Improved Autonomous Well Valve

Abstract

An improved autonomous well valve has a body that constitutes an actuator for opening and closing of first and second valves. The body has a body axis of symmetry. The body, which in operation is submerged, has an effective density that is equal or greater than the density of a first fluid and less than the density of a second fluid. The body is placed in a housing, the housing having a housing axis of symmetry. At least two first valves are designed to allow flow between the inside and outside of the housing, are distributed about the body axis and mechanically connected between the body and the housing. The body axis at the first valves is restricted from moving above the housing axis.

Description

FIELD

There is provided an improved autonomous well valve. More precisely there is provided an improved autonomous well valve having a body that constitutes an actuator for opening and closing of individual valves, the body having an body axis of symmetry, and where the body, that in operation is submerged, has an effective density that is equal or greater than the density of a first fluid and less than the density of a second fluid, and where the body is placed in a housing, the housing having a housing axis of symmetry.

BACKGROUND

When producing from, injecting into or maintaining a downhole well, a need for opening or closing flow as well as directing fluids of different densities arises.

Generally, it is advantageous to open and close, alternatively redirect flow, in or close to the well itself. Lack of reliable valves suited for such operations, combined with difficulty related to the operation of them, has made such solutions less viable. A result is for instance, that vast quantities of water is produced to the surface from petroleum wells.

NO 338579 discloses an autonomous well valve that is designed to direct flow based on variation in fluid density. The well valve does not require to be positioned in a particular orientation and may thus be used blindly. Sensitivity with respect to differential pressure may case malfunction of the well valve.

SUMMARY

The purpose of the invention is to overcome or reduce at least one of the disadvantages of the prior art.

The purpose is achieved according to the invention by the features as disclosed in the description below and in the following patent claims.

The improved autonomous well valve according to the invention is designed to direct flow in the well based on variation in fluid density. The well valve does not need to be positioned at a particular orientation and may be placed blindly in a well. A body that acts as an actuator of individual first and second valves has an effective density that is equal or greater than the density of a first fluid and less than the density of a second fluid. The well valve is less influenced by differential pressures than other valves for the same purpose.

The term “effective density” equals the weight/volume ratio of the body. The body may be hollow and be made from materials of different densities.

The invention is defined by the independent patent claim. The dependent claims define advantageous embodiments of the invention.

More specifically, the invention relates to an improved autonomous well valve having a body that constitutes an actuator for opening and closing of individual first and second valves, the body having an body axis of symmetry, and where the body, that in operation is submerged, has an effective density that is equal or greater than the density of a first fluid and less than the density of a second fluid, and where the body is placed in a housing, the housing having a housing axis of symmetry, where at least two first valves that are designed to allow flow between the inside and the outside of the housing, are distributed about the body axis and mechanically connected between the body and the housing, and where the body axis at the first valves is restricted from moving above the housing axis.

Typically, the first fluid is a fluid having a lower density than the second fluid. The first fluid may be a fluid having lower density than water, and the second fluid may be water, or the first fluid may be water and the second fluid may be a fluid having higher density than water.

The body axis may not be parallel with the housing axis. The relative position of the body axis and housing axis are therefore referenced to the actual individual first or second valves.

By having at least two first valves distributed about the body axis, the well valve may be operable at more than one orientation. By choosing a suitable number of first valves, the well valve may be operable at any orientation. The first valves may advantageously be positioned at the same position along the body, but may in some cases be staged along a part of the body.

Reference is made to the detailed part of the description for explanation of a working principle of the well valve.

When positioned above the body axis, the first valve is open when the body axis at the first valves is a predetermined distance below the housing axis, and closed when the body axis at the first valves is level with the housing axis.

The first valve that is below the body axis remains closed.

The well valve may be designed as a two-way valve. Then at least two second valves that are designed to allow flow between the inside and the outside of the housing, are distributed about the body axis and mechanically connected between the body and the housing, and where the body axis at the second valves is restricted from moving below the housing axis.

The second valve, when positioned above the body axis, is open when the body axis at the second valve is a predetermined distance above the housing axis and closed when the body axis at the second valve is level with the housing axis.

The second valve that is below the body axis remains closed.

The first and second valves may operate according to any known valve principle, such as axial or rotational relative movement and combinations thereof. When choosing the first and second valves, it is important to make sure that the first and second valves are not unduly restricting the relative movement of the body inside the housing.

Considering the first valve that is positioned above the body axis; when the body is surrounded by a first fluid of lower density than the body, the body axis is sufficiently below the housing axis at the first valves for the first valve to open. Other first valves are closed. When the fluid surrounding the body is changed from the first fluid to the second fluid, the body will rise to the limit where the body axis at the first valves reaches the housing axis. All first valves are then closed. If the fluid changes to the first fluid, a first valve will that is positioned above the body axis will open again.

