CA2742084A1

CA2742084A1 - Foam level sensor

Info

Publication number: CA2742084A1
Application number: CA 2742084
Authority: CA
Inventors: Dean Schlekewy
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-06-14
Filing date: 2011-06-03
Publication date: 2011-12-14

Abstract

A foam level sensor for a production tank containing foam has a sensor element that is supported by the surface tension of the foam, and a sensor switch that is triggered upon the sensor element being raised to a predetermined height.

Description

TITLE
[0001] Foam level sensor FIELD

[0002] This relates to a foam level sensor for a production tank.
BACKGROUND

[0003] As downhole fluids are pumped into a production tank, the fluid may separate into different layers, such as sand, water, emulsion, oil, foam, and gas. The composition of the produced fluids will vary depending on the particular producing well.

SUMMARY

[0004] There is provided a foam level sensor for a production tank containing foam, comprising a sensor element that is supported by the surface tension of the foam, and a sensor switch that is triggered upon the sensor element being raised to a predetermined height.

[0005] According to another aspect, the sensor element may have a specific gravity of less than 0.45.

[0006] According to another aspect, the sensor element may be mounted on a sensor line, and the sensor element may be supported on the sensor line by a stopper until the foam level reaches the height of the stopper.

[0007] According to another aspect, the sensor element may mounted to an arm.

[0008] According to another aspect, the sensor element may comprise a flat bottom surface.

[0009] According to another aspect, there is provided a production tank containing fluid having a layer of foam in combination with a foam level sensor as described above.

[0010] According to another aspect, there is provided a method of operating a wellhead, comprising the steps of providing the combination described above; raising the level of foam in the production tank by pumping production fluids into the production tank such that the sensor element is raised; and triggering the sensor switch to trigger an event.

[0011] According to another aspect, the triggered event is one of a defoaming action and an alarm.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:
FIG. 1 is a side elevation view in section of a foam level sensor installed in a production tank.
FIG. 2 is a side elevation view in section of an alternative foam level sensor in stalled in a production tank.

DETAILED DESCRIPTION

[0013] A foam level sensor generally identified by reference numeral 10, will now be described with reference to FIG. 1 and 2.

[0014] Referring to FIG. 1, there is provided a production tank 12 that has layers of sand 14, water 16, oil 18 and foam 20. As production fluid is pumped into production tank 12 through inlet 22, it will separate into the various layers, based on their specific gravity, with foam on the top.

[0015] In order to efficiently empty the production tank of the various layers of material, it is necessary to know the levels. One type of sensor arrangement that measures the level of water 16 and oil 18 in tank 12 is depicted in FIG. 1 and 2, although it will be understood that other arrangements may be used. As depicted, a sensor line 24 has floats 26 and 28 that move along sensor line 24. Float 26 is designed to float on water but sink in oil, while float 28 is designed to float in oil. Sensor line 24 may determine the position of floats 26 and 28 by reed switches, or by other means.

[0016] Sensor line 24 is preferred, as it can be adapted to include foam level sensor 10, such that the same system can be used to measure each levels in tank 12.
Sensor 10 includes a sensor element 30 that is designed to be supported by the surface tension of the foam. This includes a proper design of the bottom surface that minimizes breaking the foam, and is also sufficiently light. For example, sensor element 30 may have a smooth, flat bottom surface and be made from a plastic foam that has a specific gravity of 0.45 or less.
Other materials known in the art may also be used. Sensor element 30 is connected to a sensor switch 32 that is triggered upon sensor element 30 being raised to a predetermined height. In the depicted embodiment, sensor switch 32 is contained within sensor line 24. Sensor switch 32 then triggers an event, such as by sending a signal to a controller 33. The event may be an alarm that is triggered, such as an audio or visual alarm on site, or a signal that is transmitted to a remote location using, for example, a SCADA system. Alternatively, sensor switch 32 may generate a signal that activates or deactivates equipment, for example, the well pump may be shut down, or a defoaming device, such as a sprayer that sprays a defoaming agent in tank 12, may be activated.

