USOO7428922B2
`
`(12) Unlted States Patent
`(10) Patent No.:
`US 7,428,922 B2
`
`Fripp et a].
`(45) Date of Patent:
`Sep. 30, 2008
`
`(54) VALVE AND POSITION CONTROL USING
`MAGNETORHEOLOGICAL FLUIDS
`
`(75)
`
`InVemOISI Michael FriPPa Carrollton, TX (US);
`Darren Bar10w,Mansfield,TX(US);
`Brandon SOIIeau, Dallas, TX (US)
`.
`_
`.
`.
`(73) A551gnee. Halllburton Energy Serv1ces, Houston,
`TX (US)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154 b b 465 d
`.
`( ) y
`ays
`
`(21) Appl. No.: 10/090,054
`
`(22)
`
`Filed:
`
`Mar. 1, 2002
`
`5,598,908 A *
`5,636,178 A
`5,787,052 A
`6,019,201 A *
`6,036,226 A *
`6,145,595 A
`6,219,301 B1
`6,257,356 B1
`
`................. 192/215
`
`2/1997 York et a1.
`6/1997 Ritter
`7/1998 Gardner et a1.
`188/2671
`2/2000 Gordaninejad et 31.
`3/2000 Brown et a1.
`................ 280/736
`11/2000 Burris, H
`4/2001 Moriarty
`7/2001 Wassell
`
`(Continued)
`FOREIGN PATENT DOCUMENTS
`
`EP
`
`1236862
`
`9/2002
`
`(65)
`
`Prior Publication Data
`
`US 2003/0166470 A1
`
`Sep. 4, 2003
`
`(Continued)
`
`OTHER PUBLICATIONS
`
`(51)
`
`Int. Cl.
`(2006.01)
`E213 43/1185
`(52) us. Cl.
`................................. 166/665; 251/129.06
`(58) Field of Classification Search ................ 166/665,
`166/666, 66.7, 135, 334.1; 137/909; 251/129.06,
`251/129.08
`See application file for complete search history.
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`12/1953 Winslow
`2,661,596 A
`1/1988 Meek
`4,718,494 A
`11/1988 Chin et a1.
`4,785,300 A
`5/1991 Hardt
`......................... 102/216
`5,012,740 A *
`8/1991 Feld
`5,040,155 A
`9/1991 Cochran
`5,048,611 A
`12/1991 Jeter
`5,073,877 A
`5/1992 Mumbyetal.
`5,115,415 A
`5,158,109 A * 10/1992 Hare, Sr. .................. 137/5143
`5,168,931 A
`12/1992 Caskey et a1.
`5,223,665 A
`6/1993 Burleson
`5,284,330 A
`2/1994 Carlson et a1.
`5,586,084 A
`12/1996 Barron et a1.
`
`Examination Report for UK application No. GB0303599.5.
`C
`.
`d
`( ommue )
`Primary Examinerilennifer H Gay
`AssistantExam/neriDaniel P Stephenson
`(74) Attorney, Agent, or FirmiMarlin R. Smith
`
`(57)
`
`ABSTRACT
`
`Magnetorheological fluids, which solidify in response to a
`magnetic field, offer the ability to simplify many ofthe valves
`and control systems used downhole in the search for and
`production of oil and gas. They lessen the need for moving
`parts, provide solid-state valves, and can provide a differen-
`tial movement of fluid through the valves by varying the
`strength of the magnetic field. Combinations of permanent
`and electro-magnets can improve safety by providing valves
`that fail, when power is lost, in either an open or closed
`position, depending on design. A number of examples are
`given.
`
`27 Claims, 14 Drawing Sheets
`
`FLUID
`
`
`
`MEGCO EX. 1014
`
`MEGCO Ex. 1014
`
`

`

`US 7,428,922 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`6,280,658
`6,421,298
`6,469,367
`6,514,001
`6,568,470
`6,619,388
`6,926,089
`2003/0019622
`
`B1
`B1
`B2
`B1 *
`B2
`B2
`B2
`A1
`
`8/2001
`7/2002
`10/2002
`2/2003
`5/2003
`9/2003
`8/2005
`1/2003
`
`Atarashi et a1.
`Beattie et a1.
`Kondo et a1.
`
`......... 403/109.1
`
`Yezersky et al.
`Goodson
`Dietz
`Goodson, Jr. et a1.
`Goodson, Jr. et a1.
`
`2/2003 Goodson, Jr.
