Variable rate hydraulic-pneumatic weight control and compensating apparatus

Claim 2

In apparatus for maintaining a predetermined stress in a running string: cylinder means; piston means slidable in said cylinder means; one of said means being adapted for operative connection to the running string; the other of said means being adapted for operative connection to a support; means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions; said pressure maintaining means comprising container means containing a gaseous medium, said container means being separate from said cylinder means; and means for changing the effective volume of said container means and of the gaseous medium therein effective for operation upon said liquid medium at a given unit pressure to vary the spring rate of said gaseous medium.

Claim 3

In apparatus for maintaining a predetermined stress in a running string: cylinder means; piston means slidable in said cylinder means; one of said means being adapted for operative connection to the running string; the other of said means being adapted for operative connection to a support; means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions; said pressure maintaining means comprising a gaseous medium under pressure exerting its pressure force on said liquid medium; and means for varying the volume of said gaseous medium at the same unit pressure effecTive for exerting its pressure force on said liquid medium; said pressure maintaining means further including an accumulator cylinder containing part of said liquid medium in one portion thereof and said gaseous medium in another portion thereof for transmitting its pressure to said liquid medium; said volume varying means comprising a plurality of gaseous medium containers connected to the gaseous medium portion of said accumulator cylinder, and means for communicating said accumulator cylinder with different numbers of said containers to selectively determine the spring rate of said gaseous medium by permitting gas to flow simultaneously and in both directions between the selected number of containers and said accumulator cylinder.

Claim 4

In apparatus for maintaining a predetermined stress in a running string: cylinder means; piston means slidable in said cylinder means; one of said means being adapted for operative connection to the running string; the other of said means being adapted for operative connection to a support; means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions; said pressure maintaining means comprising a gaseous medium under pressure exerting its pressure force on said liquid medium; and means for varying the volume of said gaseous medium at the same unit pressure effecTive for exerting its pressure force on said liquid medium; said pressure maintaining means further including an accumulator cylinder containing part of said liquid medium in one portion thereof and said gaseous medium in another portion thereof for transmitting its pressure to said liquid medium; said volume varying means comprising a plurality of gaseous medium containers connected to the gaseous medium portion of said accumulator cylinder, and means for communicating said accumulator cylinder with different numbers of said containers to selectively determine the spring rate of said gaseous medium by permitting gas to flow simultaneously and in both directions between the selected number of containers and said accumulator cylinder.

Claim 5

In apparatus as defined in claim 2; said communicating means including valve means for selectively permitting or preventing flow of said gaseous medium between some of said containers and said accumulator cylinder.

Claim 6

In apparatus as defined in claim 2; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; and valve means in said conduit means for controlling flow of said gaseous medium through said conduit means.

Claim 7

In apparatus as defined in claim 2; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; and valve means in said conduit means for controlling flow of said gaseous medium through said conduit means, said valve means being operable to selectively effect increase or decrease in pressure of said gaseous medium in said accumulator cylinder and containers.

Claim 8

In apparatus as defined in claim 2; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; and valve means in said conduit means for controlling flow of said gaseous medium through said conduit means, said conduit means including a first tubular line for conducting said gaseous medium between said source and some of said containers and a second tubular line for conducting said gaseous medium between said source and other of said containers and said accumulator cylinder; said valve means including valves in said first and second tubular lines for individually controlling flow of said gaseous medium in said tubular lines.

Claim 9

In apparatus as defined in claim 2; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; and valve means in said conduit means for controlling flow of said gaseous medium through said conduit means, said valve means being operable to selectively effect increase or decrease in pressure of said gaseous medium in said accumulator cylinder and containers, said conduit means including a first tubular line for conducting said gaseous medium between said source and some of said containers and a second tubular line for conducting said gaseous medium between said source and other of said containers and said accumulator cylinder; said valve means including valves in said first and second tubular lines for selectively effecting increase or decrease in the pressure of the gaseous medium in said some of said containers and said other of said containers and accumulator cylinder.

Claim 10

In apparatus as defined in claim 2; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; and valve means in said conduit means for controlling flow of said gaseous medium through said conduit means, said conduit means including a first tubular line for conducting said gaseous medium between said source and some of said containers and a second tubular line for conducting said gaseous medium between said source and other of said contAiners and said accumulator cylinder; said valve means including valves in said first and second tubular lines for individually controlling flow of said gaseous medium in said tubular lines; and means including an isolation valve selectively preventing or permitting communication between said some of said containers and said other of said containers.

Claim 11

In apparatus as defined in claim 2; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; and valve means in said conduit means for controlling flow of said gaseous medium through said conduit means, said valve means being operable to selectively effect increase or decrease in pressure of said gaseous medium in said accumulator cylinder and containers, said conduit means including a first tubular line for conducting said gaseous medium between said source and some of said containers and a second tubular line for conducting said gaseous medium between said source and other of said containers and said accumulator cylinder; said valve means including valves in said first and second tubular lines for selectively effecting increase or decrease in the pressure of the gaseous medium in said some of said containers and said other of said containers and accumulator cylinder; and means including an isolation valve selectively preventing or permitting communication between said some of said containers and said other of said containers.

