Method and apparatus for selective injection or flow control with through-tubing operation capacity

Information

  • Patent Grant
  • 6631767
  • Patent Number
    6,631,767
  • Date Filed
    Tuesday, November 16, 1999
    25 years ago
  • Date Issued
    Tuesday, October 14, 2003
    21 years ago
Abstract
A downhole flow control device is provided for remotely controlling fluid flow of production or injection fluids, and may offer the capacity to pass wireline tools therethrough. In a broad aspect, the device may include: a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; and a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port. The device may also include: a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions; means for selectively controlling movement of the first sleeve member to regulate fluid flow through the at least one flow port; and a cone member for directing fluid flow into the annular space.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to subsurface well equipment and, more particularly, to a method and apparatus for remotely controlling injection or production fluids in well completions which may include gravel pack.




2. Description of the Related Art




As is well known to those of skill in the art, certain hydrocarbon producing formations include sand. Unless filtered out, such sand can become entrained or commingled with the hydrocarbons that are produced to the earth's surface. This is sometimes referred to as “producing sand”, and can be undesirable for a number of reasons, including added production costs, and erosion of well tools within the completion, which could lead to the mechanical malfunctioning of such tools. Various approaches to combating this problem have been developed. For example, the industry has developed sand screens which are connected to the production tubing adjacent the producing formation to prevent sand from entering the production tubing. In those cases where sand screens alone will not sufficiently filter out the sand, the industry has learned that a very effective way of filtering sand from entry into the production tubing is to fill, or pack, the well annulus with gravel, hence the term “gravel pack” completions.




A drawback to gravel pack completions arises when it is desired to connect a remotely-controllable flow control device to the production tubing to regulate the flow of production fluids from the gravel-packed well annulus into the production tubing, or to regulate the flow of injection fluids from the production tubing into the gravel-packed well annulus. If the flow control device is of the type that includes a flow port in the sidewall of the body establishing fluid communication between the well annulus and the interior of the tool (such as the flow control device disclosed in U. S. Pat. No. 5,823,623), then the presence of gravel pack in the annulus adjacent the flow port may present an obstacle to the proper functioning of the flow control device, to the extent that the gravel pack may prohibit laminar flow through the flow port. As such, it is an object of the present invention to provide a flow control device that will enable the remote control of flow of production fluids and/or injection fluids in well completions where the annulus is packed with gravel. It is also an object of the present invention to provide such a tool that will enable the passage of wireline tools through the tool so that wireline intervention techniques may be performed at locations in the well below the flow control device.




SUMMARY OF THE INVENTION




The present invention has been contemplated to meet the above described needs. In a broad aspect, the invention may be a downhole flow control device comprising: a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; and a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port. Another feature of this aspect of the present invention is that the device may further include a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore. Another feature of this aspect of the present invention is that the device may further include means for moving the closure member between its open and closed positions. Another feature of this aspect of the present invention is that the device may further include means for selectively controlling movement of the first sleeve member to regulate fluid flow through the at least one flow port. Another feature of this aspect of the present invention is that the device may further include means for directing fluid flow into the annular space.




