US 3260318 A
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Description (OCR text may contain errors)
July 12, 1966 w. J. NELSON ETAL 3,250,318
WELL DRILLING APPARATUS Filed NOV. l2, 1.963
United States Patent O 3,260,318 WELL DRILLING APPARATUS William J. Neilson, Whittier, Erskine P. Garrison, Long Beach, and Gayle D. Smith, Norwalk, Calif., assignors to Smith Industries International, Inc., Compton, Calif., a corporation of California Filed Nov. 12, 1963, Ser. No. 322,596 1 Claim. (Cl. 175-75) This invention relates to improvements in well drilling apparatus.
Heretofore it has Abeen recognized that a number of advantages can be gained in drilling Wells by employing a stationary drill pipe or drill string which has attached at its lower end a down hole motor the rotor of which is connected to and rotates a rotary bit. In such an apparatus -a iiuid, usually a relatively incompressible liquid, is .forced down the stationary drill pipe or drill string and on passing through the fluid-operated motor causes the rotor thereof to rotate the drilling bit. The drill string is held or suspended in such a manner that it does not rotate and therefore may be regarded as being stationary. However, it is lowered in the Well as drilling proceeds.
The forces required to rotate the rotary bit at the tbottom of the string yare such that in the usual situation the fluid-operated motor must be quite lengthy. An apparatus of lthis general character is very advantageous in directional drilling in which case the practice heretofore has been to position a bent sub between the top of the fluid-operated motor and the `axis of rotation of the bit to the axis of the dril-l pipe. However, due to the length of the motor required and other structure connecting the rotor of the motor to the bit, the spacing of the bent sub from the bit is excessive. Frequently this distance amounts .to approximately 22 feet or frnore which is objectionable due to the fact that it is difficult to position and to maintain the orientation of the bit in relation to the axis of the drill pipe. These objections in directional drilling can be largely overcome if the bent sub could be located closer tothe bit.
The preferred type of Huid-operated. motor which we employ is a Moyn-o pump which when it has circulation iluid forced therethrough functions as a fluid-operated lmotor. The rotor of such -a pump has its lower end gyrating about the axis of its stator so that some form of universal joint or flexible connection must be employed in establishing and maintaining a driving connection 'between the rotor and the bit which rotates about a stationary axis. As ia clearance must exist between this universal joint or flexible connection and the walls of the surrounding housing to accommodate the flexibility of movement, we take advantage of this by bending the surrounding housing for directional drilling. In this manner, by angularly relating the axis of rotation of the bit to not only the axis of the drill string but also the axis of the Huid-operated motor attached thereto, we in effect locate the bent sub much closer to the bit than in the situation where the bent sub is located between the top of the fluid-operated motor and the drill string. Control of the bit and its orientation are consequently more easily obtained and maintained.
With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:
FIGURE l is a view in side elevation of the apparatus embodying the present invention, the same Ibeing shown in a well being drilled thereby.
FIG. 2 is a partial view in vertical section.
Referring to the accompanying drawings wherein similar reference characters designate similar parts throughout, the apparatus embodying the present invention con- 3,260,318 Patented July 12, 1966 sists of a drill pipe or drill string 10 which is stationary in the sense that it does not rotate as is the case with conventional drill pipe in a conventional rotary well drilling apparatus. This drill string leads to the top of a fluidoperated motor generally indicated at 12 consisting generally -of a stator 13 within which there is rotatable or gyratable a rotor 14. The fluid-operated motor which we employ is of the positive displacement type and preferably consists of a Moyno pump which, on having fluid such as well drilling fluid forced therethrough from the drill pipe 10, will cause the rotor 14 to rotate or gyrate with su'licient power to rotate the well drilling bit. The well drilling bit is illustrated at 15 and may be of any preferred or conventional design. This bit is rigidly connected to a rotary shaft or mandrel 16 rotatable within a bearing 17 in an outer -housing or drill collar 18. Suitable thrust bearings indicated at 19 and 19A may be employed as indicated to carry the various thrust loads that may be involved. The upper end of the shaft or mandrel 16 is provided with ports 21 through which liquid that is discharged through the stator 13 to drive the rotor 14 may enter the hollow mandrel or shaft 16 and on passing therethrough be discharged at the -bit for the purpose of lubricating t-he cutters thereof and flushing out well cuttings.
As Ithe lower end of the rotor 14 of the Huid-operated motor moves through a gyratory or elliptical path and the mandrel 16 to which the bit is connected rotates about an axis that is stationary with respect to the surrounding housing 18, some form of universal joint or flexible connection rnust be employed between the rotor 14 and the shaft 16. This is shown as consisting of upper and lower universal joints 20 and 20A, but other forms of flexible connections can be used in lieu thereof.
We take advantage of the fact that a universal joint or flexible connection must :be present between the rotor 14 and the mandrel or shaft 16 and that a clearance space 25 must exist therearound, to locate the bent sub at this point rather than at the top of the fluid-operated motor 12. In other words, where the apparatus is to be used for directional drilling the housing 26 is so shaped or designed that its .top pin 27 and box 28 are disaligned or are angularly related to each other. The fact that the housing 26 is thus in effect bent between its ends does not interfere with the universality or the flexibility of the flexible joint that connects the rotor 14 to the mandrel 16. With this arrangement the location of the bend in the drilling apparatus can be quite close Ito the Ibit 15 so that in setting the direction of drilling of the bit by turning the drill pipe 10, t-he direction can be accurately oriented. Also the proximity of the bend in housing 26 to the bit 15 facilitates the direction being maintained without a tendency of the `bit to Wander. FIG. 1 illustrates a situation wherein by reason of the angular relationship between the top and bottom of the housing 26 the axis of the -bit 15 is angularly related to the axis of the drill pipe 10.
From the above described construction it will be appreciated that as the bent sub or bent housing is located between the fluid operated motor and the Ibit rather than above the fluid-operated motor, greater control is obtainable over the direction of drilling of the bit 15. Location of the bend at this point does not interfere in any manner with the driving connection between the rot-or of the motor and the rbit. As a clearance must exist between the connection and the Walls of the surrounding housing to accommodate the universality of movement, lthis necessary clearance is taken advantage of to locate the bend at this point which is relatively close to the bit. While lthe invention has been described in connection with a down hole motor that is operated by lluid forced down the drill string, it will be readily appreciated that it is not restricted thereto but may be used with other forms of down hole motor which have exible driving connections between the rotor thereof and the bit.
Various changes may 'be made in the details of the construction without departing from the spirit and scope of the invention as defined by the appended claim.
Well drilling apparatus including a straight pipe assembly constituting a drill string, a down hole motor comprising a housing, rotor and a stator in axial alignment with the straight pipe assembly, a rotary bit below the motor including a bearing support therefor, a rigid bent pipe section closely connecting said. motor housing to said bit bearing support, and a flexible driving connection between the rotor of the motor and the bit such that the l axis of rotation of the bit is disposed at an angle to the axis of rotation of said motor.
References Cited by the Examiner UNITED STATES PATENTS 2,500,267 3/1950 Zublin 175-107 X 2,896,913 7/1959 Holmes et al. 175-75 2,898,087 8/1959 Clark 175-107 X FOREIGN PATENTS 657,749 1/ 1929 France. 1,247,454 10/ 1960 France.
CHARLES E. OCONNELL, Primary Examiner.
R. E. FAVREAU, Assistant Examiner.