Claim 12

In apparatus for maintaining a predetermined stress in a running string disposed in a well bore and which is supported by a rig: elongate cylinder means; piston means slidable in said cylinder means; one of said means being adapted for operative connection to the running string; the other of said means being adapted for operative connection to the rig; means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions; said pressure maintaining means comprising container means containing a gaseous medium under pressure exerting its pressure force on said liquid medium, said container means being separate from said cylinder means; and means for changing the effective volume of said container means and of the gaseous medium therein effective for operation upon said liquid medium at a given unit pressure to vary the spring rate of said gaseous medium.

Claim 13

In apparatus for maintaining a predetermined stress in a running string disposed in a well bore and which is supported by a rig: elongate cylinder means; piston means slidable in said cylinder means; one of said means being adapted for operative connection to the running string; the other of said means being adapted for operative connection to the rig; means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions; said pressure maintaining means comprising container means containing a gaseous medium under pressure exerting its pressure force on said liquid medium, said container means being separate from said cylinder means; and means for changing the effective volume of said container means and of the gaseous medium therein effective for operation upon said liquid medium at a given unit pressure to vary the spring rate of said gaseous medium.

Claim 14

In apparatus for maintaining a predetermined stress in a running string disposed in a well bore and which is supported by a rig: elongate cylinder means; piston means slidable in said cylinder means; one of said means being adapted for operative connection to the running string; the other of said means being adapted for operative connection to the rig; means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions; said pressure maintaining means comprising a gaseous medium under pressure exerting its pressure force on said liquid medium; and means for varying the volume of said gaseous medium at the same unit pressure effective for exerting its pressure force on said liquid medium; said pressure maintaining means further including an accumulator cylinder containing part of said liquid medium in one portion thereof and said gaseous medium in another portion thereof for transmitting its pressure to said liquid medium; said volume varying means comprising a plurality of gaseous medium containers connected to the gaseous medium portion of said accumulator cylinder, and means for connumicating said accumulator cylinder with different numbers of said containers to selectively determine the spring rate of said gaseous medium.

Claim 15

In apparatus for maintaining a predetermined stress in a running string disposed in a well bore and which is supported by a rig: elongate cylinder means; piston means slidable in said cylinder means; one of said means being adapted for operative connection to the running string; the other of said means being adapted for operative connection to the rig; means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions; said pressure maintaining means comprising a gaseous medium under pressure exerting its pressure force on said liquid medium; and means for varying the volume of said gaseous medium at the same unit pressure effective for exerting its pressure force on said liquid medium; said pressure maintaining means further including an accumulator cylinder containing part of said liquid medium in one portion thereof and said gaseous medium in another portion thereof for transmitting its pressure to said liquid medium; said volume varying means comprising a plurality of gaseous medium containers connected to the gaseous medium portion of said accumulator cylinder, and means for connumicating said accumulator cylinder with different numbers of said containers to selectively determine the spring rate of said gaseous medium.

Claim 16

In apparatus as defined in claim 11; said communicating means including valve means for sElectively permitting or preventing flow of said gaseous medium between some of said containers and said accumulator cylinder.

Claim 17

In apparatus as defined in claim 11; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; and valve means in said conduit means for controlling flow of said gaseous medium through said conduit means.

Claim 18

In apparatus as defined in claim 11; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; and valve means in said conduit means for controlling flow of said gaseous medium through said conduit means, said conduit means including a first tubular line for conducting said gaseous medium between said source and some of said containers and a second tubular line for conducting said gaseous medium between said source and other of said containers and said accumulator cylinder; said valve means including valves in said first and second tubular lines for individually controlling flow of said gaseous medium in said tubular lines.

Claim 19

In apparatus as defined in claim 11; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; and valve means in said conduit means for controlling flow of said gaseous medium through said conduit means, said conduit means including a first tubular line for conducting said gaseous medium between said source and some of said containers and a second tubular line for conducting said gaseous medium between said source and other of said containers and said accumulator cylinder; said valve means including valves in said first and second tubular lines for individually controlling flow of said gaseous medium in said tubular lines; and means including an isolation valve selectively preventing or permitting communication between said some of said containers and said other of said containers.

Claim 20

In apparatus for maintaining a predetermined stress in a running string disposed in a well bore and which is supported by a rig including a suspension mechanism: elongate cylinder means; piston means slidable in said cylinder means; one of said means having a device thereon for operative connection to the running string; the other of said means having a device thereon for operative connection to the suspension mechanism, whereby said cylinder means and piston means are disposed between the suspension mechanism and running string; means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions, whereby the stress of the running string and of said one means is transmitted through the liquid to said other means and suspension mechanism; said pressure maintaining means comprising container means containing a gaseous medium under pressure exerting its pressure force on said liquid medium; said pressure maintaining means further including an accumulator cylinder communicating with said container means and containing part of said liquid medium in one portion thereof and said gaseous medium in another portion thereof for transmitting its pressure to said liquid medium; said container means being separate from said accumulator cylinder; and means for changing the effective volume of said container means and of the gaseous medium therein effective for operation upon said liquid medium at a given unit pressure to vary the spring rate of said gaseous medium.