In another aspect, the present invention may be a downhole flow control device comprising: a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; and a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions. Another feature of this aspect of the present invention is that the second bore has a diameter greater than a diameter of the first bore. Another feature of this aspect of the present invention is that the first sleeve member further includes at least one flow slot. Another feature of this aspect of the present invention is that the closure member is a flapper hingedly connected to the extension member. Another feature of this aspect of the present invention is that the second sleeve member includes an inner surface having a locking profile for mating with a shifting tool. Another feature of this aspect of the present invention is that the second sleeve member includes at least one rib releasably engageable with at least one annular recess within the first bore of the extension member. Another feature of this aspect of the present invention is that the second sleeve member includes a plurality of collet sections having a plurality of ribs disposed thereon for releasable engagement with at least one annular recess within the first bore of the extension member. Another feature of this aspect of the present invention is that the second sleeve member includes at least one first equalizing port for cooperating with at least one second equalizing port in the extension member to equalize pressure on opposed sides of the closure member prior to shifting the closure member to its open position. Another feature of this aspect of the present invention is that the device may further include seal means for preventing fluid communication between the at least one first and second equalizing ports when the second sleeve member is in a non-equalizing position. Another feature of this aspect of the present invention is that the device may further include a cone member connected to a distal end of the extension member. Another feature of this aspect of the present invention is that the cone member includes a first half-cone member and a second half-cone member, each-being hingedly connected to the distal end of the extension member and biased towards each other in a normally-closed position. Another feature of this aspect of the present invention is that an angle formed between a first outer surface of the first half-cone member and a second outer surface of a second half-cone member is approximately forty-four degrees when the cone member is in its normally-closed position. Another feature of this aspect of the present invention is that the second sleeve member is remotely shiftable to a lower position in which the first and second half-cone members are shifted to open positions in which a first inner surface of the first half-cone member is disposed about the second sleeve member, and a second inner surface of the second half-cone member is disposed about the second sleeve member. Another feature of this aspect of the present invention is that the device may further include a piston connected to the first sleeve member and movably disposed within the body member in response to application of pressure. Another feature of this aspect of the present invention is that the device may further include a first hydraulic conduit connected between a source of pressurized fluid and the body member, and being in fluid communication with a first side of the piston. Another feature of this aspect of the present invention is that the device may further include a spring disposed within the body member and biasing the first sleeve member and the second valve seat toward the first valve seat. Another feature of this aspect of the present invention is that the device may further include a contained source of pressurized gas in fluid communication with a second side of the piston. Another feature of this aspect of the present invention is that the pressurized gas is contained within a gas conduit connected to the body member. Another feature of this aspect of the present invention is that the device may further include a second hydraulic conduit connected between the source of pressurized fluid and the body member, and being in fluid communication with a second side of the piston. Another feature of this aspect of the present invention is that the device may further include a port in the body member establishing fluid communication between a well annulus and a second side of the piston. Another feature of this aspect of the present invention is that the device may further include a position holder cooperably engageable with a retaining member, one of the position holder and the retaining member being connected to the first sleeve member, and the other of the position holder and the retaining member being connected to the body member. Another feature of this aspect of the present invention is that the position holder includes a recessed profile in which a portion of the retaining member is engaged and movably disposed to hold the sleeve member in a plurality of discrete positions. Another feature of this aspect of the present invention is that the recessed profile includes a plurality of axial slots of varying lengths disposed circumferentially about the position holder and in substantially parallel relationship, and corresponding to a plurality of discrete positions for the first sleeve member, each axial slot having a recessed portion and an elevated portion, and each axial slot being connected to its immediately neighboring axial slots by ramped slots leading between corresponding recessed and elevated portions of each neighboring axial slot. Another feature of this aspect of the present invention is that the recessed profile is disposed in an indexing cylinder rotatably disposed about the first sleeve member. Another feature of this aspect of the present invention is that the indexing cylinder and the sleeve member are adapted to restrict longitudinal movement therebetween. Another feature of this aspect of the present invention is that the retaining member includes an elongate body having a cam finger at a distal end thereof engaged with and movably disposed within a recessed profiled in the position holder, and a proximal end of the elongate body being hingedly attached to one of the sleeve member and body member. Another feature of this aspect of the present invention is that the device may further include means for biasing the retaining member into engagement with the position holder.




In another aspect, the invention may be a downhole flow control device comprising: a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions; and a cone member connected to a distal end of the extension member. Another feature of this aspect of the present invention is that the cone member includes a first half-cone member and a second half-cone member, each being hingedly connected to the distal end of the extension member and biased towards each other in a normally-closed position. Another feature of this aspect of the present invention is that an angle formed between a first outer surface of the first half-cone member and a second outer surface of a second half-cone member is approximately forty-four degrees when the cone member is in its normally-closed position. Another feature of this aspect of the present invention is that the first sleeve member further includes at least one flow slot. Another feature of this aspect of the present invention is that the closure member is a flapper hingedly connected to the extension member. Another feature of this aspect of the present invention is that the device may further include a piston connected to the first sleeve member and movably disposed within the body member in response to application of pressure. Another feature of this aspect of the present invention is that the device may further include means for moving the piston. Another feature of this aspect of the present invention is that the device may further include means for holding the first sleeve member in a plurality of discrete positions.




