Dual check valve
A check valve comprising a section of a drill string, a flapper valve positioned within and concentric to the section of the drill string, and a piston valve positioned within and concentric to the section of the drill string. The flapper valve allows fluid flow in a first direction through an inner portion of a cross-section of the section of the drill string and not allowing fluid flow in a second direction, and the piston check valve allowing fluid flow in the first direction through an outer portion of the cross-section of the section of the drill string and not allowing fluid flow in the second direction, where the first portion and the second portion of the cross-section of the section of the drill string are mutually exclusive.
A check valve is designed to open under certain pressure conditions, and close under others. Check valves are often used in tubing stings for applications such as drilling, fishing, and completing bottom hole assemblies to prevent hydrocarbons or unwanted fluids from flowing back up the tubing string. Examples of these types of valves are models “FC”, “F”, “GC” and “G” drill pipe float valves produced by Bakerline of San Antonio, Tex. A disadvantage with these check valves is that they limit flow through them for a given pressure. Under some circumstances, this could result in a downhole motor stalling.
SUMMARYThere is provided a check valve that allows increased flow through the valve, comprising a housing, such as a section of a drill string, a first check valve, and a second check valve. The first check valve and second check valve are oriented to provide flow paths in parallel, either in the same direction or in opposed directions. The second check valve is at least partly within the first check valve. The first check valve is positioned within the housing and in one embodiment may be concentric to the housing. The second check valve is positioned within and in one embodiment may be concentric to the housing and in some embodiments may be wholly within the first check valve. In some embodiments, each of the first check valve and the second check valve may be selected from a group consisting of a flapper valve, a piston valve, a ball valve or a poppet valve. One or both the first check valve and the second check valve may be biased closed by for example a spring or fluid pressure and the housing may comprise a port to apply fluid pressure. Surfaces that redirect abrasive flows within the first and second check valves may be tapered surfaces.
In an embodiment, the second check valve is positioned within an inner wall of the housing, the second check valve having an annular shape, and the first check valve is positioned within the annular shape wall of the second check valve.
In another embodiment, the first check valve opens to allow fluid flow in the first direction when fluid pressure above a first threshold is applied, and the second valve opens to allow fluid flow in the first direction when a fluid pressure above a second threshold that is higher than the first threshold is applied.
There will now be given a brief description of a dual check valve, by reference to the drawings, by way of illustration only, and in which:
In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite article “a” before a claim feature does not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.
Referring to
First and second check valves 20 and 18 can be any suitable type of check valve, such as flapper valves, piston valves, ball valves, poppet valves, etc. In the embodiment depicted in
Referring to
Referring to
Variations of the above embodiment include varying the components that are stationary and the components that reciprocate components. For example, the upper piston 22 may reciprocate with the lower piston 38 being stationary, and second check valve 18 may reciprocate or be held stationary. The check valve may be used in any application where a check valve can be used, as for example in oilfield applications.
In addition, referring to
Check valve 10 is assembled by inserting the lower piston 38 with the spring 44 as shown in
Immaterial modifications may be made to the embodiments described here without departing from what is defined by the claims.
Claims
1. A check valve comprising:
- a housing;
- a first check valve positioned within the housing; and
- a second check valve positioned within the housing, the second check valve being positioned in parallel to and at least partly within the first check valve.
2. The check valve of claim 1 in which the first check valve and the second check valve are each oriented to block flow in a first direction and allow flow in a second direction opposite to the first direction.
3. The check valve of claim 1 in which the first check valve has a first flow path and the second check valve has a second flow path, and the second check valve is oriented so that the second flow path is wholly contained within the first flow path.
4. The check valve of claim 2, wherein each of the first check valve and the second check valve are selected from a group consisting of a flapper valve, a piston valve, a ball valve and a poppet valve.
5. The check valve of claim 2, wherein the first check valve is a flapper valve and the second check valve is a piston valve.
6. The check valve of claim 2, wherein the first check valve is configured to open when fluid pressure above a first threshold is applied, and the second check valve is configured to open when a fluid pressure above a second threshold that is higher than the first threshold is applied.
7. The check valve of claim 5, wherein the piston valve is biased closed by either a spring or fluid pressure within the piston chamber.
8. The check valve of claim 7, wherein the housing comprises a port to apply fluid pressure to the piston chamber.
9. The check valve of claim 2, wherein the housing comprises a section of a drill string.
10. The check valve of claim 2, wherein surfaces that redirect abrasive flows within the first and second check valves are tapered surfaces.
11. The check valve of claim 2, wherein the second check valve is positioned within an inner wall of the housing, the second check valve having an annular shape, and the first check valve is positioned within the annular shape wall of the second check valve.
12. The check valve of claim 2 in which the first check valve and the second check valve are each positioned concentric to the housing.
13. The check valve of claim 1 in which the first check valve and the second check valve are oriented to block flow in opposite directions, and one of the first check valve and the second check valve is biased to resist opening in the direction in which the other of the first check valve and the second check valve blocks flow.
14. The check valve of claim 13 in which the first check valve has a first flow path and the second check valve has a second flow path, and the second check valve is oriented so that the second flow path is wholly contained within the first flow path.
15. The check valve of claim 11, wherein each of the first check valve and the second check valve are selected from a group consisting of a flapper valve, a piston valve, a ball valve and a poppet valve.
16. A check valve comprising:
- a section of a drill string;
- a flapper valve positioned within the section of the drill string, the flapper valve allowing fluid flow in a first direction through an inner portion of a cross-section of the section of the drill string; and
- a piston valve positioned within the section of the drill string, the piston valve allowing fluid flow in the first direction through an outer portion of the cross-section of the section of the drill string, where the first portion and the second portion of the cross-section of the section of the drill string are mutually exclusive.
17. The check valve of claim 16 in which the flapper valve and the piston valve are each positioned concentric to the housing.
18. A check valve, comprising:
- a section of a drill string;
- a ball valve positioned within and concentric to the section of the drill string, the ball valve allowing fluid flow in a first direction through an inner portion of a cross-section of the section of the drill string; and
- a piston valve positioned within and concentric to the section of the drill string, the piston valve allowing fluid flow in a second direction opposed to the first direction through an outer portion of the cross-section of the section of the drill string and not allowing fluid flow in the second direction, where the first portion and the second portion of the cross-section of the section of the drill string are mutually exclusive.
Type: Application
Filed: Mar 19, 2007
Publication Date: Sep 20, 2007
Inventor: Gerald Leeb (Gwynne)
Application Number: 11/725,688
International Classification: E21B 34/00 (20060101);