Claim 21

In apparatus for maintaining a predetermined stress in a running string disposed in a well bore and which is supported by a rig including a suspension mechanism: elongate cylinder means; piston means slidable in said cylinder means; one of said means having a device thereon for operative connection to the running string; the other of said means having a device thereon for operative connection to the suspension mechanism, whereby said cylinder means and piston means are disposed between the suspension mechanism and running string; means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions, whereby the stress of the running string and of said one means is transmitted through the liquid to said other means and suspension mechanism; said pressure maintaining means comprising container means containing a gaseous medium under pressure exerting its pressure force on said liquid medium; said pressure maintaining means further including an accumulator cylinder communicating with said container means and containing part of said liquid medium in one portion thereof and said gaseous medium in another portion thereof for transmitting its pressure to said liquid medium; said container means being separate from said accumulator cylinder; and means for changing the effective volume of said container means and of the gaseous medium therein effective for operation upon said liquid medium at a given unit pressure to vary the spring rate of said gaseous medium.

Claim 22

In apparatus for maintaining a predetermined stress in a running string disposed in a well bore and which is supported by a rig including a suspension mechanism: elongate cylinder means; piston means slidable in said cylinder menas; one of said means having a device thereon for operative connection to the running string; the other of said means having a device thereon for operative connection to the suspension mechanism, whereby said cylinder means and piston means are disposed between the suspension mechanism and running string: means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions, whereby the stress of the running string and of said one means is transmitted through the liquid to said other means and suspension mechanism; said pressure maintaining means comprising a gaseous medium under pressure exerting its pressure force on said liquid medium; said pressure maintaining means further including an accumulator cylinder containing part of said liquid medium in one portion thereof and said gaseous medium in another portion thereof for transmitting its pressure to said liquid means; and means for varying the volume of said gaseous medium at the same unit pressure effective for exerting its pressure force on said liquid medium; said volume varying means comprising a plurality of gaseous medium containers connected to the gaseous medium portion of said accumulator cylinder, and means for communicating said accumulator cylinder with different numbers of said containers to selectively determine the spring rate of said gaseous medium by permitting gas to flow simultaneously and in both directions between the selected number of containers and said accumulator cylinder.

Claim 23

In apparatus for maintaining a predetermined stress in a running string disposed in a well bore and which is supported by a rig including a suspension mechanism: elongate cylinder means; piston means slidable in said cylinder menas; one of said means having a device thereon for operative connection to the running string; the other of said means having a device thereon for operative connection to the suspension mechanism, whereby said cylinder means and piston means are disposed between the suspension mechanism and running string: means for maintaining a liquid medium under pressure in said cylinder means on one side of said piston means as said piston means and cylinder means move longitudinally relative to one another in both longitudinal directions, whereby the stress of the running string and of said one means is transmitted through the liquid to said other means and suspension mechanism; said pressure maintaining means comprising a gaseous medium under pressure exerting its pressure force on said liquid medium; said pressure maintaining means further including an accumulator cylinder containing part of said liquid medium in one portion thereof and said gaseous medium in another portion thereof for transmitting its pressure to said liquid means; and means for varying the volume of said gaseous medium at the same unit pressure effective for exerting its pressure force on said liquid medium; said volume varying means comprising a plurality of gaseous medium containers connected to the gaseous medium portion of said accumulator cylinder, and means for communicating said accumulator cylinder with different numbers of said containers to selectively determine the spring rate of said gaseous medium by permitting gas to flow simultaneously and in both directions between the selected number of containers and said accumulator cylinder.

Claim 24

In apparatus as defined in claim 17; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; valve means in said conduit means for controlling flow of said gaseous medium through said conduit means; said conduit means including a first tubular line for conducting said gaseous medium between said source and some of said containers and a second tubular line for conducting said gaseous medium between said source and other of said containers and said accumulator cylinder; said valve means including valves in said first and second tubular lines for individually controlling flow of said gaseous medium in said tubular lines.

Claim 25

In apparatus as defined in claim 17; a source of said gaseous medium under pressure; conduit means for conducting said gaseous medium from said source to said accumulator cylinder and said containers; valve means in said conduit means for controlling flow of said gaseous medium through said conduit means; said conduit means including a first tubular line for conducting said gaseous medium between said source and some of said containers and a second tubular line for conducting said gaseous medium between said source and other of said containers and said accumulator cylinder; said valve means including valves in said first and second tubular lines for individually controlling flow of said gaseous medium in said tubular lines; and means including an isolation valve selectively preventing or permitting communication between said some of said containers and said other of said containers.