Method and apparatus for actuating downhole devices

Abstract

To actuate downhole devices in accordance with the disclosure, fluid is pumped through the drill string at a rate that creates a preselected pressure condition in the drill string. At such preselected pressure condition, a timer is actuated that continues to run as long as the preselected pressure condition exists. If the pressure condition is maintained for a length of time sufficient for the timer to time out, the downhole device will be actuated. The device is deactuated by circulating fluid through the drill string to create a second pressure condition that actuates a timer that runs as long as the preselected pressure condition is maintained. When the timer times out, it deactivates the device. In another embodiment, the particular device to be actuated is selected by rotation of the drill string after the timer times out. It is deactuated by creating a particular flow condition until the timer times out. A third embodiment permits selection of simultaneous functions by the flow-time method and deactuation by stopping fluid circulation.

Description

This invention relates to a method of and apparatus for actuating one or more downhole devices carried by a drill string.

There is a need from time to time in rotary drilling operations to cause a downhole device carried by the drill string to do something or to stop doing something. For example, if the drill string includes a fluid motor it may be desirable from time to time to lock the rotor of the motor to the stator so the assembly attached to the rotor can be rotated by the drill string and to later unlock the rotor for continued drilling without having to pull the pipe string out of the hole. Another example is the periodic measurement of hole inclination and azimuthal direction. This is done by lowering the measuring devices to the bottom of the drill string from the surface. If these devices could be carried by the drill string and turned on and off quickly, considerable down time would be saved.

In Arps U.S. Pat. No. 2,924,432, entitled "Earth Borehole Logging System", that issued Feb. 9, 1962, a system for actuating a downhole device is disclosed. With this system, the device is actuated by cycling the pressure in the drill string between a low and a high value. Thus, the actuating apparatus is operated each time the circulation pressure fluctuates between the two values, as for example, when pumping is stopped to make a connection.

It is an object of this invention to provide a method of and apparatus for actuating one or more downhole devices carried by the pipe string that requires a particular pressure condition to exist in the pipe string for a finite period of time before the device is actuated.

It is another object of this invention to provide a method of and apparatus for deactivating a downhole device carried by a pipe string by creating a preselected pressure condition in the pipe string and maintaining this pressure condition for a finite preselected period of time whereby the device will not inadvertently be deactivated when the pressure is reduced to make a connection or raised back to normal drilling pressure conditions.

It is a further object of this invention to provide a method of and apparatus for actuating a downhole device carried by a drill string that can be used to actuate the device when desired, but that otherwise is unaffected by normal drilling operations.

It is another object of this invention to provide a method of and apparatus for actuating a selected one of a plurality of downhole devices carried by a drill string by maintaining preselected pressure conditions in the drill string for a finite preselected period of time.

These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of the specification, including the attached drawings and appended claims.

In the drawings:

FIGS. 1A and 1B are vertical sectional views through a preferred embodiment of the apparatus of this invention;

FIG. 2 is a circuit diagram showing the electrical system used in the embodiment of FIGS. 1A and 1B;

FIG. 3 is a graph of time versus flow rate or pressure;

FIG. 4 is a graph of time versus voltage;

FIGS. 5A and 5B are vertical sectional views through an alternate embodiment of the apparatus of this invention;

FIG. 6 is a vertical sectional view through another alternate embodiment of this invention;

FIG. 7 is a cross-sectional view taken along line 7--of FIG. 6; and

FIG. 8 is a cross-sectional view taken along line 8--8 of FIG. 6.

In the embodiment shown in FIGS. 1A and 1B, tubular body or housing 10 is located in pipe string 11 at the desired position, which will usually be adjacent the lower end of the string. It can be held in position in any convenient manner. Located adjacent the upper end of body 10 is orifice 12 to cause a pressure drop in fluid flowing through the orifice. Upstream of orifice 12, when fluid is pumped down the pipe string in the conventional manner, is tubular diaphragm 13. The opposite ends of the diaphragm are in sealing engagement with body 10 with the portion in between spaced from the body to form annular cavity 14.

Mounted below orifice 12 in body 10 is instrument housing 15. A plurality of electrical components are located in cavity 16 of the instrument housing, including pressure sensitive switch assemblies 17 and 18. Cavity 16 of the instrument housing is connected to annular cavity 14 above orifice 12 by passageway 19. By filling annular cavity 14 of the passageway with a liquid, such as oil, the pressure above orifice 12 will be transmitted to the upper end of cavity 16 and directed to act against pressure switch assemblies 17 and 18. These pressure sensitive switches could be of the type that are actuated by a given static pressure coming from one source, such as annular space 14. Preferably, however, the switches are actuated by the differential pressure created by the pressure drop in the fluid flowing through orifice 12. The switches then are independent of hydrostatic pressure, which will vary depending on the position of the switches in the well bore. Each assembly includes two switches connected in series. One is normally open and closes at a first preselected pressure differential. The other is normally closed and opens at a second preselected pressure differential. When the pressure differential is between the first and second pressure differentials, the switch assembly is closed and current can flow therethrough.

