Method and a device for regulating a fluid flow between an outside and an inside of a well pipe

Abstract

A method and a device for regulating a fluid flow in a reservoir (1) between the outside and the inside of a well pipe (6), where the fluid flow has a different temperature from that of the reservoir (1), and where a temperature controlled valve (18) arranged to regulate a fluid flow between the outside and inside of the well pipe (6) is controlled by temperature changes in said temperature controlled valve (18) or well pipe (6).

Description

This invention regards a method of regulating a fluid flow between the outside and the inside of a well pipe. More particularly, it concerns a method in which a temperature controlled valve placed between the inside and the outside of a well pipe is influenced by the temperature of a fluid at the valve. The method is particularly suited for use during steam injection into a reservoir, and in cases where it is desirable to prevent steam and any unwanted hydrocarbons from flowing into the well pipe. The invention also comprises a device for implementing the method.

In this context the term well pipe is taken to mean any form of hollow body used to recover well fluid from a reservoir or to inject fluid into the reservoir.

It is known to use water vapour, hereinafter termed steam, to heat well fluid in a reservoir where the well fluid has a relatively high viscosity. The purpose of such steam supply is to reduce the viscosity and with this increase the rate of production from the reservoir.

In prior art steam is introduced into the reservoir in an injection well through the bore of a pipe and may be distributed from the bore via associated distributing means such as nozzles.

The intention is that the steam from the distributing means should, on the whole, distribute evenly throughout the reservoir and heat the well fluid to make it flow more easily to a well pipe (production well) located in the reservoir.

However, it has proven difficult to achieve a uniform distribution for the flow of steam throughout the reservoir. Typically, after a while, areas will form where the steam flows relatively unhindered from the bore of the pipe and into the production well. Such a flow of steam is undesirable as it leads to a loss of valuable steam.

It is known to place inlet regulating valves in a production well. Thus, GB Patent application 2 371 578 concerns a flow control valve arranged to be controlled by an electrical signal or by the well temperature. However, this valve is not arranged to regulate the flow by use of different well fluid temperatures.

The object of the invention is to remedy the disadvantages of prior art.

The object is achieved in accordance with the invention, by the characteristics stated in the description below and in the following claims.

A well pipe, typically a production tubing, provided with a number of temperature controlled valves, hereinafter termed valve, located in the reservoir along its longitudinal extent, is placed in a production well. The valves are arranged to open and close for fluid flow between the outside and inside of the production tubing.

A number of annular packings are placed in an annulus defined by the production tubing and the well wall, alternatively the production tubing and the liner or sand screen in the well.

The annular packings, which are arranged to sealingly divide the annulus into annulus sections, are distributed along the production tubing in such a way that at least one valve is in each annulus section.

The valve remains open as long as heated fluid flows in through the valve from the adjacent annulus and into the production tubing.

The valve will shut off the flow upon inflow of steam or high temperature hydrocarbons into the annulus in question.

This will then prevent steam from flowing into the production tubing to any appreciable extent. Consequently, the available steam can be utilized to heat the well fluid flowing into the production tubing via other well sections.

In a preferred, relatively simple embodiment of the valve the production tubing is provided with a through opening in the pipe wall. A slide is displaced between an open position in which the slide does not cover the through opening, and a closed position in which the slide covers the opening.

The slide can be placed in the bore of the production tubing or externally about the production tubing and be controlled by a relatively long body that has a different coefficient of expansion from that of the production tubing. The principle of operation of the valve is explained in greater detail in the specific part of the application.

If so desired, the valve can be a separate part connected to the production tubing. If so desired, the valve can be overridden by an electrical heating element at the long body.

If so desired, temperature controlled valves according to prior art can be used for said purpose.

The method and device according to the invention are also suitable for stopping incoming gas that as a result of a pressure drop experiences a reduction in temperature; for shutting off injected water that is somewhat colder than formation fluids; and for regulating the inflow of injection water in a water injector by throttling the relatively cold injection water by means of a sensing device on the outside of the well pipe.

The following describes a non-limiting example of a preferred method and embodiment illustrated in the accompanying drawings, in which:

FIG. 1 schematically shows a well formation in which a pipe has been inserted for introduction of steam, and where a production tubing is provided with a number of temperature controlled valves, the annulus between the production tubing and the well wall being divided up by means of annular packings;

FIG. 2 shows in a larger scale a sectional view of an open temperature controlled valve; and

FIG. 3 is a sectional view of the temperature controlled valve of FIG. 2 in the closed position.

In the drawings reference number 1 denotes a reservoir in the ground, containing a relatively viscous well fluid.

A pipe 2 for introducing steam into the reservoir 1 has been inserted in the reservoir 1. A production well 4 is also provided in the reservoir 1.

