole direction by assisting in preventing hole deviation caused by rotation of the drill string.
A particular object of the present invention is to provide an improved =apparatus for alleviating the tendency of a rotary drilled hole to drift off a desired line in a formation because of the frictional forces caused by rotating the drill string.
As is known in the well drilling art, a drill bit is caused to move down into the earth by rotation of a string of pipe to which the drill bit is connected. Drilling fluid, commonly called drilling mud, is circulated down the drill pipe through openings in the bit and up the annulus between the outside of the drill pipe and the well wall to remove cuttings and to serve other functions such as lubricating the bit. Thus a hole is made by rotating the drill bit against the drilling face to break oi chips from the drilling face. The chips are carried to the surface by means of the drilling mud.
It is common to rotary drill wells to depths of 10,000 feet and more. After a hole has progressed some distance into the ground there is a great length of pipe needed to rotate the bit. The rotating action imparted to the bit often causes the bit to drift olf the desired line of the hole direction which might, for example, be vertical. Once a hole has drifted or curved olf the line it is an expensive and time-consuming operation requiring whipstocking or other techniques to put it back on line.
The problem of hole drifting is particularly serious in directionally drilled holes. A directional hole is one that has been purposely turned from the vertical. As is known in the art it is often desirable to drill a directional hole. A method of directional drilling is described and claimed in U.S. Patent No. 2,873,092 issued Feb. l0, 1955, to Roy P. Dwyer. One of the major diiculties encountered in drilling a directional well is the difficulty in maintaining the desired direction of the hole after the course of the hole has been changed land it is desired to drill a straight section of hole in the new direction at some predetermined angle from the vertical. The dimculty in keeping the hole on line is caused by the tendency of the bit to walk ott line.
Most rotary drilling is done by rotating the bit in a right-hand direction. As the drill bit is rotated in a righthand direction there is a tendency for the bit to drift to the right due to the friction-al forces between the bit and the earth. This phenomenon is known as right-hand walk The tendency of the bit to drift or walk is particularly noticeable when a relatively straight position of a directional hole is being drilled. It is often desirable to drill a hole having a direction with as much as 60 or more deviation from vertical. When it is desired to drill a straight hole by rotation at this angle the frictional forces which cause the bit to walk are often accentuated. It has been estimated that as rnuch as 90% of the time lost in drilling directional wells is due to the problem of correcting hole deviation due to right-hand walk. Heretofore the principal methods of counteracting right-hand walk were jetting hook-ups, special bits and whipstocks. Various hole centralizers and stabilizers have also been tried. However, none of the methods used heretofore have been entirely satisfactory and there ICC is need for a method and apparatus useful in preventing hole deviation from a desired line.
The apparatus of the present invention includes a stabilizing member connectable above a rotary bit for rotation about an axis parallel to or the same as the longitudinal axis of a drill bit. The stabilizing member is rotatably mounted above the drill bit and means are provided to rotate the stabilizing member in a direction opposite to the direction of rotation of the drill bit. The counteracting force provided by the rotating stabilizing member assists in overcoming the forces which tend to cause the bit to Walk and thus aids in preventing drift in the hole as the well is drilled.
Further objects and advantages of the present invention will become apparent from the following detailed discussion read in light of the accompanying drawing which is a part of this specification and in which:
FIGURE 1 is a schematic representation of one arrangement of apparatus suitable for carrying out the present invention;
FIGURE 2 is a sectional view taken at line 2-2 of FIG. 1 and is useful in understanding the present invention;
FIGURE 3 is a longitudinal View, partially in section, illustrating the preferred embodiment of apparatus of the present invention;
FIGURE 4 is a sectional view taken at line 4-4 of FIG. 3.
With reference to FIG. l, a well 20 is being drilled into the earth 22 by means of rotary bit 23. The bit is connected to drill string 25 which is rotated by means of rotary table 57. Drilling uid is supplied to the interior of drill string 25 from sump 27 by means of pump 28 through line 29. The drilling mud is circulated to the bottom of the well 20 through openings in the bit 23 and is returned up annulus 30, then through blow out preventor 56 and fluid line 3l to the mud sump 27.