Therefore, instrument housing 15 has section 15a of reduced diamter located inside of cylindrical screen 21 that is surrounded by tubular diaphragm 20. The opposite ends of the diaphragm are sealed to the instrument housing with the portion in between spaced from the housing to provide annular chamber 22. With this chamber filled with a liquid, such as oil, the pressure in pipe string 11 adjacent the instrument housing is transmitted to space 16 through passageway 22a. Pressure switch assemblies 17 and 18 are arranged to sense the difference in the pressure in passageways 19 and 22a that is created by the pressure drop across orifice 12 when fluid is pumped down drill string 11. The amount of pressure drop is dependent upon the rate of flow and other factors, such as the viscosity of the fluid being pumped.

In accordance with this invention, timing means are provided that will operate while certain pressure conditions exist in the pipe string. In the embodiment shown, such timing means include R-C timing circuit 23 (enclosed by dashed line box), as shown in FIG. 2. The timing circuit is actuated when the pressure differential across orifice 12 is within the preselected range that closes pressure switch assembly 17 and connects R-C circuit 23 to battery 24. As long as the pressure differential stays within the preselected range, the battery will supply electrical energy to the timing circuit until such time as the charge on capacitor 25 has reached the point that it will actuate relay 26. The time required for this to occur is determined by the circuit components, but it should be long enough to allow the pressure differential across orifice 12 to move back and forth through the range, as occurs during normal drilling operations, without causing the circuit to time out, i.e., actuate relay 26.

The relay drops the timing circuit out and energizes solenoid 27 and stepping switch solenoid 28a. The stepping switch solenoid moves stepping switch 28 into position to actuate a downhole device. A plurality of such devices could be used with the stepping switch, with each position of the switch designed to actuate a different device.

At the same time that the downhole device is being actuated, solenoid 27 closes outlet 29a of hydraulic pump 29. This causes fluid from the pump to travel through passageway 30, down the annular space between the pump housing and cylinder 31 and through ports 32 into the bottom of the cylinder below piston 33. The fluid raises piston 33, and in doing so raises valve member 35 toward valve seat 36, which is actually the tapered downstream side of orifice 37. By narrowing the distance between valve member 35 and valve seat 36, a pressure pulse will be created in the fluid being pumped down the pipe string. The pressure pulse can be detected at the surface and provides an indication that the downhole device is now actuated.

Power is supplied to pump 29 by impeller 48. The impeller has vanes 48a that cause hub 48b to rotate when drilling fluid is pumped down the drill string. Output shaft 48c is connected to the hub and supported by piston 33. Drive shaft 34 of the pump extends into and has a splined connection with output shaft 48c. It can telescope into the output shaft as the piston moves, but is connected for rotation therewith by the splines. Thus, rotation of the impeller by the flowing drilling fluid drives pump 29.

The charge in capacitor 25 will hold relay 26 actuated long enough for the solenoid and stepper switch to so function, after which the charge will have bled down to the point that the relay will fall out. If pressure switch 17 is still closed by the pressure existing across it, R-C timing circuit 23 will be connected again to battery 24. If it is desired to simply step stepper switch 28 one step and actuate that device, then as soon as the signal of the pressure pulse reaches the surface, the pressure differential across the switch should be changed so that switch 17 will open, otherwise the cycle will repeat itself and the stepper switch will be stepped again, which could deactivate the device actuated by the first step of the switch. This would depend on the arrangement of the stepper switch. Stepping the switch twice could stop the first device actuated or not as desired. On the other hand, if the device that is to be actuated is at the third or fourth position of the switch, then by simply holding the pressure differential across switch 17 such that switch 17 remains closed, then the circuit will simply time out three or four times stepping the stepper switch three or four times, after which when the third or fourth pressure pulse reaches the surface, the operator can change the pressure conditions and open the switch.

Means are provided to stop the actuated downhole device or devices when a preselected pressure condition exists in the drill pipe. This is the function of pressure switch 18, second R-C timing circuit 38, and relay 39 of FIG. 2. A pressure drop within a preselected range is created across orifice 12. This closes switch assembly 18 connecting R-C timing circuit 38 to battery 24. When the charge has built-up on the condenser of the circuit sufficiently to actuate relay 39, erasing solenoid 40 will be actuated, releasing stepper switch 28 to be returned by springs or the like to its original position. This deactivates all devices.

