WO2007049968A1

WO2007049968A1 - An electric control system for use for activation and position control of rotary valves in an oil well

Info

Publication number: WO2007049968A1
Application number: PCT/NO2006/000369
Authority: WO
Inventors: Per Olav Haughom; Nils Reimers
Original assignee: Tomax As
Priority date: 2005-10-26
Filing date: 2006-10-23
Publication date: 2007-05-03
Also published as: NO20064665L; NO324981B1

Abstract

A device for the operation and position control of several rotary valves (12a, 12b) , each comprising a valve jacket (61) with a number of outer valve openings (63) extending therethrough and an internal valve stem (62) with a number inner valve openings (64), the valve stem (62) being rotatably supported in the valve jacket (61) and there being connected to each rotary valve (12a, 12b) an actuator (24) surrounding the valve stem (62) or an extension (22) thereof, the actuator (24) being surrounded by the valve jacket (61) or an extension (21) thereof, the actuator (24) being arranged to be activated when the actuator (24) is supplied with an electric signal pulse train (17) exhibiting a frequency lying within a defined range.

Description

AN ELECTRIC CONTROL SYSTEM FOR USE FOR ACTIVATION AND POSITION CONTROL OF ROTARY VALVES IN AN OIL WELL

This invention relates to a system for use in the activation and position control of rotary valves, in particular of the kind preferably used in connection with the inflow control from hydrocarbon-bearing zones in oil and gas wells.

Oil and gas are extracted from hydrocarbon-bearing zones down in the earth's crust. To utilize the deposits, a hole is drilled down to the oil- and gas-bearing zones of interest. The hole is then cased with steel pipes (casing) which are fixed by cementation to the surrounding rock formations with concrete between the steel pipe and the formations.

Inside the casing, production tubing is set down to lead hydrocarbon fluids up to the surface. The oil and gas often come from zones of different pressures, and therefore it is necessary to control the inflow from the different zones to have maximum utilization of the resources available. To control the inflow, valve systems are used, which can be remote-controlled from the surface by means of hydraulic or electric signals. A particular type of valve is called a rotary valve. It consists, in principle, of an outer and an inner cylindrical string part with radial holes. By rotating the inner part, the valve is adjusted between the fully closed and fully open states and also intermediate opening states.

Valves of this type are described in further detail in the NO patents 312734 and 313341, among others.

The opening and closing of such valve systems are currently carried out with electro-hydraulic control systems from the surface. These systems are complicated and expensive, especially when several valves are to be activated and feedback on valve position is to be given.

The technological development has recently gone in the direction of subsea installations, that is to say installations which are placed on the seabed. With such installations it will often be complicated to make use of electro-hydraulic control systems for the control and monitoring of valves down in the oil well because many and long hydraulic control lines (pipes) and passages in the well head are required.

US 2001/0054504 Al discloses a rotary valve which can be controlled by means of electric systems, an electric motor combined with gears, among other things.

NO 312734 also discloses the use of electric systems for controlling a rotary valve.

US 4 886 114 discloses a solenoid-operated valve which is controlled electrically from the surface, the valve comprising an activation tube with sections of different magnetic characteristics, so that less energy is required to keep the valve open than that required for the opening of the valve. The position of the valve can be indicated by measuring the relevant power consumption in the circuit.

US 4 573 536 discloses a purge valve, in which the drill string can be oscillated rotationally to drive a ratchet mechanism at the valve to open the valve through a rotary motion.

None of the cited publications describes a technique which makes it possible to control several rotary valves through the same signal cable.

The invention has as its object to remedy or reduce at least one of the drawbacks of the prior art.

The object is achieved through features specified in the description below and in the claims that follow.

It is an object of the present invention to provide a control system which makes it possible by means of just one signal- communicating connection to control several rotary valves and at the same time monitor the position of each valve.

More particularly, the invention relates to a device for the operation and position control of several rotary valves, each including a valve jacket with a number of outer valve openings extending therethrough and an internal valve stem with a number of inner valve openings, the valve stem being rotatably supported in the valve jacket, and there being connected to each rotary valve an actuator surrounding the valve stem or an extension thereof, the actuators being surrounded by the valve jacket or an extension thereof, characterized in that the actuator is arranged to be activated when the actuator is supplied with an electric signal pulse train exhibiting a frequency lying within a defined range. The actuator of a first rotary valve is preferably balanced to a frequency range different from the frequency range of a second rotary valve controlled by the same control system.