`2003/0037921 A1
`FOREIGN PATENT DOCUMENTS
`2039567 A *
`8/1980
`2396178
`6/2004
`OTHER PUBLICATIONS
`
`GB
`GB
`
`Official Action for Norwegian application No. 20030685.
`British Search Report
`issued for GB Patent Application No.
`06048508 on Jul. 10, 2006 (5 pages).
`
`* cited by examiner
`
`MEGCO EX. 1014
`
`MEGCO Ex. 1014
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`

`

`U.S. Patent
`
`Sep. 30, 2008
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`US 7,428,922 B2
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`U.S. Patent
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`US 7,428,922 B2
`
`1
`VALVE AND POSITION CONTROL USING
`MAGNETORHEOLOGICAL FLUIDS
`
`TECHNICAL FIELD
`
`The present invention relates to the use of magnetorheo-
`logical fluids in downhole equipment to provide solid-state
`controls.
`
`BACKGROUND OF THE INVENTION
`
`Magnetorheological Fluids
`In the 1950s, it was discovered that fluids could be created
`whose resistance to flow were modifiable by subjecting them
`to a magnetic or electric field. This was disclosed in US. Pat.
`No. 2,661,596, which is hereby incorporated by reference,
`where the inventor also disclosed its use in a hydraulic device.
`Those fluids that are responsive to an electrical field are
`known as electrorheological fluids while those responsive to
`magnetic fields are magnetorheological. Of these two, mag-
`netorheological fluids have been the easier to work with, as
`their electrical counterparts are susceptible to performance-
`degrading contamination and require strong electric fields,
`which necessitate complicated, expensive high-voltage
`power supplies and complex control systems. In contrast,
`both permanent magnets and electromagnets are inexpensive
`and easy to produce, while the magnetorheological fluids are
`not as sensitive to contamination.
`
`Magnetorheological (MR) fluids can be formed by com-
`bining a low viscosity fluid, such as a type of oil, with mag-
`netic particles to form a slurry. The original patent used par-
`ticles of iron on the order of 0.1 to 5 microns, with the
`particles comprising 20% or more by volume of the fluid.
`More recent work in MR fluids can be found, for instance, in
`US. Pat. No. 6,280,658. When a magnetic field passes
`through the fluid, the magnetic particles align with the field,
`limiting movement ofthe liquid due to the arrangement ofthe
`iron particles. As the field increases, the MR fluid becomes
`increasingly solid, but when the field is removed, the fluid
`resumes its liquid state again. FIG. 1 is a graph ofthe flow rate
`of an exemplary MR fluid through 0.4 inch inner diameter
`tubing versus the strength of the magnetic field applied to the
`fluid. In each case, the flow rate goes to zero as the field
`increases. Magnetorheological fluids have been used in such
`areas as dampers, locks, brakes, and abrasive finishing and
`polishing, with over 100 patents issued that utilize these flu-
`ids. MR fluids can be obtained from the Lord Corporation of
`Cary, NC.
`Downhole Equipment
`Devices that are used in the development and production of
`hydrocarbon wells have a number ofconstraints to which they
`must adhere. They must be capable of handling the harsh
`environment to which they are subjected, be controllable
`from the surface, and be sized to fit within the small area of a
`borehole, yet the fact that they can be operating thousands of
`feet underground makes their reliability a high priority. Some
`of the problems encountered in drilling and production of
`hydrocarbons are as follows:
`1) It is imperative to reliably be able to trigger an event
`when desired, but not before. For instance, the firing of guns
`used to create openings through the casing into a formation
`must release enough energy to fracture through not only the
`casing, but also through damaged sections of the formation.
`Premature firing of the guns is both a safety issue (i.e., per-
`sonnel can be injured) and an economic issue (equipment can
`be damaged, openings made into undesired strata must be
`repaired or bypassed).
`
`10
`
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`2) Many pieces of equipment used downhole have valves
`that must be opened and closed. In other equipment, the
`relationship between two parts must be fixed at some points in
`time, yet moveable at others, such in a travel joint, which
`makes up for the movement of a drilling ship as it floats on the
`surface of the ocean. Traditional apparatus has relied various
`physical means to operate valves or release a part from a fixed
`relationship. These can include rotating the drill string to
`release a J-fastener, relying on pressure, either within the
`string or in the annulus, to rupture a valve or to apply the
`pressure necessary to move a part, and shear pins or similar
`devices. It is desirable to have more reliable means of oper-
`ating this equipment more precisely. Additionally, the use of
`moving parts leads to rigorous designs that have redress costs
`and require rig time to trigger the valves. It would be desirable
`to utilize solid-state valves to lower costs, improve reliability,
`and decrease rig time for activation.
