초록 ▼

A flapper type downhole valve is opened by flow against the flapper. The flapper and the housing contain magnets that hold the flapper open after it has been opened by flow to keep the flapper from chattering from the flow going past it. The strength of the force is not sufficient to hold the flappe

A flapper type downhole valve is opened by flow against the flapper. The flapper and the housing contain magnets that hold the flapper open after it has been opened by flow to keep the flapper from chattering from the flow going past it. The strength of the force is not sufficient to hold the flapper open against a torsion spring on a pivot pin, when there is no flow through the valve. The valve can still be held in the locked open position with no flow through the housing by pressurizing the surrounding annulus to position another magnet to increase the holding force to a level greater than the force of the torsion spring. The additional magnet is spring biased so that upon removal of annulus pressure it shifts to allow the flapper to close. Alternative designs with and without a flow tube are possible. Fixed or movable restrictions can be associated with the flow tube to create a force to shift it to open a flapper with flow into the well.

대표청구항 ▼

We claim: 1. A downhole valve, comprising: a housing having a flow passage therethrough and a valve member movable between an open and a closed position with respect to a seat, said valve member biased toward said closed position by a first spring; selectively retaining said valve member in said op

We claim: 1. A downhole valve, comprising: a housing having a flow passage therethrough and a valve member movable between an open and a closed position with respect to a seat, said valve member biased toward said closed position by a first spring; selectively retaining said valve member in said open position against a tendency to chatter from said flow a lock assembly, movable in a wall of said housing adjacent the valve member, to lock said valve member in said open position when there is no flow, said assembly operating at least in part independently of said selectively retaining said valve member against chatter. 2. The valve of claim 1, further comprising: at least one housing magnet and at least one magnet on said valve member or intrinsically as at least a part of said valve member; whereupon flow through said passage forcing said valve member away from said seat brings said magnets closer such that the attraction between said magnets reduces the tendency of said valve member to chatter from said flow. 3. The valve of claim 2, wherein: said at least one housing magnet is movably mounted. 4. A downhole valve, comprising: a housing having a flow passage therethrough and a valve member movable between an open and a closed position with respect to a seat, said valve member biased toward said closed position by a first spring; selectively retaining said valve member in said open position against a tendency to chatter from said flow; at least one housing magnet and at least one magnet on said valve member or intrinsically as at least a part of said valve member; whereupon flow through said passage forcing said valve member away from said seat brings said magnets closer such that the attraction between said magnets reduces the tendency of said valve member to chatter from said flow; said at least one housing magnet is movably mounted; said housing comprises an exterior port leading to said at least one housing magnet so that pressure applied to said port moves said housing magnet toward said valve member magnet when said valve member is displaced from said seat. 5. The valve of claim 4, wherein: said valve member comprises a flapper that pivots on a pin that supports said first spring; said housing comprises a biasing member acting against said at least one housing magnet in opposition to force applied at said port; whereupon rotation of said flapper by flow though said passage said flapper magnet is rotated and is substantially aligned with said at least one housing magnet only when pressure at said port displaces said at least one housing magnet against said biasing member. 6. The valve of claim 5, wherein: said at least one housing magnet comprises a fixed magnet positioned in said housing to be in alignment with said flapper magnet when flow through said passage rotates said flapper away from said seat and a movable magnet selectively positioned into alignment with said fixed magnet. 7. The valve of claim 6, wherein: the attraction force between said flapper and said fixed magnet when brought toward each other is less than the force of said first spring on said flapper trying to move said flapper against said attraction force. 8. The valve of claim 7, wherein: said flapper stays open off its seat with said flapper magnet and said fixed magnet aligned only if flow of a predetermined quantity is passing through said passage. 9. The valve of claim 8, wherein: alignment of said movable magnet with said fixed magnet provides a sufficient attractive force for said flapper to hold it against the opposing force from said first spring, said first spring comprises a torsion spring with an associated dampener. 10. The valve of claim 4, wherein: said flapper is shaped or has a surface treatment in a manner that creates a net opening force from flow going past it in said passage. 11. A downhole valve, comprising: a housing having a flow passage therethrough and a flapper movable between an open and a closed position with respect to a seat by a flow tube, said flapper biased toward said closed position by a flapper spring; said flow tube is biased away from said flapper by a closure spring and further comprises a flow path therethrough that serves as a restriction to flow to allow flow through said flow path to overcome the force of said bias and move said flapper off said seat said housing further comprises at least one housing magnet to selectively hold said flow tube against the bias of said closure spring with said flapper off said seat. 12. The valve of claim 11, wherein: said flow tube comprises at least one flow tube magnet to selectively interact with said housing magnet to hold the flow tube against the bias of said closure spring with said flapper off said seat. 13. The valve of claim 12, wherein: said housing magnet is axially movable into alignment with said flow tube magnet when said flow tube is moved against the bias of said closure spring with said flapper off the seat. 14. The valve of claim 13, wherein: said housing comprises an exterior port to communicate pressure to said housing magnet to create said axial movement against a housing spring. 15. The valve of claim 11, wherein: said flow tube comprises at least one flow tube magnet to selectively interact with said housing magnet to hold the flow tube against the bias of said closure spring with said flapper off said seat; said flapper comprises a flapper magnet; said flow tube, when urged against said flapper and advancing to cover said flapper, positions said flow tube magnet in alignment with said flapper magnet to reduce flapper chatter from flow. 16. The valve of claim 11, wherein: said flow path has a uniform dimension over its length. 17. The valve of claim 11, wherein: said flow path has a fixed orifice therein. 18. The valve of claim 11, wherein: said flow path has a variable orifice therein. 19. A downhole valve, comprising: a housing having a flow passage therethrough and a flapper movable between an open and a closed position with respect to a seat by a flow tube, said flapper biased toward said closed position by a flapper spring; said flow tube is biased away from said flapper by a closure spring and further comprises a flow path therethrough that serves as a restriction to flow to allow flow through said flow path to overcome the force of said bias and move said flapper off said seat; said flow path has a variable orifice therein; said orifice is actuated to change size with magnetic force. 20. The valve of claim 19, wherein: said orifice comprises a plurality of movable members having a free end and at least a portion thereof comprising a member magnet; said housing comprises at least one housing magnet to selectively move said members by interaction with said member magnets to define an orifice with the free ends of said members. 21. The valve of claim 20, wherein: said movable members have a retracted position where they do not protrude into said flow path. 22. The valve of claim 20, wherein: said housing magnet is axially movable. 23. The valve of claim 22, wherein: said housing comprises an exterior port to communicate pressure to said housing magnet to move it axially against a bias force. 24. The valve of claim 23, wherein: said housing magnet when moved axially toward said member magnets repels said member magnets to form said orifice. 25. The valve of claim 23, wherein: said movable members are sprung toward forming said orifice; said housing magnet when moved axially toward said member magnets attracts said member magnets to retract them and enlarge said orifice.