Shifting tool and associated methods for operating downhole valves
A shifting tool can include a flow restrictor outwardly extendable in a well. A method can include flowing a fluid through a flow restriction, thereby creating a pressure differential and, in response, shifting a closure member while the fluid flows through the flow restriction. Another method can include positioning a shifting tool in a tubular string, then outwardly extending keys from the shifting tool in response to fluid pressure applied to the shifting tool, then engaging the keys with a profile formed in a closure member, and then shifting the closure member between open and closed positions.
1. A method of operating at least one downhole valve connected in a tubular string in a subterranean well, the method comprising:
radially outwardly expanding a flow restrictor in response to longitudinal compression of the flow restrictor, thereby forming an annular flow restriction without preventing flow between the flow restrictor and a closure member, in which the flow restrictor comprises at least one ring;
flowing a fluid through the flow restriction, thereby creating a pressure differential across the flow restriction; and
the pressure differential producing a longitudinally directed force which acts to shift the closure member of the downhole valve between open and closed positions.
2. The method of claim 1 , further comprising forming the flow restriction radially between a shifting tool and the downhole valve.
3. The method of claim 1 , further comprising forming the flow restriction radially between a shifting tool and the closure member.
4. The method of claim 1 , further comprising engaging a shifting tool with a profile formed in the closure member.
5. The method of claim 4 , in which the shifting tool is engaged with the closure member profile while the fluid flows through the flow restriction.
6. The method of claim 1 , further comprising positioning a shifting tool in the downhole valve, and displacing the flow restrictor radially outward from the shifting tool.
7. The method of claim 6 , in which the flow restrictor displaces radially outward in response to axial compression of the shifting tool downhole.
8. The method of claim 6 , in which the flow restrictor displacing comprises reducing an annular flow area between the shifting tool and the downhole valve.
9. The method of claim 6 , in which the flow restrictor displaces radially outward after the shifting tool is engaged with the closure member.
10. The method of claim 6 , further comprising displacing the flow restrictor radially inward after the flow restrictor is displaced radially outward.
11. The method of claim 1 , further comprising outwardly extending keys from a shifting tool downhole, in response to fluid pressure applied to the shifting tool, and then engaging the keys with a profile formed in the closure member.
12. The method of claim 1 , in which the closure member shifting comprises shifting the closure member to the open position, and in which the method further comprises then shifting the closure member to the closed position.