US2080804A - Well drilling control system - Google Patents

Description

y 18, 1937- J. E. BRANTLY 2,080,804

WELL DRILLING CONTROL SYSTEM Filed April 30, 1935 3 Sheets-Sheet l 1720622/5)". .Tofin. E. Bran/7y May 18, 1937.

J. E. BRANTLY WELL DRILLING CONTROL SYSTEM 3 SheetsSheet 3 Filed April 30, 1955 Patented May 18, 1937 UNITED STATES PATENT OFFICE WELL DRILLING ooN'moL SYSTEM John E. Brantly, Avenal, Calif. Application April 30, 1935, Serial No. 10,011

15 Claims.

This invention relates generally to well drilling control systems of the type operating to regulate the bit feed into the formation being drilled, or to control the feed in accordance with the weight on the bit, and has for its principal object to provide a drilling control system whereby the bit may be fed or lowered at a substantially more uniform rate and under a much smoother acting control, than has heretofore been possible with known types of drilling control systems.

Several methods have in the past been proposed and used with varying degrees of success, that aim generally at the idea of controlling the rate of drilling or rate of bit feed in accordance vwith variations in the weight on the bit, by decreasing or increasing the rate of feed as the weight on the bit correspondingly increases or decreases, with a resultant approximation of a.

uniform pressure on the bit at all times and regardless of variations in the hardness of the formation. In some cases these systems have been made to operate automatically; the bit feeding mechanism responding-automatically to variations in the bit pressure.

In all instances however, these prior methods have involved a common and characteristic principle, the departure from which by the present invention is primarily responsible for its superiority. That principle, briefly, consists in placing a drilling pressure on the bit by supporting or suspending a portion only of the entire weight of the drill string, and utilizing the unsupported weight to apply pressure to the bit to force it into the formation. As harderor softer formations are encountered, greater or lesser portions of drill string load have been taken from the bit, but always, during drilling, a portion of the weight of the drill string will remain unsupported except by the bit. It will readily be seen therefore that in varying the rate of drilling or the pressure on the bit, the practice has been to control and vary the unsupported part of the total weight of the drill string.

Experience has shown that while theoretically it is possible to maintain that control, in actual practice it has not been possible to control the rate of feed or pressure on the bit within the close limits most to be desired, or to a degree where practically absolute uniformity in either of these conditions can be maintained. By the present invention I am able to achieve 'such uniformity, primarily as a result of the departure from the common principle of former methods, as discussed in the foregoing.

The novel and characteristically different mode of operation employed in the present system consists in the method of controlling the bit feed by first suspending the pipe string by a force or means suflicient to support the entire weight thereof, as distinguished from a portion only, 5

and lowering the pipe string to feed the bit during drilling by partially overcoming that force or means, but while maintaining it, by a second independent force. Thus during drilling there is always a force being applied that is sufiicient to support substantially the entire drill string load, but which is constantly being overcome by an independent force. In contrast to prior methods wherein the element of control comes about by varying the unsupported load on the bit, I con- 5 trol the rate of bit feed or the pressure on the bit by controllably varying the described independent overcoming force. The result is that by virtue of the presence of the two forces, one acting to support the entire drill string, and the other to partially overcome that force, I am able to obtain a smoothness of feed and sensitivity of control that heretofore could not be even closely approximated. As will hereinafter appear, the

present method lends itself particularly adaptably to automatic control to maintain an accurately uniform pressure on the bit, although this feature is additive and need not necessarily be employed since the system is fully responsive to manual control.

The invention embodies various additional features and objects, and includes a novel and improved apparatus for performing the operations described above. All these however will be further and completely explained in the description 3 to follow, and throughout which reference is made to the accompanying drawings, in which:

Fig. 1 is a general view; diagrammatic in parts, showing a typical well drilling and control system embodying the invention; 1

Fig. "2 is a plan view of the draw works and drilling control apparatus shown in Fig. 1;

Fig. 3 is an enlarged view in the aspect of line 3-3 of Fig. 2 showing the drill string supporting brake in side elevation;

Fig. 4 is a partly sectional view illustrating the variational and hydraulic type brake;

Fig. 5 is a fragmentary plan illustrating a sec tional variational form of brake, in this instance of an electric or motor generator type;

Fig. 6 is a line diagram showing the motor circuit and control switches;

Fig. 'l is a view, partly in section, showing a valve controlled tube used in conjunction with a hydraulic type brake: and

Fig 8 is a plan view of the rheostat control of Fig.