The actuator is advantageously provided with an electromagnet and an anchor which are frequency-balanced to yield a force when the electromagnet is supplied with an electric signal pulse train exhibiting a frequency lying within a defined range .

The extension of the valve stem is advantageously constituted by an actuator stem, and the extension of the valve jacket is advantageously constituted by an actuator jacket.

The actuator is preferably placed in an annular space between the actuator jacket and the actuator stem.

The valve stem and the actuator stem are preferably each provided with a through centre bore, which are in fluid communication with each other and with a production tubing.

The actuator is preferably provided with a ratchet coupling, in which a first, driving coupling part forms the anchor of the electromagnet, the first coupling part being surrounded by an electrically conductive, first coil connected in a rotationally rigid manner to the actuator jacket, and there being placed on the first coupling part several magnets evenly spaced, and a driven, second coupling part being connected in a rotationally rigid manner to the valve stem.

The rotary motion of the first coupling part is advantageously restricted relative to the actuator jacket by a resilient stabilizing element, whose spring characteristic is matched in such a way that by a signal pulse train of a defined frequency being forced into the first coil, the first coupling part is arranged to be set into a reciprocating rotary motion at least exceeding the length of teeth of the ratchet coupling, in order thereby to impart a rotary motion to the valve stem.

The stabilizing element is preferably arranged to stabilize the first coupling part in an initial position.

A valve position indicator is preferably formed by a position indicator arranged to carry out, as the valve stem rotates and when the valve stem has been rotated through a predetermined angle, a quick, axial movement sufficient to induce a voltage in an electrically conductive second coil, an indicator lug, which is resting supportingly on the cam of an index ring, moving from the top of a first cam surface to the bottom of a second cam surface .

Between the valve stem and the second coupling part of the ratchet coupling, is/are preferably arranged one or more harmonic gears .

The first and second coils of each of the actuators together with signal-carrying lines, a signal pulse generator and a control unit advantageously form a valve control circuit.

In what follows is described an example of a preferred embodiment which is visualized in the accompanying drawing, in which:

Figure 1 shows schematically a valve system with two rotary valves mounted into a production tubing, a signal pulse generator, a control unit and signal lines;

Figure 2 shows in perspective and partially in section a valve control unit; Figure 3 shows, on a larger scale, an actuator in the valve control unit;

Figure 4 shows, on approximately the same scale, a valve position indicator of the valve control unit;

Figure 5 shows, on a smaller scale, a cross-section of a gear unit; and

Figure 6 shows in perspective a section through parts of a rotary valve .

Reference is first made to figure 1, in which the reference numeral 11 indicates a production tubing for a hydrocarbon well. In the production tubing 11 are placed, in a manner known per se, several rotary valves 12a, 12b which are each provided with a valve control unit 13a, 13b. A control unit 14 is connected in a signal-communicating manner to a signal pulse generator 15 and the valve control units 13a, 13b via signal lines 16. The signal pulse generator 15 is arranged to send a defined signal pulse train 17 through the signal lines 16. The signal pulse train 17 may be alternating voltage or chopped direct voltage of a defined frequency.

The valve control unit 13a, 13b (see figure 2) is provided with an actuator jacket 21 surrounding an actuator stem 22 provided with a through centre bore 23. The centre bore 23 form part of the centre bore of the production tubing 11 for conveying a fluid flow.

The valve control unit 13a, 13b is further provided with an actuator 24 which is located in an annular space formed between the actuator jacket 21 and actuator stem 22 and surrounds the actuator stem 22. On one side the actuator 24 is connected to two gear units 25 connected in series, typically two harmonic gears surrounding the actuator stem 22. On the opposite side of the actuator 24 is arranged a position indicator 26. The actuator 24 and position indicator 26 are connected in a signal-communicating manner to the signal line 16.

5 Reference is now made to figure 3, in which the actuator 24 is shown in greater detail. The first, driving coupling part 31 of a ratchet 30 is provided with a toothed front end portion 33 corresponding to a toothed end portion of a second, driven coupling part 32, the toothing being arranged, Q in a manner known per se, to mesh on rotation of the first coupling part 31 in one direction, and enabling the reversal of the first coupling part 31 without the second coupling part 32 rotating with it. An axially movable compression ring 35 bears on the second end of the first coupling part 31. A s coupling spring 36 exerts an axially-directed pressure on the compression ring 35 which presses, in turn, on the first coupling part 31 and provides for the coupling parts 31, 32 to bear on each other. The coupling spring 36 bears on an indicator ring 41 which is secured to the actuator jacket 21.

o The first coupling part 31 is provided, at a rear end portion, with a recess 34. A stabilizer rest 37 is secured to the actuator jacket 21, extending by a spring rest 37a into the recess 34. Two springs 38 are placed on respective sides of the spring rest 37a, bearing on the spring rest 37a and 5 the first coupling part 31 and being positioned in a manner known per se, for example by the spring ends being disposed in recesses or on projecting pins in the respective bearing surfaces. The springs 38 hold the first coupling part 31 in a stable mid position.