`3) It would be desirable to provide a simple means for
`performing logical control steps, without the use of moving
`parts.
`4) Devices such as packers traditionally use hard rubber
`parts to seal between the downhole tubing and the casing or
`borehole. The rubber requires high pressures to set, and the
`inflatable packers that have been used will not hold the large
`differential pressures of those using rubber packers. An alter-
`native is desirable that would not require large amount of
`force to set, but that would handle large differential pres sures.
`Because of the variety of devices disclosed in the current
`application, specific examples of prior art devices are more
`fully discussed before the inventive alternative is disclosed.
`
`SUMMARY OF THE INVENTION
`
`Numerous devices that utilize magnetorheological fluids
`are disclosed for use in oil and gas drilling and/or production.
`With their ability to act as solid-state valves, MR fluids can
`serve in areas such as l) fluid valving systems for locking and
`safety devices, 2) hydraulic logic systems, 3) position control
`and shock absorption, and 4) acting as a valve for other fluids.
`In locking and safety devices, it is disclosed to use MR
`fluids as a hydraulic fluid that controls a piston designed to
`initiate an event. The presence of a magnetic field can prevent
`the piston from moving, acting as a safety lock for critical
`events. Examples are given for tubing conveyed perforation
`(TCP) guns, but are practical for many other locking appli-
`cations.
`
`In hydraulic logic systems, it is disclosed to utilize MR
`fluid valves that have a logic value of “0” or “1 ” depending on
`whether or not a magnetic field is present. Systems can be
`designed to control downhole equipment by logical responses
`to sensor input. Valves can be tied together to create more
`complex logic
`It is further disclosed to control the position of one device
`relative to another device by MR systems. Movement of the
`devices relative to each other is tied to the movement of a
`
`piston through MR fluid; by blocking the flow of the MR
`fluid, the relative positions ofthe pieces are fixed. A magnetic
`field that is below that necessary to block flow can provide a
`time-delay or dampening effect.
`In packers, it is disclosed to utilize an MR fluid in a packer,
`or other device to block the flow of other fluids. By solidifying
`the MR fluid, the seal can provide a strong barrier to the
`passage of other fluids, while its ability to have a fluid phase
`allows the MR fluid to conform to the walls of damaged
`wellbores. Little force is require to set the packer, yet it can
`hold large differential pressures.
`
`MEGCO EX. 1014
`
`MEGCO Ex. 1014
`
`

`

`US 7,428,922 B2
`
`3
`Devices utilizing MR fluids will have one or more of the
`following advantages: they are generally simple designs, fit
`well into existing systems, have fewer moving parts, and can
`be designed to fail (if electrical connections are lost) in either
`a valve open or valve closed position. The MR fluid itself is
`relatively inexpensive, easily handled, non-toxic, and its vis-
`cosity can be varied by simply changing the magnetic field to
`which it is subjected. Magnetorheological fluid devices can
`offer simple, elegant solutions to a number of problems, as
`will be further discussed.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The novel features believed characteristic of the invention
`
`are set forth in the appended claims. The invention itself,
`however, as well as a preferred mode of use, further objects
`and advantages thereof, will best be understood by reference
`to the following detailed description of an illustrative
`embodiment when read in conjunction with the accompany-
`ing drawings, wherein:
`FIG. 1 shows an exemplary graph of the flow rate of a
`magnetorheological fluid versus the field strength of mag-
`netic field applied to the fluid.
`FIGS. 2A7E show various methods of constructing a mag-
`netorheological valve assembly from magnets and/or electro-
`magnets.
`FIGS. 3A and 3B show less desirable methods of interrupt-
`ing the magnetic flow.
`FIG. 4 shows a conventional pressure-operated firing head
`for a perforation gun.
`FIG. 5 shows an exemplary firing head designed with an
`MR fluid control
`
`FIGS. 6A and B show an alternate embodiment of firing
`head designed with an MR fluid control before and during
`firing
`FIGS. 7A7C show another example of a firing pin with a
`lock and/or time delay feature provided by MR fluid.
`FIGS. 8A7C show a prior art circulating valve.
`FIG. 9A shows a three-way valve such as can be used in a
`circulating valve, while FIGS. 9B7C demonstrates the valves
`in the tubing that can be controlled by the three-way valve.