Referring first to Fig. l, numeral l9 indicates the usual derrick having a floor or platform II which supports the rotary table l2, the latter operating to rotate the drill pipe string i3 and bit l4 via the usual square-section kelly l5 extending through the rotary table. The drill string is supported by cable It trained over sheave wheel lid on crown block l1, and around the travelling block l8. The latter is connected to the usual swivel l9 attached to the upper end of kelly I5, by way of the swivel bail 2|l, hook 2| and ball 22 of a weight indicator 23, the purpose of which will hereinafter appear. Circulating fluid is discharged down through the kelly and drill string from the ordinary pipe or hose 24 connected to swivel l9. The drill pipe supporting cable I5 is wound around a winding drum 25 which rotates to let off cable during lowering of the pipe string, or, reversely, to take up the cable for the purpose of pulling the drill string from the well. The usual type of manually operated brake 26 applied to drum 25, preferably is used tov lower the drill string in the well to drilling depth, but thereafter, during normal drilling operations, this brake will be released and remain out of operation. In other words, His intended solely as a pipe lowering brake.

As best illustrated in Fig. 2, the draw works and drilling control apparatus comprise a shaft 21 journaled in bearings 28 and driven from a suitable power source, such as an engine or motor 29, by way of chain 39 passing around sprockets 3| and 32 on shaft 21 and the motor shaft, respectively. Rotary table I2 is driven from shaft 21 by way of sprockets 33 and 34, chain 35, and shaft 35 carrying a bevel gear 31 meshing with the rotary table ring gear l2a. The

rotary table drive may be disconnected by manually operating clutch 38 to release shaft 21 from driving connection with sprocket 33. Winding drum 25 is mounted on a shaft 39 journaled in bearings 40, and-may be driven from motor 29 by way of chain 4| carried on sprockets 42 and 43 on shafts 21 and 39, respectively, the winding drum however being disconnectible from motor 29 by means of a manually operated clutch 44 which, when released, leaves sprocket 43 floating on the drum shaft. It will be unnecessary to refer further to the driving connections between motor 29 and the winding drum, other than to state that ordinarily the drum will be driven by motor 29 only for the purpose of pulling the pipe string from the well. As will later appear, the drilling control apparatus also operates to elevate the pipe string, although at a slower rate due to the particular gear system employed, so that a separate hoisting drive for the winding drum is desirable in order to save time in pulling the pipe string.

Operating in conjunction with the draw works mechanism described thus far, is a drilling control apparatus which, as previously observed, serves to feed the bit into the formation at a uniform, even rate as a result of the adoption of a novel principle in the application of forces governing the lowering of the drill string. Broadly speaking, the drilling control system may be regarded as acting to impose sufficient force resisting rotation of winding drum 25 in a cable releasing direction, as to overcome the tendency of the cable tension imposed by the en tire weight of the drill string, to rotate the drum in that direction; or in other words, to impose sumcient resistance to drum rotation as to support substantially the entire, weight of the drill string. Then in conjunction with this force acting to resist rotation of the winding drum, I employ a second, controllably variable force which partially overcomes the drum rotation resisting the bit. Provision is made whereby this force may be controllably varied to increase or decrease the rate at which the bit is fed into the formation and, if desired, to controllably vary the drilling pressure on the bit.

While it is realized that the two forces just referred to may be applied directly to the winding drum 25, I prefer to apply the control forces indirectly through a speed increasing mechanism of the character later described, due to the fact that at normal drilling rates, drum 25 rotates so slowly in letting ofi cable as to render it diflicult, if not impossible, to obtain the desired precision and smoothness of operation in the drilling control if the said forces were to be applied directly.to the drum. Accordingly, I apply the forces to a rotating element operated in accordance with the rotation of the winding drum 25, but at a substantially greater speed, and as a result, I am able to obtain much greater smoothness and sensitiveness of control than would be possible were it attempted to apply the forces directly to the slow moving winding drum.

