US3043380A

US3043380A - Means for governing fluid pump in rotary well drilling rig

Info

Publication number: US3043380A
Application number: US731930A
Authority: US
Inventors: Clark Wallace
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-04-30
Filing date: 1958-04-30
Publication date: 1962-07-10
Anticipated expiration: 1979-07-10

Description

W. CLARK July 1o, 1962 MEANS F'OR GOVERNING FLUID PUMP IN ROTARY WELL DRILLING RIG Filed April 50, 1958 2 Sheets-Shet 1 villin- INVEN TOR. WALLACE CLARK,

ATTORNEYS.

July 1o, 1962 W, CLARK 3,043,380

MEANS FOR GOVERNING FLUID PUMP IN ROTARY WELL DRILLING RIG Filed April 50, 1958 2 Sheets-Sheet 2 34 f u; i 2l INVENTOR. WALLACE CLARK,

ATTORNEYS United States Patent C) 3,043,380 MEANS FOR GOVERNING FLUID PUMP IN ROTARY WELL DRILLING RIG Wallace Clark, RR. 10, Box 409, Indianapolis, Ind. Filed Apr. 30, 1958, Ser. No. 731,930 6 Claims. (Cl. 175-26) This invention relates to well drilling and more particularly to rotary drilling rigs in which the drill bit is rotated by means of a hydraulic motor suspended within the well bore at the bottom of the hole.

In this type of rotary well drilling rig the drill motor, which is suspended within the well bore by sections of casing, tubing or drill pipe, is a hydraulic motor adapted to be driven by a fluid which is pumped through the drill pipe. Mud is the commonly used fluid. It is delivered to the casing, tubing, or drill pipe from a reservoir b-y means of a pump which is usually set to deliver the mud at a constant volume, but which volume should be advisably controlled to compensate for hydraulic slip in the drill bit motor. If the rate of low requires changing, so as to maintain the speed of rotation of the drill bit motor, or to hold the speed of the motor constant to compensate for hydraulic slip resulting from variations in its required torque, or to prevent stalling, such alteration must be done manually, if at all.

In drilling a deep well, the drill bitpasses through various strata, some of which may be very hard and dense and others of which may be soft, porous and the like, and o it is desirable to maintain the speed of the drill bit constant regardless of the particular conditions encountered or the bit may stall. For example, if the drill bit encounters hard rock, it will by nature rotate at a higher rate of speed, Whereas when the drill bit runs into a soft formation, it will dig in, reducing the rotative speed of the drill bit, assuming that the weight on the bit is constant, and the result may be a stalled or stuck bit with much time loss.

It is, therefore, a principal object of the present invention to provide a method and means for automatically maintaining constant rotative speed of the drill bit regardless of the Work required by the bit and in spite of the varying hydraulic slip, which must naturally vary with the torque required to cut the different types of formation from hard to soft.

A further object of the invention is the provision of a method and means for governing the operation of the pump which supplies fluid to the drill bit motor in accordance with the torque established in the drill pipe or drilling string by the drill bit motor.

This is accomplished by positively rotating the drill pipe at a slow constant rate of speed and by utilizing the torque of the drill pipe driving means as a reactor responsive to the torque of the drill bit motor. In this connection, it should be explained that the power or torque required to rotate the drill pipe at constant speed will be affected only by variations in the torque reaction of the drill bit. This is because the friction of the drill pipe against the drilling mud and against the walls and lining of the well is constant at a given depth, the rota- -tive speed of the drill pipe is constant, and the inertia of the drill pipe need not be taken into consideration. As will be explained more fully hereinafter, the torque reaction of the drill pipe driving means is utilized to control the operating speed of the pump supplying fluid to the drill bit motor.

Reference is now made to the accompanying drawings wherein:

FIGURE 1 is an elevational view with parts broken away showing a well drilling rig in accordance with the invention.

lee

FIGURE 2` is an enlarged fragmentary plan view with parts broken away illustrating the mounting of the drive motor in its trunnions.

FIGURE 3 is a fragmentary and diagrammatic representation of a modification.

FIGURE 4 is a schematic representation of another modification.