[0017] Sensor element 30 may be suspended at a specific height, such as by a stopper 34, such that it is not carried upward by foam layer 20 until it gets close to the predetermined height. Thus, instead of acting as a continuous level sensor in the sense of floats 26 and 28, sensor 10 acts more like a discrete level sensor, where the output relates only to whether that level has been reached or not. It will be understood that sensor element 30 may be designed to be carried continuously by foam layer 20, however to reduce the possibility of the surface tension breaking, which would prevent sensor element 30 from indicating when the level has been reached, it is preferred that sensor element 30 be suspended as depicted.
Sensor element may also act as a high level sensor that is triggered once the fluid level reaches that height, 25 even if no foam is present in the tank.

[0018] It will be understood that there are different ways in which sensor 10 may be deployed. As described above, sensor element 30 is mounted on a sensor line 24 with floats 24 and 26. However, sensor element 30 may be deployed on a separate line 24, or may not be 30 deployed on a line. Referring to FIG. 2, an alternative embodiment is shown, where sensor element 30 is mounted to the end of an arm 36.

[0019] In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.

[0020] The following claims are to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, and what can be obviously substituted. Those skilled in the art will appreciate that various adaptations and modifications of the described embodiments can be configured without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be taken as limiting the invention. It is to be understood that, within the scope of the following claims, the invention may be practiced other than as specifically illustrated and described.

Claims

1. A foam level sensor for a production tank containing foam, comprising:
a sensor element that is supported by the surface tension of the foam; and a sensor switch that is triggered upon the sensor element being raised to a predetermined height.

2. The foam level sensor of claim 1, wherein the sensor element has a specific gravity of less than 0.45.

3. The foam level sensor of claim 1, wherein the sensor element is mounted on a sensor line.

4. The foam level sensor of claim 3, wherein the sensor element is supported on the sensor line by a stopper until the foam level reaches the height of the stopper.

5. The foam level sensor of claim 1, wherein the sensor element is mounted to an arm.

6. The foam level sensor of claim 1, wherein the sensor element comprises a flat bottom surface.

7. In combination:
a production tank containing fluid having a layer of foam; and a foam level sensor for a production tank, the foam level sensor comprising:
a sensor element that is supported by the surface tension of the foam; and a sensor switch that is triggered upon the sensor element being raised to a predetermined height, the sensor switch triggering an event.

8. The combination of claim 7, wherein the event is an alarm.

9. The combination of claim 7, wherein the event is a signal to shut down a well pump.

10. The combination of claim 7, wherein the event is a signal to activate a defoaming device.

11. The combination of claim 7, wherein the sensor element has a specific gravity of less than 0.45.

12. The combination of claim 7, wherein the sensor element is mounted on a sensor line.

13. The combination of claim 12, wherein the sensor element is supported on the sensor line by a stopper until the foam level reaches the height of the stopper.

14. The combination of claim 7, wherein the sensor element is mounted to an arm.

15. The combination of claim 7, wherein the sensor element comprises a flat bottom surface.

16. A method of operating a wellhead, comprising the steps of:
providing:
a production tank, the production tank containing fluid having a layer of foam;
a sensor element that is supported by the surface tension of the foam; and a sensor switch that is triggered upon the sensor element being raised to a predetermined height;
raising the level of foam in the production tank by pumping production fluids into the production tank such that the sensor element is raised;
triggering the sensor switch to trigger an event.

17. The method of claim 16, wherein the event is an alarm.

18. The method of claim 16, wherein the event is a signal to shut down a well pump.

19. The method of claim 16, wherein the event is a signal to activate a defoaming device.

20. The method of claim 16, wherein the sensor element has a specific gravity of less than 0.45.

21. The method of claim 16, wherein the sensor element is mounted on a sensor line.

22. The method of claim 21, wherein the sensor element is supported on the sensor line by a stopper until the foam level reaches the height of the stopper.

23. The method of claim 16, wherein the sensor element is mounted to an arm.

24. The method of claim 16, wherein the sensor element comprises a flat bottom surface.

25. The method of claim 16, wherein the event is one of a defoaming action and an alarm.