The electrical components described above are supplied with power by battery 24 in this embodiment. Generator 42 supplies charging current to the battery to keep it charged. The generator is operated by vertical vibrations of the pipe string, which will be substantial if the pipe string, for example, is being employed in a drilling operation. The generator is shown schematically and includes coils 43 and 44. They are located in the magnetic field of magnets 45 so that relative movement of the coils and the magnets will induce a current in the coils that can be used to charge battery 24. In the embodiment shown, the magnets are mounted on springs 46 so that their inertia will cause them to tend to remain stationary while the pipe moves the coils thereby producing the desired relative movement of the magnetic field and the coils to induce a current. Diode 47 rectifies the induced current to provide a DC charging current to the battery.

FIG. 3 shows graphically the relationship of flow rate or pressure drop across orifice 12 versus time. FIG. 4 shows graphically the voltage build up on capacitor 25 or 38a, as the case may be, versus time. In FIG. 3, curve A shows the pressure drop across orifice 12 as the driller brings his circulation rate from zero up to normal drilling rates. In doing so, the pressure drop across the orifice will for short periods be in pressure ranges E and F, during which times pressure switch assemblies 17 and 18 will be closed. The length of time that each is closed, however, is insufficient to allow time delay circuits 23 and 38, respectively, to actuate relays 26 and 39, so nothing happens. Thus, the driller can bring his flow rate up to that of normal drilling or circulate drilling fluid for any purpose and as long as he passes through pressure ranges E and F before the timing circuits time out, the stepper switch will be unaffected. When such circulation is stopped, the pressure will drop through these ranges, of course, but again will not be in the ranges long enough to actuate the stepper switch.

Should the driller desire to step switch 28 to actuate one or more downhole devices in his drill string, he adjusts the flow rate to produce a pressure drop within pressure range E. This closes switch 17 and energizes timing circuit 23. For example, curve B of FIG. 3 illustrates such an operation. The driller brings the flow rate up from zero. He enters pressure range E, then exceeds it slightly. During the time that the pressure drop is out of the range, switch 17 will be turned off. The pressure drop then stabilizes within the range and switch assembly 17 remains closed and a charge builds up on capacitor 25.

FIG. 4 illustrates the build up of voltage on the capacitor versus time. This is shown with curve C. The square-shaped curve D is representative of the periods of time that the pressure switch 17 is closed. Thus, during the first brief period D.sub.1 that switch 17 is closed, a small amount of voltage builds up on the capacitor. Then, the switch is off again for a short period of time and some of the charge drains off. During time interval D.sub.2, voltage builds up to the point where relay 26 is actuated. As explained above, this cuts off the source of power to the timing circuit, as shown by the gap between D.sub.2 and D.sub.3, and the voltage on the capacitor begins to drain off. When solenoid 27 causes pump 29 to move valve element 35 up far enough to cause a pressure pulse, this will, of course, affect the rate of flow of fluid through the drill pipe and may cause the pressure drop across orifice 12 to drop to a point out of the pressure range E, as indicated in FIG. 3 by curve B. This is a very short interval and is just a momentary change in the pressure drop. If the flow rate is maintained, the pressure drop will move again into range E and the cycle will be repeated.

Curve B is shown moving from range E to range F.sub.1 which is the pressure range that closes pressure switch assembly 18. Here again, for illustration purposes, the curve of Delta P is shown dropping through the range closing the switch momentarily (time period D.sub.5), but long enough to start a build up of charge on capacitor 38a, then returning into the pressure zone and holding switch 18 closed long enough (time period D.sub.6), for time delay circuit 38 to time out. When this occurs, as explained above, relay 39 will return stepper switch 28 to its original starting point, deactuating all of the devices previously actuated, which, in the example shown, would be the two or more that are actuated by the first and second positions of the stepper switch.

In the example described, the flow rates are adjusted to cause timing circuit 23 to time out in sequence and step switch 28 twice. By maintaining this flow rate, the switch can be stepped as many times as desired. Also, after the downhole device is actuated, the driller may want to return to normal flow rates. This he can do and even stop pumping altogether to make a connection or whatever without affecting switch 28. At a later time, he can return the flow rate to provide a pressure drop within range F and deactuate the device.

As explained above, solenoid 27 closes outlet 29a of pump 29 directing the discharge of the pump under piston 33 to raise valve element 35 and create a pressure signal in the fluid stream. The closer the valve element comes to valve seat 36, the greater the pressure drop for a given flow rate. This increases the upward force required of piston 33 and the pressure of the fluid under the piston. Usually, solenoid 27 will be deenergized before the pressure drop builds up too much or the passageway is closed off. However, to be safe, check valve 49 is designed to release the fluid pressure under the piston when it reaches a preselected amount.