In another aspect, the present invention may be a downhole flow control device comprising: a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat; to regulate fluid flow through the at least one flow port; a piston connected to the first sleeve member and movably disposed within the body member; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; and a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions. Another feature of this aspect of the present invention is that the device may further include means for moving the piston within the body member. Another feature of this aspect of the present invention is that the device may further include means for holding the first sleeve member in a plurality of discrete positions. Another feature of this aspect of the present invention is that the first sleeve member further includes at least one flow slot. Another feature of this aspect of the present invention is that the closure member is a flapper hingedly connected to the extension member. Another feature of this aspect of the present invention is that the device may further include a cone member connected to a distal end of the extension member.




In another aspect, the present invention may be a method of producing hydrocarbons from a hydrocarbon formation through a well completion, the well completion including a production tubing disposed within a well casing, a packer connected to the tubing and disposed above the formation, gravel disposed in an annulus between the production tubing and the well casing, a sand screen connected to the tubing and disposed adjacent the formation, and a flow control device connected to the tubing between the sand screen and the packer, the method comprising the steps of: allowing production fluids to flow from the formation through the gravel pack, through the sand screen, into the production tubing, and into the flow control device; regulating fluid flow through the flow control device; and producing the production fluids through the production tubing to a remote location.




In another aspect, the present invention may be a method of injecting fluids through a well completion into a hydrocarbon formation, the well completion including a production tubing disposed within a well casing, a packer connected to the tubing and disposed above the formation, gravel disposed in an annulus between the production tubing and the well casing, a sand screen connected to the tubing and disposed adjacent the formation, and a flow control device connected to the tubing between the sand screen and the packer, the method comprising the steps of: allowing injection fluids to flow from a remote location into the flow control device; regulating flow of the injection fluids through the flow control device; and injecting the injection fluids into the formation.




In another aspect, the present invention may be a method of producing hydrocarbons from a hydrocarbon formation through a well completion, the well completion including a production tubing disposed within a well casing, a packer connected to the tubing and disposed above the formation, gravel disposed in an annulus between the production tubing and the well casing, and a flow control device having a body member and a first sleeve member, the body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore, and the first sleeve member being remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port, the method comprising the steps of: allowing production fluids to flow from the formation through the gravel pack, into the production tubing, and into the annular space; shifting the first sleeve member to separate the first and second valve seats to permit fluid communication between the first bore and the annular space; producing the production fluids through the production tubing to a remote location. Another feature of this aspect of the present invention is that the method may further include the step of shifting the first sleeve member to regulate fluid flow through the at least one flow port.




In another aspect, the present invention may be a well completion including: a well casing in fluid communication with a first hydrocarbon formation; a production tubing disposed within the well casing; gravel packed in an annulus between the well casing and the production tubing; a first packer connected to the tubing and disposed above the first hydrocarbon formation; a first sand screen adjacent the first hydrocarbon formation, connected to the tubing, and establishing fluid communication between the first hydrocarbon formation and the production tubing; a first flow control device connected to the tubing and disposed between the first packer and the first hydrocarbon formation, the first flow control device having a body member and a first sleeve member, the body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore, and the first sleeve member being remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port. Another feature of this aspect of the present invention is that the first end of the body member is positioned above the second end of the body member. Another feature of this aspect of the present invention is that the second end of the body member is positioned above the first end of the body member. Another feature of this aspect of the present invention is that the well completion may further include a first hydraulic conduit connected between a source of pressurized fluid and the first flow control device. Another feature of this aspect of the present invention is that the completion may further include: a second packer connected to the tubing and disposed below the first hydrocarbon formation and above a second hydrocarbon formation; a second sand screen adjacent the second hydrocarbon formation, connected to the tubing, and establishing fluid communication between the second hydrocarbon formation and the production tubing; and a second flow control device connected to the tubing and disposed between the second packer and the first hydrocarbon formation, the second flow control device having a body member and a first sleeve member, the body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore, and the first sleeve member being remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port. Another feature of this aspect of the present invention is that the completion may further include a second hydraulic conduit connected between the source of pressurized fluid and the second flow control device.











BRIEF DESCRIPTION OF THE DRAWINGS





FIGS. 1A-1J

taken together form a longitudinal sectional view of a specific embodiment of the flow control device of the present invention.