0 A first electric coil 39 which is connected in a signal- communicating manner to the signal line 16, is fixed to the actuator jacket 21, surrounding a portion of the first coupling part 31. In a portion of the first coupling part 31, evenly spaced round the periphery, are placed several permanent magnets 39a.

Reference is now made to figure 4. The indicator ring 41, which is fixed to the actuator jacket 21, is provided with several cams 42. The transition between two cams 42 is formed of a portion 42a lying substantially parallel to the centre axis of the valve control unit 13a, 13b.

A follower ring 43 which is connected in a rotationally rigid manner to the actuator stem 22, is movable in the axial direction of the valve control unit 13a, 13b. An indicator lug 44, possibly several indicator lugs evenly spaced around the follower ring 43 and with the same partitive length as the cams 42, project (s) in an axial direction from the follower ring 43 towards the indicator ring 41, the indicator lug(s) 44 bearing on a, possibly a respective, cam 42. An indicator spring 45 bears by its one end portion on a portion of the follower ring 42, and the other end portion of the indicator spring 45 bears on a spring rest 46 (see figure 2) which is fixed to the actuator jacket 21. Thereby, the indicator spring 45 forces the follower ring 43 in the axial direction towards the indicator ring 41.

A second electric coil 47, which is connected in a signal- communicating manner to the signal line 16, is fixed to the actuator jacket 21 and surrounds a portion of the follower ring 43.

Figure 5 shows a typical section through a gear unit 25 of the harmonic gear type. The harmonic gear consists of an outer gear rim 51 which meshes with an inner gear rim 52 arranged on a cylindrical, eccentrically supported input drive shaft 53, which may be formed, as far as one gear unit is concerned, by the second coupling part 32 of the ratchet. The inner gear rim forms the output drive shaft from the gear unit. Depending on the difference in tooth number of the outer and inner gear rims 51, 52 a high gear ratio is achieved between the rotation of the input drive shaft 53 and the inner gear rim 52 when the input drive shaft 53 is set into rotation. As an example, fifty teeth on the outer gear rim 51 and forty- eight teeth on the inner gear rim 52 will give a gearing corresponding to (50-48) /50, that is 1:25 between the input drive shaft 53 and the inner gear rim 52. With two harmonic gears of this size mounted in series and connected to appropriate couplings known per se, for example curved gear tooth couplings, an overall gear-down of 1/25 x 1/25, that is to say 1:625, is achieved.

In figure 6 the reference numeral 61 indicates a valve jacket surrounding a valve stem 62 rotatably supported in the valve jacket. The valve stem 62 is provided with a centre bore 63. The centre bore 63 forms part of the centre bore of the production tubing 11 for conveying a fluid flow. The valve jacket 61 is provided with a number of outer valve openings 64 corresponding to corresponding inner valve openings 65 in the valve stem. Each of the outer valve openings 64 of the valve jacket 61 is provided with a seal 66 bearing sealingly on the external mantle of the valve stem 62.

The springs 38 are adjusted in such a manner that there will be resonance oscillation in the first coupling part of the actuator at a particular forced frequency of the signal pulse train 17. The resonance oscillations make the ratchet coupling of the actuator drive the second coupling part in steps as long as the signal pulse train 17 at the matched frequency is forced on the actuator through the signal lines 16. To achieve a sufficiently great torque the rotational speed is shifted down through the gear units 25.

When a particular rotary valve 12a, 12b is to be activated, there is generated, by means of the control unit 14 and the signal pulse generator 15, a signal pulse train 17 of a frequency adjusted to the actuator 24 of the rotary valve 12a, 12b in question. This frequency result in the balanced actuator 24 being set into oscillation by its coil 39, whereas other actuators 24 receiving the same signal pulse train 17 and being adjusted to achieve a harmonic oscillation (internal resonance oscillation) of a different frequency, achieve such small deflections of oscillation in the first coupling part 31 of the actuator that the gear tooth coupling of the actuator will not set the second coupling part 32 into a rotating motion. By using different signal pulse trains 17 of different frequencies a great number of valves 12a, 12b may be controlled.