The alternate embodiment of the invention, shown in FIGS. 5A and 5B, is designed to also actuate a device when a differential pressure within a preselected range is applied to the apparatus and maintained for a predetermined finite period of time. The apparatus is all carried by pipe section 50 in which is located instrument housing 51. Housing 51 is shown in one piece for simplicity, although in practice it would probably consist of many separate parts. The upper end portion 51a of tubular member 51 has opening 52 of reduced diameter to provide a flow restriction for the fluid being pumped through the pipe string. Pipe joint 50 is connected into a pipe string in the conventional manner. Housing 51 may be held in axial position within pipe joint 50 by tool joints or any suitable method.

Combining with orifice 52 to restrict the flow of fluid through the orifice is valve element 53 that is supported by rod 54. The rod extends through the valve element and is connected to cap 55 that holds the valve element in position on the rod against upwardly facing shoulder 56. The valve element telescopes over annular guide 57 which is an integral part of housing 51.

Valve rod 54 extends through guide 57 and into cylinder 60. Piston 61 is located in the cylinder and attached to the rod to cause the rod to move when the piston is subjected to a different pressure in the cylinder. The rod extends downwardly into elongated opening 62 in selector valve body 51h. Valve rod 54 has central opening 54a of relatively large diameter that extends from the lower end to where it connects with central opening 54b of smaller diameter in the upper portion of the rod. Coil spring 64 is located in opening 54a with one end engaging partition 58. The other end engages the bottom of opening 62 to resiliently urge the rod and valve element 53 upwardly into position to restrict the flow of fluid through orifice 52. When fluid is being pumped down the pipe string, the pressure of the fluid upstream of orifice 52 will act against valve element 53 and urge it downwardly against the upward force of spring 64. The fluid upstream can also enter cap 55 through ports 55a and pass through lateral ports 54c into central opening 54b of the valve rod. From opening 54b, the fluid can flow into cylindrical cavity 53a of valve element 53 through passageway or opening 54a and port 54d. The fluid entering cavity 53a will be at substantially the same pressure as the fluid upstream of orifice 52 and will act upwardly against the upper end of cavity 53a to resist downward movement of valve element 53. The clearance between guide 57 and valve element 53 is such that it will sufficiently restrict the flow of fluid from cylindrical cavity 53a that pressure will build up in the cavity and exert such an upward force.

For a given flow rate then, valve element 53 will move valve rod 54 downwardly to a given position, such as the one shown in FIG. 5A. In this position, port 65 in the lower end of the rod will be in alignment with annular groove 66 on the wall of opening 62. This allows fluid from upstream of orifice 52 to flow into chamber 69 through lateral port 68. Within the physical space limitations available, any given number of ports 68 and chambers 69 can be provided, each one designed to actuate a different downhole device, as will be described below. As to which device is to be actuated, of course, it will depend upon the position of rod 54 and this, in turn, is dependent upon the rate of flow of fluid through orifice 52.

Located in chamber 69 is bellows 70. The upper end of the bellows is connected to rod 71, which extends through bellows base 72. Cylindrical body portion 51h of housing 51, in which cavity 69 is located, includes annular flange 74 to support the base of the bellows in the cavity. Nuts 75, in engagement with threads on the lower end of the base, clamp the bellows base to the annular flange. Seal ring 76 prevents the flow of fluid from chamber 69 past the bellows base. In this embodiment of the invention, this bellows assembly provides the timer for the apparatus.

The fluid in chamber 69 is at or a little below upstream pressure. The fluid inside bellows 70 and in chamber 77 below the bellows is maintained at the pressure adjacent this portion of the apparatus, which is downstream of the orifice and a lower pressure than that upstream. The pressure differential across bellows 70 will cause it to collapse or contract moving rod 71 downward through the central opening in base 72. This will displace fluid from inside the bellows into chamber 77 through the annular space between the rod and the opening in the base.

For pressure differentials within a preselected range, the annular space can be designed to require a finite minimum period of time for a sufficient volume of the fluid in bellows 70 to be displaced for rod 71 to move into engagement with rod 82. The upper end of bellows 81 is attached to rod 82 and the lower end is attached to bellows base 83 to provide a seal between the rod and bellows base 83 while allowing the rod to reciprocate. Snap ring 84 supports the base and bellows in the lower end of chamber 77. Seal ring 83a is carried by the base to maintain a seal between the bellows base and body 73.

