Dual barrier injection valve
A wireline retrievable injection valve for an oil or gas well has an internal valve that is initially moved to open a flapper safety valve and also opens to allow fluid flow through the valve. The internal valve includes a sleeve that opens the flapper safety valve and shields the flapper safety valve from fluid. In this manner the flapper valve is protected from being caused to “flutter” or “chatter” due to pressure variations in the fluid flow, which may damage the seat.
1. An injection valve comprising:
a) a valve body having an inlet and outlet;
b) a flapper valve element pivotally mounted in a lower portion of the valve body;
c) an axially movable variable orifice insert positioned within the valve body including a second valve, a stationary middle sleeve and an outer sleeve, and a pair of magnets of opposite polarity, one of said magnets being fixed on the middle sleeve and the other of said magnets being movable with the outer sleeve, and a preloaded spring positioned between the movable magnet and the stationary middle sleeve.
2. An injection valve according to claim 1 wherein the variable orifice insert includes an axially movable valve body and a fixed valve seat which together form a variable annular orifice.
3. An injection valve according to claim 2 wherein the axially movable valve body is moved by a pressure differential.
4. An injection valve according to claim 3 wherein the valve seat includes a diverging outlet.
5. An injection valve according to claim 2 wherein the axially movable valve body is secured within a flow passage formed within the variable orifice insert between an inlet and an outlet.
6. An injector valve as claimed in claim 1 wherein the outer sleeve is slideably mounted on the stationary middle sleeve.
7. An injection valve as claimed in claim 6 wherein the variable orifice insert includes a valve seat positioned on an interior surface of the middle sleeve and an annular orifice between the axially movable valve body and the valve seat when the axially movable valve body moves in an axial direction.
8. An injector valve as claimed in claim 1 wherein the variable orifice insert includes an axially movable valve body attached to the outer sleeve.
9. An injection valve as claimed in claim 1 further including an outer sleeve having a J slot, and a pin fixed to the middle sleeve and positioned within the J slot of the outer sleeve.
10. A variable orifice insert comprising:
a) a valve,
b) a housing including a stationary middle sleeve,
c) an outer sleeve axially movable over the middle sleeve,
d) a pair of magnets of opposite polarity, one of said magnets being fixed with respect to the middle sleeve and the other of said magnets being movable with the outer sleeve, and
e) a preloaded spring positioned between the movable magnet and the middle sleeve.
11. A variable orifice insert according to claim 10 wherein the outer sleeve includes a lower portion and an axially movable valve body on the lower portion, and a fixed valve seat which together with the axially movable valve body form a variable annular orifice.
12. The variable orifice insert as claimed in claim 11 wherein the fixed valve seat is formed at the downstream end of the middle sleeve.
13. The variable orifice insert of claim 10 wherein the preloaded spring abuts against the movable magnet at one end of the spring and abuts against a shoulder provided on the middle sleeve at a second end of the spring.