`FIGS. 10A7C show a prior art travel joint in a drill string,
`in both a locked and an unlocked position.
`FIG. 11 shows a partial cutaway of a travel joint designed
`to utilize MR fluid for position control.
`FIG. 12 shows a schematic ofa number of downhole pieces
`of equipment, each tied to high-pressure and low-pressure
`control lines and controlled through the use of magnetorheo-
`logical valves.
`FIG. 13 shows a magnetorheological valve that would
`reflect the logical function ofan exclusive “OR” applied to the
`two inputs.
`FIGS. 14A£ show a packer, utilizing MR fluid, which can
`be set with little effort, but which can withstand a large
`pressure differential across the packer.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`
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`Embodiment ofthe disclosed system will now be discussed
`in further detail.
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`Overview of Valves Using Magnetorheological Fluid
`It is well known that ifone side ofan O-shapedpiece ofiron
`is wrapped with coils of an insulated conductor, an electro-
`magnet can be formed. When a direct current is run through
`the coils, the iron underneath the coils is temporarily magne-
`tized, with the polarity depending on the direction of current.
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`The O-shaped piece of iron acts in a manner analogous to an
`electrical circuit to conduct the magnetic field, or flux, around
`the magnetic circuit created, so that the entire piece of iron
`becomes an electromagnet. If, however, a section of the mag-
`netic circuit is removed, the magnetic field cannot flow, just as
`in an electrical circuit. FIG. 2A shows a circuit similar to that
`
`described above, except that a passageway 212 containing
`magnetorheological
`fluid replaces one
`section of the
`O-shaped iron 200. When the direct current is passed (shown
`by darkened coils) through the coils 210, the iron in the MR
`fluid completes the magnetic circuit. The MR fluid that is part
`ofthe circuit thickens or solidifies (shown by the lines offorce
`through the fluid), depending on the strength of the magnetic
`field, while portions that are not subjected to the magnetic
`field remain liquid. In this embodiment, current is required to
`keep the valve closed, while a lack of current, shown in FIG.
`2B, maintains the valve in an open position, with the MR fluid
`liquid (no lines of force).
`It is also possible to design a valve in which a lack of
`current closes a valve, while a current opens the valve. FIG.
`2C shows an embodiment utilizing a combination of a per-
`manent magnet and an electromagnet. Rather than using an
`O-shapedpiece ofiron, as in the previous example, an annular
`magnet 205 is used, with coils 210 wrapped around one
`section of the magnet 205. Because of the constant magnetic
`field created by the permanent magnet (note the lines of
`force), MR fluid in the passageway 212 will remain solidified
`until the flow of magnetic force is disrupted. In FIG. 2D, a
`current is supplied to the electromagnet, giving it a polarity
`which is opposite the polarity of the permanent magnet (note
`the opposing lines of force). The field strength of the electro-
`magnet can be adjusted so that the field of the electromagnet
`cancels the field of the permanent magnet and the magnetic
`flux no longer flows. This allows the MR fluid to liquefy,
`opening the valve. FIG. 2E shows an alternate version of the
`valve of FIG. 2D. In this embodiment, it is more efficient to
`cancel the magnetic field only in the working gap (the con-
`tainer 212 of MR fluid) by redirecting the flux from the
`permanent magnet to a secondary, higher reluctance gap 220.
`If the coil 210 is off, most of the flux from the permanent
`magnet 205 flows through the primary gap 212 and solidifies
`the MR fluid, effectively closing the valve. If the coil 210 is
`activated, the electromagnet’s flux cancels the flux from the
`permanent magnet at the primary gap 212, but doubles the
`flux at the secondary gap 220. This effectively redirects the
`flux to the secondary gap and opens the MR valve.
`FIG. 3A shows an alternate means of negating the effect of
`the magnet 205 on the MR fluid in container 212. In this
`embodiment, the magnetic field is shunted through a piece of
`steel 310 that provides a short circuit, allowing the flux to flow
`without going through the section containing the MR fluid.
`FIG. 3B shows a method of interrupting the flow of flux by
`simply removing a piece 312 ofthe magnetic circuit, creating
`an open circuit. Both of these two embodiments require the
`movement of part of the circuit, to either add or remove a
`conductive piece. This could be done by applying fluid pres-
`sure, hydraulic pressure or mechanical force, but as the aim is
`to simplify the valve, these are much less preferred.