A second sprocket 45 on the winding drum shaft 39 is connected by chain 41 with sprocket 49 carried on the low speed shaft 49 of a speed increasing or multiplying unit 50. The latter is illustrated diagrammatically only, since speed increasers operating to multiply, in a high speed driven shaft, the rotative speed of a low speed driving shaft, or vice versa as regards the driving and driven shafts, are commonly known and require no detailed explanation or illustration.

In this case shaft 49 is operatively connected by the speed increasing mechanism with a shaft 5|, the latter rotating at a substantially greater speed than shaft 49. Winding drum shaft 39 and the speed increasing mechanism 50 may be operatively disconnected by manually disengaging the clutch 52. One end of the speed increaser shaft 5| carries a sprocket 5|a which is driven by a suitable power source, preferably a,

reversible and variable speed motor 53, via chain 54 and sprocket 55 on the motor shaft.

Broadly speaking, any suitable means may be applied to or connected with high speed shaft 5| of the speed increaser, that will impose sufllcient resistance to rotation of the shaft to hold winding drum 25 against rotation under the full load of the drill string. As a typical means whereby such rotation resisting force may be applied to shaft 5|, I show in Fig. 3 a suitable friction brake 51 illustrated conventionally as comprising a drum 58 keyed to shaft 5|, and a pair of friction bands 59 and 50 operated by lever 6| and linkage 62 to apply a braking force to drum 59 and the shaft. A tension spring 63 is connected to the handle, and the latter maybe held in fixed position to apply any desired braking force to the drum, by engagement with ratchet teeth 54 on post 55.

In Fig. 4 I show a variational mechanism in In this instance the shaft is connected to a pump 86, which may be of any suitable type, having an inlet 6! connecting with line 58, and an outlet 59 discharging into passage 10 of a multiple valve device 1|. Passage I0 is communicable with discharge passages 12 and 13 by way of separate passages 14, 15, I5 and 11, the flow of high pressure fluid through these passages from passage 70 being controlled by valves I8, 19, 89 and 8|, of progressively increasing size in the order designated. Each of the valves is seated by a compression spring 82, the thrust of which, and

therefore the resistance to opening of its valve, may be adjusted by nut 83 engaging a washer 86 against which the upper end of the spring bears. The fluid is discharged from passage 13 into a supply chamber 85 from which pump 56 takes suction through line 68.

When under the full load of the drill string, winding drum tends to rotate shaft 5|, via

-the speed increaser 59, in such direction as to cause pump 66 to discharge fluid into passage i8. Valves I8 to 8|, however, will be set to remain closed under the fluid pressure in passage at suitable predetermined increments pump disv 40v 10, thereby imposing a back pressure holding the pump rotor (not shown) and shaft 5| against rotation. The valves thus impose a resistance to fluid flow suflicient to hold shaft 5| and winding drum 25 against rotation with cable I 6 under the full load of the drill string l3.

The pipe string supporting resistance presented by valves 18 to BI" is overcome by driving shaft 5| and pump 56 from motor 53 to increase the discharge pressure in passage 18 to the point where one or moreof the valves will become unseated to allow fluid circulation and rotation of shaft 5| of the winding drum at a controlled rate. The valves will be set to open successively charge pressure; valve 78 opening first, and then valves 19, 98 and 8| as the pump discharge pressure increases in response to increases in the In the following, reference will be made only to brake 51, however with the understanding that any of the described types of brakes may be used interchangeably.