A very important function is feed-back on the position of the rotary valve 12a, 12b of interest. This is achieved by means of the position indicator 26. When, due to the rotation of the actuator stem 22, the follower ring 43 has reached the top of the cam 42 and moves quickly in the axial direction to the bottom of the next cam, a voltage will be induced in the second coil 47. This voltage is registered by the control unit 14 as a position indication whereby the valve movement may be stopped by stopping the generation of signal pulse 17.

Claims

C L A I M S

1. A device for the operation and position control of several rotary valves (12a, 12b) , each comprising a valve jacket (61) with a number of outer valve openings (63) extending therethrough and an internal valve stem (62) with a number inner valve openings (64), the valve stem (62) being rotatably supported in the valve jacket (61) and there being connected to each rotary valve (12a, 12b) an actuator (24) surrounding the valve stem (62) or an extension (22) thereof, the actuator (24) being surrounded by the valve jacket (61) or an extension (21) thereof, c h a r a c t e r i z e d i n that the actuator (24) is arranged to be activated when the actuator (24) is supplied with an electric signal pulse train (17) exhibiting a frequency lying within a defined range.

2. The device according to claim 1, c h a r a c t e r i z e d i n that the actuator (24) of a first rotary valve (12a) is balanced to a frequency range different from the frequency range of a second rotary valve (12b) controlled by the same control system.

3. The device according to claim 1, c h a r a c t e r i z e d i n that the actuator (24) is provided with an electromagnet (39) and an anchor (31) which are frequency-balanced to yield a force when the electromagnet (39) is supplied with an electric signal pulse train (17) exhibiting a frequency lying within a defined range.

4. The device according to claim 1, c h a r a c t e r i - z e d i n that the extension of the valve stem (62) is constituted by an actuator stem (22), and the extension of the valve jacket (61) is constituted by an actuator jacket (21) .

5. The device according to claim 3, char ac t e r i z e d i n that the actuator (24) is placed in an

5 annular space between the actuator jacket (21) and the actuator stem (22) .

6. The device according to claims 1 and 3, cha r a c t e r i z e d i n that the valve stem (62) and the actuator stem (22) are each provided with a through o centre bore (23, 63) which are in fluid communication with each other and with a production tubing (11) .

7. The device according to any one of claims l-'fc, cha r a c t e r i z ed i n that the actuator (24) is provided with a ratchet coupling (30) , in which a first, s driving coupling part (31) forms the anchor of the electromagnet, the first coupling part (31) being surrounded by an electrically conductive, first coil

(20) connected in a rotationally rigid manner to the actuator jacket (21) , and that evenly spaced on the o first coupling part (21b) there are placed several magnets (39a) , and that a driven, second coupling part (31) is connected in a rotationally rigid manner to the valve stem (22) .

8. The device according to any one of claims 1-7, c h a - 5 r a c t e r i z e d i n that the rotary motion of the first coupling part (31) relative to the actuator jacket

(21) is restricted by a resilient stabilizing element (37a, 38) , whose spring characteristic is adjusted in such a manner that at a signal pulse train (17) of a 0 defined frequency forced into the first coil (39) , the first coupling part (31) is arranged to be set into a reciprocating rotary motion at least exceeding the length of teeth of the ratchet coupling (30) in order thereby to impart a rotary motion to the valve stem (62) .

9. The device according to claim 1, c ha r a c t e r i z e d i n that the stabilizing element (37a, 38) is arranged to stabilize the first coupling part (31) in an initial position.

10. The device according to claim 1, c h a r a c t e r i z e d i n that a valve position indicator (26) is formed by a position indicator (43) being arranged to carry out, on the rotation of the valve stem (62) and when the valve stem (62) has been rotated through a predetermined angle, a quick, axial movement sufficient to induce a voltage in an electrically conductive second coil (47), an indicator lug (44), which is bearing ^' supportingly on the cam (42) of an index ring (41), moving from the top of a first cam surface to the bottom of a subsequent cam surface.

11. The device according to claim 1, c ha r a c t e r i z e d i n that between the valve stem (62) and the second coupling part (32) of the ratchet coupling (30) there is/are arranged one or more harmonic gears (25) .

12. The device according to claim 1 and 2, c ha r a c t e r i z e d i n that the first and second coils (39, 47) of each of the actuators (24) together with signal-bearing lines (16) , a signal pulse generator (15) and a control unit (14) form a valve control circuit.