`Building further on the use of MR fluids, the inventors of
`this application have identified a number of specific areas in
`downhole drilling and production in which magnetorheologi-
`cal fluid valves can be useful. These areas generally fall into
`four categories: fluid valves for locking and safety devices,
`hydraulic control circuits, position control, and blocking the
`flow of other fluids and will be discussed in these four general
`groups. Some applications do not fall easily into these group-
`ings, but will be discussed where most appropriate.
`
`MEGCO EX. 1014
`
`MEGCO Ex. 1014
`
`

`

`US 7,428,922 B2
`
`5
`Fluid Valves for Locking and Safety Devices
`Locking and safety devices are devices that have a one-
`time operation, such that the system cannot be reestablished
`to its original condition. When dealing with the heavy equip-
`ment and high pressures inherent in oilfield work, safety
`becomes a very important issue, and fail-safe mechanisms are
`mandatory. Locking mechanisms are used to ensure that a
`desired action, such as detonation of a perforation gun, does
`not take place prematurely. Using solid-state magnetorheo-
`logical valves as described above, safety devices can be
`locked in an immovable state until a magnetic field is
`removed using an electromagnet.
`In a first application, we will look at a control system for a
`firing head in a tubing-conveyed perforation (TCP) gun that is
`operated using MR fluids. First, let us look closer at the
`problems in this area. Conventionally, a perforating gun is
`actuated through a firing head that is responsive either to
`mechanical forces, such as the impact provided by dropping
`a detonating bar through the tubing, or to fluid pressure, e. g.,
`through hydraulic lines. Additionally, some hybrid systems
`exist. Such firing heads, where the piston is moved in
`response to hydraulic pressure, are believed to enhance the
`safety of the detonating system in that they are unlikely to
`detonate without a specific source of substantial fluid pres-
`sure, which would not be expected outside the wellbore.
`To provide added safety, especially for a mechanically
`actuated firing head, detonation interruption devices are also
`used. These devices are typically attached between the firing
`head assembly and the perforating gun, and typically contain
`a eutectic alloy that melts at temperatures expected within a
`wellbore, but not at the surface, for example 1350 F. In its
`solid form, the eutectic material prevents the detonation sig-
`nal from reaching the perforating gun, preventing accidental
`detonation at the surface. When the device is downhole, the
`increased heat will melt the material and allow detonation.
`
`However, “normal” drilling conditions vary widely. Detona-
`tion interruption devices are very difficult to store in Saudi
`Arabia, for example, as surface temperatures can reach the
`material’s melting point. In areas like Alaska, the opposite
`problem occurs, as downhole temperatures may only reach
`70° F., preventing detonation when desired. These operations
`would typically rely on a pressure-operated firing head.
`One example of a conventional pressure-operated firing
`head is seen in FIG. 4. A perforation gun is fired when the
`firing piston 410, powered by pressure applied through pres-
`sure port 418, contacts initiator 412. The pressure system is
`typically hydraulic, which means that as the well depth
`increases, the inherent hydraulic pressure in the pressure line
`becomes significant. In order to prevent accidental firings,
`shear pins 414, held by shear sleeve 416, hold firing piston
`410 in place. To fire the gun, the pressure through pressure
`ports 418 is increased until shear pins 414 shear off, allowing
`firing piston 410 to move and strike initiator 412. As well
`depths increase, the number of shear pins necessary to hold
`the piston in place increases, with a concomitant rise in the
`pressure necessary to shear the pins. This increase can create
`additional problems depending on formation pressure and
`other completion equipment. The actuating pressures can
`become so high that either other equipment in the well cannot
`withstand it, or additional pressure would result in the well
`being completed in an over-balanced state as opposed to an
`under-balanced state. Thus, either safety factors are reduced
`or another means of firing must be found.
`FIG. 5 shows a firing head designed with an MR fluid
`control. In this design, pressure port 518 is initially blocked
`by fluid piston 520, so that no pressure can be applied to firing
`piston 510. As the firing gun is lowered into the borehole,
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`pressure would build up at pressure ports 518, tending to
`move fluid piston 520 upward and opening the pressure ports
`518 to the firing piston 510. However, the movement of fluid
`piston 520 is prevented by the presence of MR fluid 524, held
`in place by solid MR fluid 526 between portions of magnetic
`assembly 522. Note that the magnetic assembly will be
`designed with a permanent magnet, so that the un-powered
`state ofthe valve is closed. The firing piston is not pressurized
`in this embodiment until the pressure ports are opened, so a
`single shear pin 514 is enough to hold firing piston 510 in
`place. To fire the gun, an electromagnet is actuated to coun-
`teract the magnetic field ofmagnetic assembly 522. Solid MR
`fluid 526 is liquefied, allowing MR fluid 524 to move into the
`fluid reservoir 528. This, in turn allows fluid piston 520 to
`move, opening pres sure port 518, the pres sure then breaks the
`shear pin and allows firing piston 510 to strike initiator 512.