Valve stem 87 extends into chamber 77 in axial alignment with rod 82 and with its upper end adjacent the lower end of the rod. The valve stem extends downwardly through openings 85 and 86 into chamber 94. The lower end of the stem is connected to valve head 88 which engages seat 88a and isolates opening 86 from chamber 94. Valve head 88 is held against its seat by coil spring 89.

The apparatus just described is designed for bellows rod 82 to be moved downwardly by rod 71 after a predetermined period of time and move valve element 88 away from seat 88a. This allows fluid to flow from chamber 94 to passageway 91 which causes fluid pressure to be supplied to the device to be actuated in a manner described below. Chamber 94 is supplied with fluid at upstream pressure from chamber 98 by port 93. Passageway 101 conducts fluid at upstream pressure from chamber 62 to chamber 98. Piston 97 is located in chamber 98 for purposes to be described below, but port 97a in the piston allows fluid to flow to port 93 with only a small pressure drop. Passageway 92 connects chamber 94 to ambient pressure at all times to help keep a pressure differential from building up between the inside cavities of the housing and the outside when the apparatus is not being operated. The diameter of passageway 92 is such that the flow of fluid through it will not appreciably drop the pressure in chamber 94. Appropriate seals (not shown) are provided to isolate passageway 91 from the pressure in chamber 94 except when valve 88 is open. Thus, with the apparatus described, for a given flow rate and pressure drop across orifice 52 that is held for a predetermined finite period of time, the downhole device can be actuated.

As bellows 70 moves rod 71 downward into engagement with rod 82, fluid is displaced from bellows 70 into chamber 77. To keep the pressure in chamber 77 from increasing above ambient, an arrangement (not shown) like sleeve 20 described above and shown in FIG. 1A can be used.

Means are provided to hold valve element 88 open after upstream pressure is removed from above bellows 70 so that the device will continue to be actuated, while other flow rates are selected to actuate additional devices or to return to drilling operations or the like. In the embodiment shown, pin or pawl 90 is urged to the right by coil spring 95 so that the sharp edge on the end of the pawl will engage the circumferential grooves 96 in the valve stem. Grooves 96 have flat walls on their low side and tapered walls on the upper side. These tapered walls will cam the pawl to the left and out of the way as the valve stem moves down to open the valve. The flat walls, however, will not exert a lateral force on the pawl and the pawl will prevent upward movement of the valve stem and hold the valve open.

Some means should be provided to close the valve when it is desired to cancel the operation of the device. In the embodiment shown, piston 97 is located in chamber 98 of housing area 51h and its upper end has a sharp circular edge to engage bevel 99 on the pawl. Coil spring 100 urges piston 97 upward from the position shown which movement will cause its upper end to cam pawl 94 to the left. Such movement will release valve stem 87 for upward movement, allowing spring 89 to close the valve and deactivate the device. In this embodiment, the device will be deactivated when there is no flow through the pipe string. When there is flow, fluid from the inside of chamber 62, which is at the pressure of the fluid upstream of orifice 52, can flow downwardly through passageway 101 and act against piston 97 urging it downwardly to the position shown where pawl 94 is free to move to the right to hold the valve open. When flow is stopped, the pressure across piston 97 equalizes and spring 98 will move it upwardly causing it to cam the pawl to the left and release the valve stem, thereby deactivating the downhole device.

It may be preferable to provide a time delay between the stopping of flow and the release of the valve stem to allow circulation to be stopped momentarily, as when adding another joint to the pipe string, without deactuating the device. This can be done, for example, by using a double bellows arrangement like bellows 70 and 81 to move a beveled surface to cam pawl 90 to the left after a predetermined period of time.

As explained above, the position of control rod 54 determined which of the plurality of grooves 66 is supplied with actuating pressure and which of the plurality of downhole devices is actuated. The position of the control rod is determined by the pressure drop through orifice 52, which is a function of the rate that fluid is pumped through the pipe string. Thus, for each position of the control rod, the pressure upstream of orifice 52 will be different and the pressure of the actuating fluid supplied to passageway 91 will be different.

It may be desirable or necessary to supply each downhole device with actuating fluid having a pressure different from the pressure of the fluid in passageway 91. Therefore, it is one of the features of this invention to provide means for controlling the pressure of the actuating fluid supplied to each of a plurality of devices. In the embodiment shown, passageway 91 extends downwardly through the cylindrical portion of the housing where it is connected to portion 51g of the housing that is supported in the center of the housing by rib 51e. Portion 51f of the housing provides orifice 107 through which the fluid flowing in the pipe string must pass. Valve element 108 is urged upwardly toward a position to close orifice 107 by coil spring 109 that extends from the bottom of bore 110 in housing portion 51g over which the valve member telescopes. The telescoping portion of the valve member is cylindrical skirt 112 that forms cavity 113 between the upper end of housing portion 51g and valve member 108. Fluid flowing through passageway 91 enters cavity 113 through passageways 114, 115, 116, and 117.