In the operation of the system, starting with the lowering of the pipe string into the well, and with clutches 38, 44 and 52 disengaged, the pipe string will be lowered in the usual manner under control of the winding drum brake 25 to substantially drilling depth. Clutch 38 is then engaged to transmit the drive from motor 29 to the rotary table l2, and clutch 52 thrown in and brake 51 adjusted and set to hold shaft 5| against rotation by the weight of the drill string transmitted through. winding drum 25, chain 4'! and the speed increaser 50. In this condition, the entire drill string will be suspended by virtue of the rotation resisting force applied by brake 51 to shaft 5|. Motor '53 is now started into opera that resistance proportionate to the speed of .lt operation ofthe motor, modifi y the resist ance of the formation to penetration byv the bit. As the motor'speed is increased or decreased, the rate of bit feed increases or decreases accordingly. Always, however, there is maintained bythe brake 51 a force suflicient to indirectly support the entire drill string, but this force is constantly being partially overcome by the force 5 for this purpose I have provided, in conjunction with the described mechanism, a'control whereby the operating speed of motor 53 is automatically regulated in accordance with variations in the pressure on the bit. A suitable weight indicator 23, which may be one of a number of types in common use, is shown to be connected into the drill string suspension, for example between the travelling block l8 and the hook 2|, so that the weight of the drill string is transmitted through the indicator. Using a weight indicator of the fluid pressure type, the regulator 23 may be connected via pressure hose with a suitable meter 9| having an indicator arm 92 actuated in response to variations in the fluid pressure in hose 90 and, accordingly, in accordance with variations in the suspended weight of the drill string. Arm 92 controls the variable resistance 93 placed in the motor circuit 94 to which current is supplied from power lines 95. Y

The motor circuit is controlled for drilling under automatic or'manual regulation, from a switch box 95 which may be placed at any convenient location. As shown in Fig. 6, the motor circuit control comprises a double-throw switch 91 which when brought into contact with poles 98, places the variable resistance 93 in the motor circuit for drilling under automatic control. previously observed, arm. 92 moves in response to variations of pressure on the bit, to control the operating speed of motor 53. As the pressure on the bit increases above normal, arm 92 moves to increase the resistance in. the motor circuit and proportionately decrease the motor speed, and consequently the rate of bit feed, until normal drilling pressure on the bit has been restored.

Conversely, the control operates automatically to increase the motor speed and rate of bit feed when the pressure on the bit falls below normal.-

- In case it is desired to control the rate of drilling by manual regulation, switch 9'! is thrown into contact with p'oles 89 to bring the manually variable resistance I08 into the motor circuit. By manually controlling the resistance -lllll, the motor speed maybe increased or decreased, as desired. If for any reason it becomes desirable to elevate the drill string by motor 53, as for example for the purpose of drilling or reaming upwardly, rotation of the motor may be reversed by. switch |9| acting to reverse the motor field. Switch |0| of course operates to reverse the-motor operation whether the system be under automatic control with switch 91 in contact with poles 98, or under manual control from the variable resistance I80.

In Figs. 7 and 8 I have illustrated a valve mechanism adapted to be installed in the discharge line of a hydraulictype brake, and operated to vary the braking force or resistance of the hydraulic brake. The valve operatingmechanism comprises means whereby movement of the valve is synchronized with a rheostat control for the motor 53, so that the valve is caused to open from fully closed position, when the motor circuit is open, progressively to fully open position as the' rheostat control comes into operation the motor reaches full speed.

As illustrated in Fig. "I, the valve proper, generally indicated at I02, may be installed in the discharge line 69 of pump 06, see Fig. 4, and, it may be observed, this valvemay be used either in lieu of or in addition to the automatic valve control II which I have previously described. The use of both the manually operated valve I02 and the automatic valve control 'II would have an advantage however in that the former provides an additional safety factor against failure of the valves in the mechanism II to properly function. The valve device I02 comprises a body I03 having inlet and outlet passages I04 and I05,

and a valve I06 having a swivel connection at I'I with stem I08 threaded at I09 throughthe cap portion I I0 of the body. Fluid leakage along the valve stem is prevented by a suitable stufllng box, as indicated at III.

The valve I06 is opened and closed by rotation of stem I08, the latter in turn -being actuated from manually rotated shaft II2 of the rheostat motor control H3. Shaft II2 drives the valve stem I08 through a speed increasing gear train I I4 comprising gear H carried on shaft I I2, and gears H6 and II! keyed to shaft II8, gear II'I meshing with gear H9 on the upper end of the. valve stem. The gear ratio of the speed increaser I Il may be selected so as to give shaft I I2 and valve stem I08 a rotation ratio of around 1 to 6, so that for a half turn of the motor controlshaft, the valve stem will make three complete turns or revolutions, moving the valve from closed to wide open position.