The direction of well 20 has been changed by diverting the well in the portion indicated by the numeral 58. There are many well-known reasons why such a deviationmight be desirable. The deviation from the vertical may be as much as 60 o'r more. Hole deviation can be accomplished by any suitable means, such as the method of the patent mentioned above or by means of whipstocks or other implements Well known in the art. The present invention is directed to assisting in keeping the straight section of the hole on line after the hole has been diverted to the new direction. Thus it is desirable to keep the hole line true in the straight portion of the well 20 as indicated by the numeral 59 by counteracting the forces which cause drift or walk of the drill bit thereby resulting in the hole being drilled off line.
This is more Clearly seen in FIG. 2. For example it may be desirable to drill well 20 in a straight line in the direction indicated `by arrow 60. However, it has been found that if the bit is rotated as in conventional drilling the bit will tend to walk and thus cause the hole to drift as indicated by arrow 61. In FIG. 2 it can be seen that the `bit is being rotated in a right-hand direction and if nothing is done to counteract the forces acting on the bit it will walk in a right-hand direction causing the well to deviate off the desired line 60 as indicated by arrow 61.
Again referring t-o FIG. l the stabilizing member of the present invention is indi-cated generally by the numeral 64. The stabilizing member acts to counteract the forces tending to cause drift of the bit. The size and the exact position of the stabilizing member 64 with respect to the bit 23 may of course vary depending on the conditions existing in each well. However, the stabilizing member is connected above bit 23 and is provided with 3 means for causing it to rotate in a direction opposite to the direction of rotation of the bit 23.
In FIGS. 3 and 4 the preferred embodiment of apparatus of the present invention is shown. A rotary bit indicated generally by the numeral 23 'has roller cones 1t) and 11 useful to breakaway a drilling face. let ports 12 and 13 are formedin the bitV 23 to direct drilling mud at the roller cones and at the drilling face.v The bit 23 is connected by suitable means to a tubular member such as drill collar 19. T'hek drill collar is used to connect. the bit to the drill pipe to makeup the drill string.
In accordance with the present invention a stabilizing member, indicated generally by 64, is connected on the drill string above the rotary bit 23.1 The stabilizing member acts to neutralize the forces exerted on the bit which tend to cause the bit to walk off the desired drilling line. For example a stabilizing member may be suitably formed by tubular member 70-connected about drill collar 19. The tubular member may be formed in two mirror portions and connected around the drill collar 19 by suitable means such as .welding. The tubular mem- V, ber 70 is rotatably mountedk around the drill bit for rotation about an axis formed by the longitudinal axis of the ldrill bit 23 and drill collar 19. The tubular member 70 is provided with stabilizing vanes 71. The vanes 71 Y f actto increase the stabilizing effect of the stabilizing member 70.
A suitable means forrotatably mounting the tubular member 70"aroundthe drill stringincludes a pair of bal bearing means 73 and 74.y These ball bearing means are fir'edlyl connected to the drill stem by suitable means escapes from the annular space 84 between these two members through the spaces provided by spacers 76 in the ball bearing means. This mud joins with additional mud ilowing up the annulus of the well to assist in removing cuttings.
The rate of mud ilow through mud ports 83 and the angle of the vanes 4in a large measure determine the rotational speed of the tubular member. The mud ports 83 of the drill collar 19 and the jet ports 12 and 13 of drill bit 23 can be proportioned to provide a desired rotational rate for the tubular member. It is also in accordance with the invention to vary or adjust the sizes of the various mud ports by putting inserts 'in them to change or such as welding. Ball bearings75 having spacers 76 are captured in the, races 73 and 74 for Vrotation therein. Races 77 and 78 are formed inside tubular member 70. The races y77 and 78` are yformed to mate with' the ball bearing means 73 and 74. This form of mounting-allows tubular member 70 to rotate about'an axis whichY isalso the center line of the drill bit 23 and the drill collar 19.v
^ Means are provided to rotatesthe stabilizing member 64 in a direction opposite to the direction of rotation of the drilly bit23. Thus if the drill bit in FIG. 3 were to f be rotatedin a clockwiseor right-hand direction then the stabilizer member 64 would be rotated lin a counterclocltwisefor left-hand direction.' The effect. of counterrotat- Ving the stabilizing member 64 `is to help overcome the forcesY which tend to cause bit walk'.Y Most rotary drilling, is done byrotating the `bit in. a right-hand direction at from 100 to k300 revolutions per minute. v, The turbine stabilizer .member 64 rotates in the Iopposite direction.