Referring now to FIGURE l of the drawings, I have therein illustrated an exemplary rotary drilling rig comprising a string of drill pipe 10 extending downwardly into a-well 11, the drill pipe mounting at its lowermost end a drill bit motor 12 to which a drill bit 13 is operatively connected. It will be understood that the motor will be of hydraulic character and reference is hereby made to Clark Patent 2,898,087, dated August 4, 1959 and entitled Well Drilling Apparatus and Method, wherein there is disclosed a drill bit motor and bit assembly capable of use in conjunction with the instant invention. At its upper end, the string of drill pipe is ixedly secured to a polygonalkelly which is slidably journaled in a rotary table 15 having a peripheral bevel gear 16. The kelly extends upwardly beyond the rotary table Where it is suspended, as by means of hook 17, from a derrick, a portion of which is indicated at 18. At its upper end the kelly mounts a swivel connection 19 connected to a uid supply hose 2d through which the drilling fluid is supplied to the drill pipe, it being understood that the kelly is hollow so that the fluid may flow. downwardly therethrough. In the embodiment illustrated, the fluid supply hose 20 is connected to a pump 21 having a conduit 22 for supplying fluid from a reservoir or other source of supply (not shown). The pump is adapted to be driven by a prime mover 23 which in this instance, comprises an internal combustion engine, the crank shaft of the engine being connected through suitable gearing 24l to the rotor of the pump.

In accordance with the instant invention, the table 15 is adapted to be rotated at slow speed by means of a suitable prime mover 25 which is preferably an electric motor, the motor acting to drive the table through a chain drive 26 and suitable reduction gearing, indicated generally at 27, the gearing including a bevel gear 28 meshing with the peripheral bevel gear 16 forming a part of the table.

In accordance with the invention, the motor 25 is mounted in trunnions 29 in such fashion that its stator or housing can rotate about the axis of its rotor in response to variations in its torque reaction. This may be readily accomplished in numerous ways, as by providing the motor housing with mounting rings 40a concentrically disposed with respect to rotor shaft 41, thefmounting rings 40a 4being journaled in Vtrunnions 29 by means of bearings 42. A spring 30 connected to the motor housing serves to balance the torque reaction, and an adjustable stop 30a is mounted on the motor housing, the stop contacting one of the trunnions 29 and arranged to establish the desired initial balance of the motor. The motor housing also mounts an arm 31 which is connected by linkage 3-2 to the carburetor or fuel pump 33 of the engine 23. With this arrangement, and depending upon -whether the motor housing is rotated in a clockwise or counter clockwise direction, the linkage 32 will actuate the carburetor t0 either accelerate or decelerate the engine and thereby vary the speed at which pump 21 is driven.

g In the operation of the device just described, the drill pipe 10 is rotated at a predetermined constant speed, which may -be in the neighborhood of 5 r.p.m. At the same time the fluid pump 21 will be operating to supply fluid to drive the cutter bit motor 13. With this arrangement, and with 4the motor 25 driven at a constant speed, variations in the torque reaction of the drill bit will be directly reflected in the torque reaction of the motor 25.

For example, an increase in the torque reaction of the drill bit coincident with a decrease in its speedas when a soft formation is encounteredwill cause an increase in the torque reaction of the motor 25 as it seeks to maintain a constant speed of rotation. If the motor is turning counter clockwise, as indicated by the arrow A in FIG- URE 1, the increase in torque reaction of the motor will cause its housing to rotate in a clockwise direction. This movement raises the arm SI1 and through it advances the setting of carburetor 33, thereby causing the engine 23 to accelerate and hence maintain the speed of the fluid pump 2l which otherwise would be slowing down from the greater load thereon. This in turn results in an increase in the fluid flow to the cutter bit motor 13 and hence serves to compensate for the increased resistance of the soft formation. If, on the other hand, the cutter bit encounters a hard formation, or if the bit -is off bottom or the weight of the bit lightened, its torque reaction will be decreased and, similarly, lthe torque reaction of the motor 25 will be decreased and the arm 31 will tend to move downwardly, thereby altering the setting of the carburetor 33 and reducing the speed of the engine 23. This of course reduces the power -to the pump 2l and the pressure to the cuttor bit motor 13, thereby causing the cutter bit to rotate at the desired constant speed and avoiding an excess speed. It will be understood, of course, that both the power input of the motor 25 and the tension of the spring 30 will require balancing to obtain the proper proportioning and adjustment of the parts. Simi- Alarly, the length of the governor linkage 32| must be yadjusteclfro-m time to time to assure proper speed of the drill motor at various depths, as 4the pump requirement increases with depth of drill pipe. Any conventional form of mechanical governor linkage can be used as well as hydraulic, magnetic, electrical or punched tape types.