The motor control, generally indicated at I20, comprises a rheostat having a variable resistance I2I in serieswlth one of the power lines 05 leading to the motor 53, the rheostat being thrown into the circuit by rotating arm I22 from the dotted position l22a into contact with the resistance I2I, arm I22 being carried on-shaft H2 and the latter rotated by a suitable hand control I23. When arm I22a is in the dotted line position illustrated, with the motor circuit open and'the motor not in operation, valve I00 is then in closed position. As the motor is brought into operation and its speed progressively increased by rotating the rheostat arm I22 in a clockwise direction as viewed in Fig. 8, valve I00 is progressively raised a distance proportionate to the speed of operation of the motor. When the motor is operated at maximum speed the valve is wide open.

It will be understood of course that when the rheostat motor control I is being used, then the previously described motor control operated in accordance with the weight on the bit, will not be employed. If desired, however, the two controls may be connected into the motor circuit and used selectively or alternately, as desired.

I claim:

1. In a rotary well drilling employing a bit I carried by a rotatably driven pipe string whose length and weight are increased as drilling progresses, and means rotatable to lower the pipe' string; the method of smoothly feeding the bit that includes. suspending the pipe string by continuously applying to said rotatable means a controllably variable rotation resisting force sufficient to'support substantially the entire weight of any length thereof during drilling, and lowering the pipe string and continuously exerting downward pressure on the bit to drill the formation by partially overcoming said force by a second force independent of the pipe suspending and rotating forces, while at the same time maintaining the first mentioned force.

2. In rotary well drilling employing a bit carried by a rotatably driven pipe string whose length and weight are increased as drilling progresses, and means rotatable to lower the pipe string: the method of smoothly feeding the bit that includes, suspending the pipe string by continuously applying to said rotatable means a controllably variable rotation resisting force sufficient to suspend substantially the entire weight of any length thereof during drilling, lowering the pipe string and continuously exerting downward pressure on the bit to drill the formation by partially overcoming said force by a second force independent of the pipe suspending and rotating forces, and controllably varying said second force while at the same time maintaining the first mentioned force.

3. In rotary well drilling employing a bit carried by a rotatably driven pipe string lowered in the well by an attached suspension means, and

' means rotatable to release said suspension 'means,

the length and weight of said pipe string increasing as drilling progresses; the method of smoothly feeding the bit that includes, continuously applying to said rotatable means a controllably variable rotation resisting force suillcient to suspend substantially the entire weight of any length of the pipe string during drilling, and lowering the pipe string and continuously exerting downward pressure on the bit to drill the for-. mation by partially overcoming said force by applying to said means a rotation producing force independent of the pipe suspending and rotating forces, while at the same time maintaining the first mentioned force.

4. In rotary well drilling employing a bit carried by a rotatably driven pipe string whose length and weight are increased as drilling progresses, and means rotatable to lower the pipe string; the method of smoothly feeding the bit that includes, suspending the pipe string by continuously applying to said rotatable means a controllably variablerotation resisting force sufllcient to suspend substantially the entire weight of any length thereof during drilling, lowering the pipe string and continuously exerting downward pressure on the bit to drill the formation by partially overcoming said force by a second force independent of the pipe suspending and rotating forces, while at the same time maintaining the first mentioned force, and continuously applying said second mentioned force to advance the bit through-the formation.

5. In rotary well drilling employing a bit carried by a rotatably driven pipe string lowered suspending and rotating forces, while at the same time maintaining the first mentioned force, and continuously applying and controllably varying said second mentioned force to advance the bit through the formation.

6. In rotary well drilling employing a bit carried by a rotatably driven pipe stringlowered in the well by a cable released from a rotatable winding drum, the length and weight of said pipe string increasing as drilling progresses; the method of smoothly feeding the bit that includes, restraining rotation of said winding drum by applying thereto a continuous and controllably variable force sumcient to support substantially the entire weight of any length of the pipe string from the drum by way of said cable, and lowering the pipe string and continuously exerting downward pressure on the bit to drill the formation by partially overcoming said force by a second independent force, while at the same time maintaining the first mentioned force.

7. In rotary well drilling employing a bit carried by a rotatably driven pipe string lowered in the well by a cable released from a rotatable winding drum, the length and weightof said pipe string increasing as drilling progresses; the methodof smoothly feeding the bit that includes, restraining rotation of said winding drum by applying thereto a continuous and controllably variable force sufficient to support substantially the entire weight of any length of the pipe string from the drum by way of said cable, lowering the pipe string and continuously exerting downward pressure on the bit to drill the formation J by partially overcoming said force by a second independent force, while at the same time maintaining the first mentioned force, and continuously applying and controllably varying the second mentioned force to advance the bit through the formation.