Similarly, the second valves remain all closed when the body is surrounded by the first fluid and the body axis at the second valves is at its lower limit at the housing axis.

When the fluid surrounding the body is changed from the first fluid to the second fluid, the body axis will rise sufficiently above the housing axis for a second valve to open.

The first and second valves normally opens to different rooms, for instance divided by a partition, outside the housing.

In an oil producing well, the well valve may be used for shutting off production if water enters the tool, and may be used for rerouting the water to a different formation. If water disappears and oil again enters the well valve, oil production will resume. The same functionality may be used for gas production where gas stops and/or is rerouted to another formation. The tool may be used in a gas well for reducing water production.

In injection wells, the well valve may be used to control zonal flow by varying the density of the injected fluids. The well valve may be installed at selected places in the well and the direction of flow is opposite of the flow when the well valve is used for instance as a waterstop valve. If a light fluid is injected, the well valve is open and allow fluid to pass into the formation. For instance, if water or a heavier fluid is injected, the well valve will close. Many types of fluids may be used for injection purposes such as glycol water, methanol, various inhibitors, acids, gasses such as CO₂ and other fluids. The well valve may be designed to allow flow of heavier or lighter fluids. Typical operations where this will be advantageous is various workover operations.

The well valve may be symmetrical about the center axis. The well valve may then be functional in any rotational position. The actual design may render the well valve to be operational in substantially any direction.

Such a design lend itself to be used blindly, which is without any specific orientation of the well valve in the well.

The mechanism may also be used for other applications that require dedicated production/injection points such as water and gas injection (WAG) and steam assisted gravity drainage (SAGD), and workover and well stimulation and operations where fluids of different densities are pumped into the well.

More than one well valve may be positioned in series in a flow path. The different well valves may operate at different fluid densities.

Thus, the well valve according to the invention includes a mechanism that is actuated by a buoyant force that open or close one or several well valves. Uses of the well valve includes shutting off unwanted water or gas production, potentially rerouting these to a reservoir at another depth. Other uses are workover, stimulation or well intervention operations where fluids of selected densities can be placed in specific places in the well. Other uses of the well valve can be well operations where specific tools may be actuated by pumping fluids of different densities. The mechanism is also useful for injection wells, where for example alternate water and gas injection are placed in different formations in the reservoir.

The well valve according to the invention provides a reliable, simple and cost effective way of autonomous flow control in a downhole well.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following is described examples of preferred embodiments illustrated in the accompanying drawings, wherein:

FIG. 1 shows a principal sketch in cross section a well valve according to the invention in its open position;

FIG. 2 shows the same as in FIG. 1, but where the valve is in its closed position;

FIG. 3 shows a section IIa-IIa of the valve in FIG. 2;

FIG. 4 shows a section IIb-IIb of the valve in FIG. 2;

FIG. 5 shows to a larger scale a first valve;

FIG. 6 shows to a larger scale a second valve;

FIG. 7 shows a principal sketch of a two way valve; and

FIG. 8 shows the well valve positioned in a well where water is directed into a different formation.

DETAILED DESCRIPTION OF THE DRAWINGS

On the drawings, the reference number 1 denotes a well valve that includes a body 2 that in operation is submerged. The body 2 is positioned between a first member 4 and a second member 6 in a housing 8. In this preferred embodiment the members 4, 6 and housing 8 provides a room 10 for the body 2. Fluid may enter the room 10 via an opening 12.

At its first end portion 14 that is closest to the first member 4, the body 2 is provided with a central conical recess 16. Similarly, the first member 4 is provided with a conical recess 16 opposing the conical recess 16 of the first end portion 14

A ball 18 is positioned between the said conical recesses 16.

Similarly, conical recesses 16 with a ball 18 in between are provided at a second end portion 20 of the body 2 and in the second member 6. The conical recess 16 in the second member 6 constitute a body support 22.

The length of the body 2 is chosen to give room for some axial movement of the body 2 between the first and second members 4, 6. The housing 8 has a housing axis 24 of symmetry. The body 2 has a body axis 26 of symmetry.

A ball race 28 with at least one race ball 30 surrounds the body 2. The ball race 28 is fixed to the housing 8. Gravity will ensure that the at least one race ball 30 is positioned at its lowermost position in the ball race 28.

A flange like ring 32 on the body 2 abuts the race ball 30 and bias the body 2 towards the second member 6 and the body support 22 as shown in FIG. 1.

A set of first valves 34 are shown in FIGS. 1, 2 and 3. The main purpose of the items 16-22 and 28-32 is to secure that the body axis 26 is not allowed to rise above and not too far below the housing axis 24 at the first valves 34. Alternatively, other known, not shown mechanisms may be utilized for the same purpose.