Located in passageway or cavity 115 is flow restriction 118 that limits the rate fluid can flow into chamber 113. The cross-sectional area against which the fluid acts in chamber 113 is greater than that of orifice 107 so that with sufficient pressure in chamber 113, the valve element can be closed. As it is urged toward the closed position, the upstream pressure, of course, will increase providing passageway 91 with the increased pressure upstream of the orifice. Consequently, by arranging check valve 119 to open at the preselected pressure desired, valve element 108 will be positioned by the upstream pressure fluid to produce this pressure after which check valve 119 will open and this pressure will be maintained. The increase in upstream pressure and the pressure in passageway 91 caused by orifice 107 does not change the position of control or selector rod 54 since the pressure differential across orifice 52 does not change, as both upstream and downstream pressure across this orifice are affected equally.

A plurality of devices may be supplied with fluid of different pressure with this apparatus. Each device is connected to a passageway, such as passageway 91, through which actuating fluid is supplied to the device. Each passageway is connected into chamber 113 through its own set of check valves 119 and 120. As explained above, check valve 119 controls the pressure supplied to the device, whereas check valve 120 allows the other devices to be supplied with different pressures by keeping the pressure in chamber 113 from entering passageway 117 when this particular set of passageways is inoperative. Fluid continuously bleeds from chamber 113 through port 121 to insure that the valve element doesn't become locked in some position. The rate of flow of fluid through port 121, however, is sufficiently low not to affect the overall operation of the apparatus.

When not operating the apparatus, it is generally desirable to allow fluid to flow through the pipe string as freely as possible and with a minimum of restriction. Consequently, it's another feature of this invention to provide means for moving valve element 53 substantially out of position to restrict the flow through orifice 52. In the embodiment shown, as the rate fluid is pumped increases toward normal circulation rates, the upstream pressure will increase and valve element 53 will move control rod 54 downwardly until port 54d enters the bore of rod guide 57. The clearance between the rod and the bore of the rod guide is such that the flow of fluid from port 54d is reduced to the point where it cannot build up pressure in chamber 53a. At the same time, port 54e moves into the upper end of chamber 60 and now the fluid upstream of orifice 52 acts against piston 61 which will force valve element 53 and rod 54 downwardly to the limit of their downward travel away from orifice 52. This opens up the orifice to reduce to a minimum the pressure drop therethrough during times that the apparatus is inoperative. Check valves 122 and 123 in housing portions 51f and 51a, respectively, allow reverse circulation and also allow the pipe string to fill up while it is being run into the hole.

In the other embodiment of the invention shown in FIGS. 6-8, all of the apparatus is located in housing 130, which consists essentially of upper cap 182, body 140, enclosure 132 and lower cap 183. As shown in FIGS. 7 and 8, the housing is supported in the center of pipe string 131 by arms 133 radially extending between the housing and cylindrical support 184. The natural pressure drop in the fluid flowing past the restriction to flow offered by the housing and support arms is employed to actuate this device when given preselected pressure differentials are held for predetermined finite periods of time.

Located in upper cap 182 of the housing is bellows 134. It is exposed externally to the pressure of the fluid in the pipe string adjacent the upper end of the housing through one or more ports 135 extending through the cap. The upper end of the bellows is connected to disc 136. Rod 137 is attached to the disc and extends through rod guide 138. The lower end of the bellows is attached to bellows base 139, which is integrally attached to rod guide 138. The base of the bellows is connected to the upper end of body 140, and forms one wall of cavity 141 in the body. The fluid in bellows 134 is discharged through ports 142 into cavity 141, when the pressure on the outside of the bellows exceeds that on the inside.

A pressure differential is created across the bellows when fluid is pumped down the drill pipe. The pressure on the outside of the bellows is that of the fluid adjacent ports 135. Everything in body 140 below valve 145 and above annular diaphragm 143 (FIG. 6B) is filled with fluid and sealed from the effect of outside pressure except through bellows 134, valve 145, and flexible diaphragm 143. These two pressure sensing elements, bellows 134 and diaphragm 143, are spaced apart longitudinally in the housing so that the ambient pressure at the upper end of the housing is greater than that adjacent diaphragm 143, and it is this difference in pressure that is used to operate the apparatus by causing bellows 134 to collapse forcing fluid out of the bellows into chamber 141.

