Downhole safety valve

Claim 2

A safety valve for shutting in a well responsive to flow of well fluid exceeding a predetermined rate; comprising: a valve body having an orifice communicating with the well fluid; a seat within said valve body downstream of said orifice; a plug extending through said seat, said plug being axially movable through said seat between a first position defining an annular port in combination with said seat and a second position in contact with said seat to shut in the well; means resiliently urging said plug toward the first position to maintain said valve open when the flow of well fluid is at a rate not more than the predetermined rate; and means moving said plug to the second position responsive to flow of well fluid exceeding the predetermined rate to shut in the well.

Claim 3

A safety valve as recited in claim 1, including means for variably adjusting the area of the annular port between said seat and said plug when said plug is in the first position.

Claim 4

A safety valve as recited in claim 1, wherein said seat and said plug define mating tapered surfaces.

Claim 5

A safety valve as recited in claim 3, wherein said seat and said plug have first mating tapered surfaces toward their respective downstream ends and second mating tapered surfaces upstream from said first surfaces and intersecting said first surfaces at an angle with respect thereto to define annular seating surfaces for preventing flow between said plug and said seat when said plug is in the second position.

Claim 6

A safety valve as recited in claim 1, wherein said urging means is adjustable to selectively preestablish the flow rate above which the valve operates to shut in the well.

Claim 7

A safety valve as recited in claim 1, wherein said urging means comprises a compressed spring.

Claim 8

A safety valve as recited in claim 1, wherein said seat and Said plug comprise sintered tungsten carbide.

Claim 9

A safety valve as recited in claim 1, wherein said valve is wireline retrievable.

Claim 10

A downhole safety valve for insertion into a well flowing an abrasive well fluid to shut in the well in response to a flow of well fluid exceeding a predetermined rate, comprising: a valve body having a plurality of orifices communicating with the well fluid; a tapered seat in said valve body downstream of said orifices; a plug extending through said seat and having a taper corresponding to the taper of said seat, said plug being axially movable through said seat between a first position defining an annular port between said seat and said plug and a second position in sealing engagement with said seat to shut in the well, said plug being exposed to a pressure differential responsive to flow of well fluid through said annular port, the pressure differential urging said plug toward said seat; and spring means for preventing movement of said plug from the first position to the second position responsive to the pressure differential produced by a well fluid flow rate not greater than the predetermined rate, and permitting said plug to move from the first position to the second position responsive to the pressure differential produced by a well fluid flow rate exceeding the predetermined rate to shut in the well.

Claim 11

A downhole safety valve for insertion into a well flowing an abrasive well fluid to shut in the well in response to a flow of well fluid exceeding a predetermined rate, comprising: a valve body having a plurality of orifices communicating with the well fluid; a tapered seat in said valve body downstream of said orifices; a plug extending through said seat and having a taper corresponding to the taper of said seat, said plug being axially movable through said seat between a first position defining an annular port between said seat and said plug and a second position in sealing engagement with said seat to shut in the well, said plug being exposed to a pressure differential responsive to flow of well fluid through said annular port, the pressure differential urging said plug toward said seat; and spring means for preventing movement of said plug from the first position to the second position responsive to the pressure differential produced by a well fluid flow rate not greater than the predetermined rate, and permitting said plug to move from the first position to the second position responsive to the pressure differential produced by a well fluid flow rate exceeding the predetermined rate to shut in the well.

Claim 12

A downhole safety valve as recited in claim 9, including means for variably adjusting the area of the annular port defined by the first position of said seat and said plug.

Claim 13

A downhole safety valve as recited in claim 9, including means for variably adjusting the force of said spring means to predetermine the pressure differential required to move said plug to the second position.

Claim 14

A downhole safety valve as recited in claim 9, wherein said seat and said plug comprise sintered tungsten carbide.

Claim 15

A downhole safety valve as recited in claim 9, wherein said seat and said plug include first mating tapered surfaces on their respective downstream ends and second mating tapered surfaces upstream from said first surfaces and intersecting said first surfaces at an angle.

Claim 16

A downhole safety valve as recited in claim 13, wherein the angle of said first taper with respect to the axis of said plug is less than the angle of said second taper with respect to said axis.

Claim 17

A downhole safety valve as recited in claim 13, wherein the angle of said first taper with respect to the axis of said plug is about 8* and the angle of said second taper with respect to the axis of said plug is about 45*.

Claim 18

An abrasion-resistant, adjustable downhole safety valve for wireline insertion into and retrieval from a well flowing an abrasive fluid for shutting in the well in response to a flow of well fluid exceeding a predetermined rate, comprising: a valve body having an interior communicating with the well fluid and having a tapered seat; a plug extending through said seat and having a corresponding taper, said plug being axially movable between a first position defining an annular port between said seat and said plug and a second position in contact with said seat to shut in the well, said plug being exposed to a pressure differential increasing with flow rate to urge said plug toward said second position to shut in the well; a stem extending axially upstream from said plug; a coiled spring coaxially surrounding said stem and having a first end abutting a spring retaining means at a location fixed with respect to said valve body and a second end abutting means variably connected to said stem for adjustably predetermining the force urging said plug toward the first position, said spring force being adjusted to be greater than the pressure differential force responsive to flow rates less than the predetermined rate to maintain said plug in the first position and less than the pressure differential responsive to the predetermined flow rate to permit the pressure diffErential responsive to the predetermined flow rate to move said plug to the second position to shut in the well; and a stop adjustably located with respect to said seat for limiting the upstream travel of said stem responsive to said spring to predetermine the cross-sectional area of the annular port when said plug is in the first position.

Claim 19

An abrasion-resistant, adjustable downhole safety valve for wireline insertion into and retrieval from a well flowing an abrasive fluid for shutting in the well in response to a flow of well fluid exceeding a predetermined rate, comprising: a valve body having an interior communicating with the well fluid and having a tapered seat; a plug extending through said seat and having a corresponding taper, said plug being axially movable between a first position defining an annular port between said seat and said plug and a second position in contact with said seat to shut in the well, said plug being exposed to a pressure differential increasing with flow rate to urge said plug toward said second position to shut in the well; a stem extending axially upstream from said plug; a coiled spring coaxially surrounding said stem and having a first end abutting a spring retaining means at a location fixed with respect to said valve body and a second end abutting means variably connected to said stem for adjustably predetermining the force urging said plug toward the first position, said spring force being adjusted to be greater than the pressure differential force responsive to flow rates less than the predetermined rate to maintain said plug in the first position and less than the pressure differential responsive to the predetermined flow rate to permit the pressure diffErential responsive to the predetermined flow rate to move said plug to the second position to shut in the well; and a stop adjustably located with respect to said seat for limiting the upstream travel of said stem responsive to said spring to predetermine the cross-sectional area of the annular port when said plug is in the first position.

Claim 20

A downhole safety valve as recited in claim 16, wherein said seat and said plug include first and second mating tapered surfaces, said second surfaces being upstream of said first surfaces and disposed at an angle of about 45* to the axis of said plug to define opposed annular seating surfaces for shutting in the well when said plug is in the second position.

Claim 21

A downhole safety valve as recited in claim 16, wherein said seat and said plug comprise sintered tungsten carbide.