'The optimum rotational speed of the rotating stabilizer 64V f will depend on a number of factors such as the'length of the stabilizer, the type and consistency of the drilled formations, and the ,type of bit used, etc. be said that the stabilizer should be rotated at least 1A the rotational speed of the Vbit to achieve satisfactory results.` It is preferred to have the rotational rate of the stabilizer approach and in some cases exceed the rotational rate of the bit. Thus from 100 tol 300y revolutions per minute with respect to the drill bit is the preferred rotational rate of the stabilizer.
T hemeans for rotating the tubular member 70 include' helical mud vanes 80 and 81 formed on the inner surface of theY tubular member 70. Entry port means 83 are formed in the drill collar 19 to divert a portion of the drilling mud out of the drill string into annular space 84 between the tubular member 70 :and the drill string. The
However it can vary the rotational speed. The additional power requirements to drive the stabilizing member 64 in a counterrotational direction is more than made up for by the reduction in drilling time heretofore necessary to correct hole deviation.
Although only the preferred embodiment of apparatus has been described, the invention is not to be so limited only to that embodiment. It is intended that the limits of vthe invention be dened by the scope of the appended claims.
1. Apparatus for drilling a well comprising `a drill bit, pipe means for rotatingl said drill bit, a tubular member, means for rotatably mounting said tubular member around said pipe means so that the longitudinal axis of said tubular member is parallel to the longitudinal axis of said pipe means to form an annular chamber between the out-l side of said pipe means and the inside of said tubular member7 mud vane means formed on the inside wall of said tubular member responsive to mud ow to rotate said ytubular member in a directions-opposite to the normal rotational direction of said drill bit, portmeans in said pipe means for diverting a portion Iof the drilling mud passing therethrough to said annular chamber to cooperate with said mud vane means to rotate said tubular member and passageway means in said tubular member downstream of said mud vane means'for returning drilling mud 'from said annular chamber directly to the well. Y 2. Apparatus for drilling a Well comprising a drill bit,
pipeA means for rotating said drill bit, a tubular member, means for rotatably. mounting said tubular member around said pipey means so that the longitudinal axis yof said tubular member is parallel to the longitudinal axis of said pipe means to form an annular chamber between the outside of said pipe means and the inside of said tubular member, mud vane means formed on the inside wall of saidn sageway means formed at each end of said tubular memmud vanes 80 and 81 4are .formed in a manner to cooperate v to rotate the tubular member in the desired direction. Thus in the embodiment illustrated in FIGS. 3 and 4 the vanes are helically formed in opposite directions above and below mud entry ports 83. Thus drilling mud under Vpressure enters the annular space 84 between the interior of the tubular member 70 and the exterior of the drill collar 19 and acts on vanes 80 and 81 to turn the tubular member 70 in a counterclockwise direction. The mud ber downstream of said mud vane means for returning drilling mud yfrom said annular chamber directly to the well.
3. Apparatus for drilling a well comprising a drill bit,
pipe means for rotating said drill bit, a drill collar conbular member for rotatably mounting said tubular member around said drill collar so that the longitudinal axis of said tubular member is parallel to the longitudinal axis of said pipe means to form an annular chamber between the outside of said drill collar and the inside of said tubular member, mud vane means formed on the inside wall of said tubular member responsive to mud flow to rotate said tubular member in a direction opposite to the normal rotational direction of said drill bit, port means in said drill collar intermediate the ends of said tubular member for diverting a portion of the drilling mud passing therethrough to said annular chamber to cooperate with said mud vane means to rotate said tubular member and passageway means through said bearing means of said tubular member downstream of said mud vane means for returning drilling mud from said annular chamber directly to the well.
4. Apparatus as in claim 3 further characterized in that the mud vane means are formed vof two opposing helical vanes cooperating with mud tlow t-o rotate the tubular member in a direction opposite the normal rotation-a1 direction of the drill bit.
5. Apparatus as in claim 3 further characterized in that the tubular member is provided with external ns which G are rotatable therewith to assist in stabilizing the drill string.
References Cited by the Examiner UNITED STATES PATENTS 2,591,488 4/1952 Yost 175-107 X 2,635,852 4/1953 Snyder 175-107 X 2,714,500 8/1955 Snyder 175-323 3,109,501 11/1963 Pugh 175--325 10 CHARLES E, OCONNELL, Primary Examiner.
JACOB L. NACKENOFF, Examiner.
I. A. CALVERT, Assistant Examiner.