Bellows 144 is located in cavity 141 with its lower end attached to body 140. Its upper end is attached to disc 145a of valve spool 145. The bellows seals the upper end of elongated chamber 143 in which valve spool 145 is located. Cavity 141 has lower extension 147 that is connected to valve chamber 143 by passageway 148 that divides into two branches, an upper and a lower. The valve spool is in sealing engagement with the wall of cavity 143 except for the two spaced portions of reduced diameter. Passageway 146 connects valve chamber 143 to the inside of bellows 150 in cavity 153.

As shown, the valve spool is positioned to prevent the flow of fluid from cavity 147 to passageway 146. At a preselected differential pressure across bellows 134 produced by a preselected flow rate, the pressure will build up in chamber 141 sufficiently to collapse bellows 144 far enough to move the valve spool downwardly far enough to position the lower portion of reduced diameter of the spool adjacent the lower branch of passageway 147 and the upper end of passageway 146. The higher pressure fluid in cavities 144 and 147 will then flow to the inside of bellows 150 through passageway 146. This will cause bellows base 151 and splined rod 152 to move downwardly in chamber 153. Splined rod 152 engages matching splines on eccentric weight 154. The weight is mounted in cavity 155 by bearings 156 for free rotation around the longitudinal axis of the housing. The lower end of splined rod 152, when moved downwardly by bellows 150, moves into engagement with gear 157 (FIG. 8). This gear is mounted on shaft 158. Pinion 159 is mounted on the shaft and is in engagement with gear 160, which in turn engages ring gear 161 mounted on the inside of the housing. One-way clutch 162 prevents gear 157 and shaft 158 from rotating except in one direction. The eccentric weight will seek the low side of the hole and tend to remain stationary as the pipe string is rotated. There will usually always be a low side. If the well bore is substantially vertical, the tendency of the eccentric weight to remain stationary may not be sufficient for the operation of the apparatus. If this is anticipated to be a problem, a gyroscope can be substituted for the eccentric weight in the manner described in my copending application, Ser. No. 409,176, filed Oct. 24, 1973.

With the gears in engagement with each other and with splined rod 152, rotation of the drill pipe will rotate ring gear 161 with it. Splined rod 152 will remain stationary and gears 157 and 159 will walk around the ring gear and splined rod, respectively, and in doing so, cause valve selector assembly 163 to rotate around its longitudinal axis, which also is the longitudinal axis of the pipe string.

The valve selector assembly includes shaft section 163a which extends through valve body 164. Cam plate 165 is attached to the lower end of shaft 163a. As shaft 163a rotates cam plate 165 relative to valve body 164, cam 165a engages successively the stems of the valve elements carried by valve body 164. As shown in FIG. 6, cam 165a is in engagement with the stem of valve 166 and has raised it off its seat to allow fluid to flow from chamber 167 to passageway 168 which continues into spacer member 169. From there, the passageway passes through one of ribs 133 of the housing and downwardly to the device that this valve controls. Further rotation of the drill pipe will cause cam plate 165 to allow valve 166 to close. Continued rotation will open valve 170 allowing fluid to move from cavity 167 to passageway 171 which, as shown in the drawings, is connected to passageway 172 through spacer 169 and rib 133. Passageway 172 is connected to a downhole device to be actuated when fluid under pressure is supplied to it through passageway 172.

The number of rotations of the drill pipe required to rotate cam plate 165 to open valves 166 and 170 is known and is a function of the gear ratio of the gear train between the ring gear rotated by the drill pipe and the splined rod. When cam plate 165 is in position to actuate the desired device, normal operations can be resumed. Increased circulation will provide an increase in the pressure drop across housing 130 and increase the pressure drop across bellows 144. For normal drilling operations, this is sufficient to move valve spool 145 to a position to cut off any further flow of fluid to any of the parts of the device below the control valve. The spring action of bellows 150 will move splined rod 152 upwardly out of engagement with gear 157 and rotation of the drill pipe will not affect the position of cam 165a. This allows the device selected to continue to operate while further operations are being performed, such as drilling.

To deactivate the device and return the apparatus to its starting position, a particular flow rate is used to provide a pressure differential across bellows 144 that will position valve spool 145 to connect chamber 141 to passageway 173 through the upper branch of passageway 148. This introduces fluid at upstream pressure to the annular space between bellows 174 and 175 which moves bearing housing 176 downwardly carrying valve selector assembly 163 with it. Such movement moves gear 160 out of engagement with annular ring gear 161. Clock spring 177 has one end attached to selector assembly 163 by pin 178 and the other end connected to stationary housing member 179 by pin 180. When gear 160 moves clear of the ring gear, spring 177 will rotate the valve selector assembly, including cam plate 165, back to the position where pin 178 is in engagement with stop 181. This places the cam plate in a known position relative to the valves that control the downhole devices, and when it is desired to actuate a particular downhole device, the number of rotations of the drill pipe that are required to open the desired valve will be known.