8. In rotary well drilling employing a bit carried by a rotatably driven pipe string whose length and weight are increased as drilling progresses, and means rotatable to lower the pipe string; the method that includes, suspending the pipe string by applying to said rotatable means a continuous and controllably variable rotation resisting force suflicient to suspend substantially the entire weight of any length thereof during drilling, lowering the pipe string and continuously exerting downward pressure on the bit to drill the formation by partially overcoming said force by a second independent and continuously applied force, while at the same time maintaining the first mentioned force, and automatically varying the second mentioned force in accordance with variations in the weight on said bit.

9. In rotary well drilling employing a bit carried by a rotatably driven pipe string lowered in the well by an attached suspension means, and means rotatable to release said suspension means, the length and weight of said pipe string increasing as drilling progresses; the method that includes, continuously applying to said rotatable means a controllably variable rotation resisting force sumcient to suspend substantially the entire weight of any length of the pipe string during drilling, lowering the pipe string and continuously exerting downward pressure on the bit to drill the formation by partially overcoming said force by applying to said means a rotation producing force independent of the pipe suspending and rotating forces while at the same time maintaining the first mentioned force, and automatically varying the second mentioned force in winding drum by applying thereto a continuous and controllably variable force sufficient to support substantially the entire weight of any length of the pipe string from the drum by way of said cable, lowering the pipe string and continuously exerting downward pressure on the bit to drill the formation by partially overcoming said force by a second independent and continuously applied force, while at the same time maintaining the first mentioned force, and automatically varying the second mentioned force in accordance with variations in the weight on said bit.

11. In combination with a rotary well drilling pipe string carrying a bit, a rotatable winding drum, and adrill pipe suspension cable released from said winding drum; a speed multiplying mechanism, a shaft connected via said mechanism with said winding drum so as to rotate at substantially greater speed than the drum, a brake for applying a rotation resisting force to said shaft to restrain rotation of said winding drum, and a motor for driving said shaftand winding drum, both said brake and motor being located at the high speed side of said speed multiplying mechanism. p

12. In combination with a rotary well drilling pipe string carrying a bit, a rotatable winding drum, and a drill pipe suspension cable released from said winding drum; a speed multiplying mechanism, a shaft connected via said mechanism with said winding drum so as to rotate at substantially greater speed than the drum, means at the high speed side of said speed multiplying mechanism for continuously applying a rotation resisting force to said shaft to restrain rotation of said winding drum, and a motor connected to and driving said shaft.

13. In combination with a rotary well drilling pipe string carrying abit, a rotatable winding drum, and a drill pipe suspension cable released from said winding drum; a speed multiplying mechanism, a shaft connected via said mechanism with said winding drum so as to rotate at substantially greater speed than the drum, means continuously applying a rotation resisting force directly to said shaft to restrain rotation of said winding drum, and a motor connected to and driving said shaft, said motor operating to partially overcome the shaft rotation resisting force applied by said means.

14. In combination with a rotary well drilling pipe string carrying a bit, a rotatable winding drum, and a drill pipe suspension cable released from said winding drum; a speed multiplying mechanism, a shaft connected via said mechanism with said winding drum so as to rotate at substantially greater speed than the drum, a brake connected directly to said shaft and operable to resist rotation of the shaft and said winding drum, and a motor connected to said shaft and operable to rotate said drum.

15. In combination with a rotary, well drilling pipe string carrying a bit, a rotatable winding drum, and a drill pipe suspension cable released from said winding drum; a speed multiplying mechanism, a shaft connected via said mechanism with said winding drum so as to rotate at substantially greater speed than the drum, a brake connected directly to said shaft and resisting rotation of the shaft and said winding drum sufllciently to enable substantially the en- 5 tire weight oi! the pipe string to be supported from the drum by way of said cable, an electrically driven motor connected to said shaft and operatin: to partially overcome the shaft rotation resisting force applied by said brake, and means automatically controlling the speed of said motor in accordance with variations in the weight on said bit.

JOHN E. BRAN'ILY.

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