In this preferred embodiment three first valves 34, see FIG. 3, are evenly spaced around the body axis 26. Each first valve 34 has a first valve body 36 that is hingedly fixed to the body 2. The first valve 34 positioned above the body axis 26 is considered below. See also FIG. 5

The first valve body 36 is slideably movable in a first valve seat 38 that penetrates the housing 8. The first valve seat 38 is hingedly fixed to the housing 8. A first channel 40 of the first valve body 36 extends from the outside of the housing 8 through the first valve body 36 and has an opening 42 that emerges in the room 10 when the body axis 26 is a predetermined distance below the housing axis 24 at the first valves 34. The first valve 34 is then open.

As a fluid of higher density is flowing into the well valve 1, the body 2 is rising in the fluid along the body support 22. The movement includes a component that moves the body 2 axially towards the first member 4 when the ring 32 is following the surface of the race ball 30. This axial movement may also be used for opening and closing individual valves not shown.

When the body axis 26 is level with the housing axis 24, the opening 42 is inside the first valve seat 38 and the first valve 36 is closed.

The opening 42 of the first valves 34 that are below the body axis 26, are at all times inside their respective first valve seat 38 and thus closed.

In the section IIb-IIb shown in FIG. 4, the ball 18 is not shown.

FIG. 7 shows an embodiment where the well valve 1 has a set of second valves 44 and where the second valves 44 are set up to make the well valve 1 a two ways valve, here shown in an inclined position. A second fluid that has a higher density than the body 2 surrounds the body 2. As the body 2 then is in its higher position in the housing 8, the first valves 34 are closed and a second valve 44 that is positioned above the body axis 26, is open, see also FIG. 6.

Each second valve 44 has a second valve body 46 that is hingedly fixed to the body 2. The second valve 44 positioned above the body axis 26 is considered below.

The second valve body 46 is slidably movable in a second valve seat 48 that penetrates the housing 8. The second valve seat 48 is hingedly fixed to the housing 8.

A second channel 50 of the second valve body 46 extends from the inside of the housing 8 through the second valve body 46 and has an opening 52 that emerges outside the housing 8 when the body axis 26 is a predetermined distance above the housing axis 24 at the second valves 44.

As a fluid of lower density is flowing into the well valve 1, the body 2 is sinking in the fluid along the body support 22 until the body axis 26 reaches the housing axis 24 at the second valves 44. All second valves 44 are then closed.

A partition 54 divides the outside of the housing 8.

FIG. 8 shows a tubing string 56 that is extending into a well 58 in the ground 60. A valve 1 is included in the tubing string 56. A pipe 62 is extending from the valve 1 and into a formation 62 in the ground 60.

When the well 58 is producing water, the body 2 of the valve 1 will be in the position shown in FIG. 7. Water will thus be directed via the opening 52 of the second valve 44 and the pipe 62 to the formation 64.

Individual first and second valves 34, 44 are shown in FIGS. 5 and 6. Other known valves, not shown may alternatively be utilized.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. An improved autonomous well valve comprising a body that constitutes an actuator for opening and closing of at least two first valves, the body having an body axis of symmetry, and wherein the body, when submerged, has an effective density that is equal or greater than a density of a first fluid and less than a density of a second fluid, and wherein the body is located in a housing, the housing having a housing axis of symmetry, wherein the first valves, which are configured to allow flow between inside and outside of the housing, are distributed about the body axis and mechanically connected between the body and the housing, and wherein the body axis is restricted from moving above the housing axis.

2. The improved autonomous well valve according to claim 1, wherein at least one of the first valves, when positioned above the body axis, is open when the body axis is a predetermined distance below the housing axis.

3. The improved autonomous well valve according to claim 1, wherein the first valves are closed when the body axis at the first valves is level with the housing axis.

4. The improved autonomous well valve according to claim 1, wherein at least two second valves, which are configured to allow flow between the inside and outside of the housing, are distributed about the body axis and mechanically connected between the body and the housing, and where the body axis at the second valves is restricted from moving below the housing axis.

5. The improved autonomous well valve according to claim 4, wherein at least one of the second valves, when positioned above the body axis, is open when the body axis at the second valves is a predetermined distance above the housing axis.

6. The improved autonomous well valve according to claim 4, wherein the second valves are closed when the body axis at the second valves is level with the housing axis.

7. The improved autonomous well valve according to claim 2, wherein the first valves are closed when the body axis at the first valves is level with the housing axis.

8. The improved autonomous well valve according to claim 2, wherein at least two second valves, which are configured to allow flow between the inside and outside of the housing, are distributed about the body axis and mechanically connected between the body and the housing, and where the body axis at the second valves is restricted from moving below the housing axis.

9. The improved autonomous well valve according to claim 3, wherein at least two second valves, which are configured to allow flow between the inside and outside of the housing, are distributed about the body axis and mechanically connected between the body and the housing, and where the body axis at the second valves is restricted from moving below the housing axis.

10. The improved autonomous well valve according to claim 5, wherein the second valves are closed when the body axis at the second valves is level with the housing axis.