In the embodiment illustrated in FIGURE 3 the fluid pump 21 is adapted to be driven by a variable speed electric motor 34 connected by a circuit 35 to a speed control panel 36 having an arm 37 connected by a link 3S to the arm 3l of motor 25'. As before, the housing of motor 25 is rotatably journaled in the trunnions 29 and, depending upon the torque reaction of the motor, the arm 31 will raise -or lower the arm 37 of the speed control device and thereby control the speed of the fluid pump.

In FIGURE 4, I have illustrated yet a `further modication of the invention wherein the electric motor 34 which drives the fluid pump is controlled as to its speed by means of a servo-mechanism 39, which servo-mechanism may comprise a moving iron solenoid 39a connected in series with the power input to the motor 25 and responsive to fluctuations in the power input of the motor 25 as indicated by the ammeter 49'. The power input of the motor will accurately reflect any change in the torque reaction of the motor, that is, the quantity of current consumed will vary directly with the reactive torque of the motor, and by coupling the solenoid 39a to a rheostat 3915 supplying current to the pump motor 34, the current responsive Solenoid 39a will control, the speed of the pump motor 34- which will be increased or decreased in direct relation to the torque reaction.

Further modifications may be made in the invention without departing from the spirit of it. For example while in the embodiment of FIGURE 3, I have illustrated a servo-mechanism coupled to the ammeter 40, it will be apparent that the variations of the power input could be noted by the operator and the speed of the fluid pump adjusted accordingly. As illustrated in FIGURE l, the ammeter 4t) may be conveniently mounted on the motor 25, if so desired. A similar arrangement could be provided in the embodiments of FIGURES l and 2 wherein the arm 3l connected to the motor housing could be used as a pointer movable over a scale which would indicate to the operator the proper speed for the fluid pump. Both of these expedients, however, lose the automatic feature inherent in the preferred embodiments of the invention.

Having however described by invention in certain eX- emplary embodiments, what I desire to secure and protect by Letters Patent is:

l. In rotary well drilling apparatus, a drill string, a drill bit, a fini-:l motor suspended within said drill string for rotating said drill bit, a pump for supplying fluid to said drill bit motor, means for driving said pump, an electric motor for rotating said drill string at a constant rate of speed, said electric motor having a rotor and a stator, said rotor being operatively connected to said drill string, means mounting said stator for rotation about the axis of said rotor, means resiliently biasing said stator in one direction, an arm on said stator, and linkage means connecting said arm and the means for driving said pump, sai-d last named means having a movable speed control member responsive, through said linkage means, to movement of said arm.

2. The device claimed in claim l wherein the means for driving said pump comprises an internal combustion engine, and wherein said movable speed control member comprises the carburetor thereof.

3. The device claimed in claim l wherein the means for driving said pump comprises a variable speed electric motor controlled by said movable speed control member.

4. in combination in a rotary well drilling rig, a hollow drill string, a fluid motor secured to the lowermost end of said drill string, a drill bit connected to and driven by said fluid motor, a pump operatively connected to said hollow drill string for supplying iluid through said drill string to drive said drill bit motor, means including a drive motor for slowly rotating said drill string, sensing means connected to said drive motor for sensing variations in the torque reaction of said drive motor, and means operatively connecting said sensing means and said pump and responsive -to variations in the torque reaction of said drive motor for varying the speed of said pump, said last named means acting to increase the speed of said pump as Ithe `torque reaction of said drive motor increases and cli-crease the speed of said pump as the torque reaction of said drive motor decreases.

5. The combination claimed ink claim 4 wherein said drive motor comprises an electric motor, wherein said sensing means comprises a servo-mechanism, such as a soienoid, operatively connected to the power input ofV said electric motor, said solenoid being responsive to variations in the power input yto said motor and acting to increase and decrease the speed of said pump in accordance therewith.

6. The combination claimed in claim 4 wherein said drive means comprises an electric motor having a rotor and a stator, wherein said rotor is operatively connected to said drill string, wherein said stator is rotatably mounted for movement relative to said rotor, wherein said sensing means includes spring means biasing said stator in one direction and an arm on said stator, and linkage means operatively connecting said arm to said pump, said pump including drive means having a movable speed control member responsive through said linkage means to movement of said arm.

References Cited in the file of this patent UNITED STATES PATENTS 2,314,560 Scharpenberg Mar. 23, 1943