To avoid deactuating a device inadvertently while passing through the pumping rate that would position the valve spool to do this, passageway 173 is of a diameter such that the flow of fluid through it, plus the capacity of the space between bellows 174 and 175 and the distance the selector assembly must move to disengage the gears, takes some time, the amount of which can be selected. Thus, there is a built-in time delay before a device can be deactuated.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the method and apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the method and apparatus of this invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Claims

The invention having been described, what is claimed is:

1. A method of actuating a downhole device in a drill string comprising pumping fluid down the drill string at a rate to provide a pressure drop across a flow restriction within a preselected range that is different from the range of pressure drops produced during normal drilling operations, maintaining said pumping rate for a predetermined, finite, period of time and actuating said downhole device at the end of the time period.

2. The method of claim 1 with the further step of creating a pressure pulse in the fluid in the drill string that is detectable at the surface when the device is actuated.

3. The method of claim 1 with the further step of pumping fluid down the drill string at a second rate to provide a pressure drop across a flow restriction within a second different preselected range and maintaining said second rate for a predetermined, finite, period of time to deactuate said downhole device.

4. The method of claim 1 with the further step of stopping the pumping of fluid to deactivate the downhole device.

5. A method of actuating one of a plurality of downhole devices carried by a drill string comprising pumping fluid through the drill string to create a pressure drop across a flow restriction within one of several preselected ranges that are different from the range of pressure drops produced when pumping fluid during normal drilling operations, maintaining said pressure drop for a predetermined, finite period of time and actuating one of said downhole devices at the end of the time period.

6. A method of actuating a plurality of downhole devices carried by a drill string comprising pumping fluid through the drill string at a rate to create a pressure drop across a flow restriction within a preselected range that is different from the range of pressure drops produced during normal drilling operations, maintaining the pumping rate for a predetermined, finite period of time to actuate one of said devices after the time period has elapsed, and maintaining the pumping rate for additional predetermined, finite periods of time to actuate another of said devices for each additional elapsed time period the pumping rate is maintained.

7. The method of claim 6 with the further steps of pumping at a second rate to produce a second pressure drop across the flow restrictions and maintaining said second pumping rate for a predetermined, finite period of time to deactuate said devices.

8. A method of actuating one of a plurality of devices carried by a drill string comprising pumping fluid through the drill string to provide a pressure differential, maintaining the pressure differential for a predetermined, finite, period of time, and rotating the drill string a predetermined number of revolutions to actuate said device.

9. The method of claim 8 with the further step of pumping fluid through the drill string at a rate to produce a second pressure drop and maintaining said pumping rate for a predetermined, finite minimum period of time to deactuate said device.

10. Apparatus for actuating a downhole device carried by a drill string comprising timing means carried by the drill string, means responsive to a preselected pressure condition in the drill string to cause the timing means to operate while said pressure condition exists, and means to actuate said downhole device when the timing means times out.

11. The apparatus of claim 10 further provided with means to deactuate the device including a second timer, means to cause the second timer to operate through a timing cycle when a second preselected pressure condition exists, and means to deactivate the device when the second timer times out.

12. Apparatus for actuating a downhole device carried by a drill string comprising means for creating a pressure drop when fluid is pumped down the drill string, a timer carried by the drill string, means responsive to said pressure drop when it is within a preselected range to actuate the timer and to allow it to operate as long as the pressure drop is within said range, and means to actuate said device when the timer times out after a predetermined finite period of time.

13. The apparatus of claim 12 further provided with means to deactuate the device including a second timer and means to actuate the timer and to allow it to operate as long as the pressure drop is within a preselected second range, and means to deactivate the device when the timer times out after a predetermined finite period of time.

14. Apparatus for actuating a plurality of downhole devices carried by a drill string extending into a well bore, comprising timing means carried by the drill string, means responsive to a preselected pressure condition in the drill string to cause the timing means to operate while said pressure condition exists, and means to actuate one of said devices each time the timing means times out.

15. The apparatus of claim 14 further provided with means for creating a surface detectable signal as each device is actuated.

16. The apparatus of claim 14 further provided with second timing means, means responsive to a preselected pressure condition in the drill string to cause the second timing means to operate while said pressure condition exists, and means for deactivating said devices when the second timer times out.

17. The apparatus of claim 14 in which the means to actuate one of said devices includes means responsive to rotation of the drill string to actuate additional devices.

18. The apparatus of claim 14 further provided with means to provide a preselected pressure differential for each of the devices when actuated.