`Using an MR fluid controlled safety lock on the TCP gun
`gives a much safer application. The safety is provided by a
`permanent magnet that can prevent movement, and only the
`intentional act of canceling the magnetic field will allow the
`gun to fire.
`An alternate embodiment of the firing head is seen in FIG.
`6A. In this embodiment, firing piston 610 is held away from
`initiator 612, not by shear pins, but by a collet restraint 616.
`When installed, the collet restraint 616 is held in an open
`position by a portion of the fluid piston 620. In this open
`position, the outside diameter of collet restraint 616 is larger
`than the diameter of the firing piston 610 and cannot traverse
`the cylindrical surface 614 that contains the firing piston 610.
`Pressure communication ports 618 are in fluid communica-
`tion with the surface 630 ofthe fluid piston 620, but are unable
`to move fluid piston 620, because of the solid MR fluid
`formed between sections of magnetic assembly 622. FIG. 6B
`shows this same embodiment after the magnetic flux between
`magnetic assemblies 622 have been cancelled, allowing solid
`MR fluid 626 to liquefy. This, in turn, allows the fluid piston
`620 to be pushed away from the collet restraint 616, so that the
`collet restraint 616 can collapse inward, allowing the firing
`piston 610 to strike initiator 612.
`In either of the MR embodiments above, it would be pos-
`sible to add a time-delay feature to the firing of the guns by a
`simple means. Rather than entirely canceling the magnetic
`field in magnetic assembly 622, the field can be partially
`cancelled, so that the MR fluid in the gap is in a semi-solid
`state with a given flow rate. The chosen flow rate would
`determine the time necessary for the pressure ports 618 to
`open and fire the guns. Many other embodiments can also be
`designed to enable time delay.
`FIGS. 7A7C provide another example of a firing pin with a
`lock and/or time delay feature provided by MR fluid. In the
`prior art, delayed firing could be achieved by a pyrotechnic
`delay element, which is expensive, or a fluid delay, which
`requires a complex spring mechanism and expensive orifices
`that are susceptible to clogging and failing. MR fluid control
`offers an inexpensive, simple alternative. In this example, a
`cylindrical piston 712 moves through a cylinder 714 contain-
`ing MR fluid 716. Fluid that is displaced by the piston travels
`up a tube 718 that goes through the center of the piston, to be
`collected in the region behind the piston. A magnetic assem-
`bly 722 can produce a magnetic field through the tube 718, to
`either slow or stop the progress ofthe piston through the fluid.
`When the magnetic field is strong enough to solidify the MR
`fluid, it acts as a lock; when the magnetic field is lower, a
`semi-solid plug of MR fluid 724 will a delay the movement of
`the piston in a predictable manner. This can be used, for
`instance, to provide a fuse in which the firing does not occur
`immediately after the event is triggered, but is delayed for a
`
`MEGCO EX. 1014
`
`MEGCO Ex. 1014
`
`

`

`US 7,428,922 B2
`
`7
`given period oftime. The sequence ofdrawings, FIGS. 7A7C,
`shows the piston as is descends. The time necessary for piston
`712 to descend until firing pin 730 contacts explosive initiator
`732 can be varied by varying the strength ofthe magnetic field
`produced by assembly 722.
`The use of MR fluid in implementing a TCP gun is only one
`example in which a safety lock or time-delay feature can be
`implemented using an MR valve. A valve using MR fluid can
`be used in any tool that relied on a failure mechanism to allow
`movement, such as vent devices that rely on shear pins, set-
`ting packers that rely on brass lugs, valves that rely on rupture
`discs, secondary release mechanisms that rely on shear pins
`or the shear ofthreads, live well intervention tools that rely on
`collapsing springs or shear pins, sub-surface safety valves,
`bridge plugs, etc. Many others will occur to one of ordinary
`skill in the art.
`
`Position Control
`Position control is defined in this context as a device that
`
`can repeatably have multiple positions that include restoring
`the device to its original position. To