A well pipe 6 (production tubing) encircled by a number of annular packings 8 distributed along the length of the production tubing 6, is provided in the production well 4.

The annular packings 8 divide an annulus between the wall of the production well 4 and the well pipe 6 into sections, of which a first, a second and a third section marked 10, 12 and 14, respectively, are shown in FIG. 1.

At each section 10, 12, 14 the well pipe 6 has been given through openings 16 through which fluid from the reservoir 1 can flow into the well pipe 6.

Each opening 16 is provided with a temperature controlled valve 18 arranged to open and close for fluid flow between the outside of the well pipe 6 and its bore.

The valve 18, see FIG. 2, comprises the opening 16 that goes through the pipe wall of the well pipe 6. A slide 22 is arranged to be displaceable and to seal against the through opening 16. The slide 22 is arranged to be moved between an open position in which the slide 22 does not cover the through opening 16 and a closed position in which the slide 22 covers the opening 16.

The slide 22 is connected to one end portion of a relatively long body 24, the opposite end portion of which is connected to the well pipe 6. The material of the long body 24 has a linear expansion coefficient that is greater than that of the well pipe material. When the temperature increases, the long body 24 expands more than the well pipe 6, whereby the slide 22 moves in the direction of its closed position covering the opening 16.

A jacket 26 encloses the long body 24 and is arranged to guide the fluid flow from the corresponding opening 16 towards the long body 24, thus to prevent the long body 24 from being affected to any significant degree by the temperature in the rest of the fluid flowing in the well pipe 6.

Steam passed from the bore 2 into the reservoir 1 condenses after flowing a distance into the reservoir formation. The dotted line 28 in FIG. 1 indicates where in the reservoir 1 the steam is condensed.

Steam flows through the reservoir and into the third section 14, from where the steam flows on into the well pipe 6. The temperature controlled valve 18 corresponding to the third section 14 is about to shut off the fluid flow from the third section 14 into the well pipe 6.

The fluid flow from the other sections 10 and 12 is substantially unaffected by the steam breakthrough into the third section 14.

Known annular packings 8 may be used. It has proven advantageous to use a swelling annular packing 8, where the material of the annular packing 8 is caused to swell upon contact e.g. with hydrocarbons.

In alternative embodiments (not shown) the temperature controlled valves 18 may be electrically heated valves according to prior art known per se.

Claims

1. A method of regulating a fluid flow in a reservoir (1) between the outside and inside of a well pipe (6), where the fluid flow has a different temperature from that of the reservoir (1), characterized in that a temperature controlled valve (18) arranged to be able to regulating a fluid flow between the outside and inside of the well pipe (6), is controlled by temperature changes in said temperature controlled valve (18) or well pipe (6).

2. A method in accordance with claim 1, characterized in that at least one annular packing (8) is arranged in an annulus defined by the well pipe (6) and a production well (4) in which the well pipe (6) is placed, alternatively the lining or sand screen of the production well (4).

3. A method in accordance with claim 2, characterized in that two annular packings (8) define a section (10, 12, 14) in which there is provided at least one temperature controlled valve (18).

4. A method in accordance with claim 1, in which steam is made to flow into the reservoir (1) and in the direction of the well pipe (6), characterized in that the temperature controlled valve (18) arranged to be able to regulating a fluid flow between the outside and inside of the well pipe (6) closes upon temperature changes in said temperature controlled valve (18) or well pipe (6).

5. A method in accordance with claim 1, characterized in that the temperature controlled valve (18) is overridden by means of an electrical heating element.

6. A device for regulating a fluid flow in a reservoir (1) between the outside and inside of a well pipe (6), where the well pipe (6), the wall of which has at least one through opening (16), is arranged in a production well (4) in the reservoir (1), characterized in that the opening (16) is provided with a corresponding temperature controlled valve (18), where the valve (18) is arranged to be controlled by the temperature in the fluid flowing through the corresponding opening (16).

7. A device in accordance with claim 6, characterized in that at least one annular packing (8) is arranged in an annulus defined by the well pipe (6), or another similar body, and the wall of the production well (4), alternatively the lining or sand screen of the production well (4).

8. A device in accordance with claim 7, characterized in that two annular packings (8) define a section (10, 12, 14) in which at least one temperature controlled valve (18) is provided.

9. A device in accordance with claim 6 where the temperature controlled valve comprises a slide (22) that is sealingly displaceable against the through opening (16), characterized in that the slide (22) is connected to one end portion of a long body (24), wherein the opposite end portion of the long body (24) is connected to the well pipe (6), the linear expansion coefficient of the long body (24) being different from the linear expansion coefficient of the production tubing (6).

10. A device in accordance with claim 9, characterized in that the long body (24) is enclosed by a jacket (26), the jacket (26) being arranged to guide fluid flowing through the corresponding through opening (16) to the long body (24).