FIG. 2

is a cross-sectional view taken along line


2





2


of FIG.


1


B.





FIG. 3

is a cross-sectional view taken along line


3





3


of FIG.


1


E.





FIG. 4

is a cross-sectional view taken along line


4





4


of FIG.


1


E.





FIG. 5

is a cross-sectional view taken along line


5





5


of FIG.


1


E.





FIG. 6

illustrates a planar projection of an outer cylindrical surface of a position holder shown in

FIGS. 1C and 1D

.





FIG. 7

is a partial elevation view taken along line


7





7


of FIG.


11


.





FIG. 8

is a longitudinal sectional view, similar to

FIGS. 1A and 1B

, showing an upper portion of another specific embodiment of the flow control device of the present invention.





FIG. 9

is a longitudinal sectional view, similar to

FIG. 8

, showing an upper portion of another specific embodiment of the flow control device of the present invention.





FIG. 10

is a schematic representation of a specific embodiment of a well completion in which the flow control device of the present invention may be used.




While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.











DETAILED DESCRIPTION OF THE INVENTION




For the purposes of this description, the terms “upper” and “lower,” “up hole” and “downhole” and “upwardly” and “downwardly” are relative terms to indicate position and direction of movement in easily recognized terms. Usually, these terms are relative to a line drawn from an upmost position at the earth's surface to a point at the center of the earth, and would be appropriate for use in relatively straight, vertical wellbores. However, when the wellbore is highly deviated, such as from about 60 degrees from vertical, or horizontal, these terms do not make sense and therefore should not be taken as limitations. These terms are only used for ease of understanding as an indication of what the position or movement would be if taken within a vertical wellbore.




Referring to the drawings in detail, wherein like numerals denote identical elements throughout the several views, a specific embodiment of the downhole flow control device of the present invention is referred to generally by the numeral


10


. Referring initially to

FIG. 1A

, the device


10


may include a generally cylindrical body member


12


having a first bore


14


extending from a first end


16


of the body member


12


and through a generally cylindrical extension member


17


(

FIGS. 1E-1I

) disposed within the body member


12


, and a second bore


18


extending from a second end


20


of the body member


12


and into an annular space


21


disposed about the extension member


17


. In a specific embodiment, the diameter of the second bore


18


is greater than the diameter of the first bore


14


. As shown in

FIG. 1E

, the body member


12


may also include a first valve seat


22


disposed within the first bore


14


, and the extension member


17


may include at least one flow port


24


establishing fluid communication between the annular space


21


and the first bore


14


.




With reference to

FIGS. 1B-1F

, the device


10


may further include a first generally cylindrical sleeve member


26


movably disposed and remotely shiftable within the first bore


14


. The manner in which the first sleeve member


26


is shifted within the first bore


14


will be described below. Referring to

FIG. 1E

, the first sleeve member


26


may include a second valve seat


28


adapted for cooperable sealing engagement with the first valve seat


22


to regulate fluid flow through the at least one flow port


24


. The first sleeve member


26


may also include at least one flow slot


30


.




As shown in

FIG. 1H

, the device


10


may further include a closure member


32


disposed for movement between an open and a closed position to control fluid flow through the first bore


14


. The closure member


32


is shown in its closed position. In a specific embodiment, the closure member


32


may be a flapper having an arm


34


hingedly connected to the extension member


17


. The flapper


32


may be biased into its closed position by a hinge spring


36


. Other types of closure members


32


are within the scope of the present invention, including, for example, a ball valve.




As shown in

FIGS. 1F-1H

, the device


10


may further include a second sleeve member


38


movably disposed and remotely shiftable within the first bore


14


to move the closure member


32


between its open and closed positions. As shown in

FIG. 1E

, the second sleeve member


38


may include an inner surface


40


having a locking profile


42


disposed therein for mating with a shifting tool (not shown). As shown in

FIG. 1G

, the second sleeve member


38


may also include at least one rib


44


that is shown engaged with a first annular recess


46


in the first bore


14


of the extension member


17


. In a specific embodiment, the second sleeve member


38


may include a plurality of ribs


44


disposed on a plurality of collet sections


48


in the second sleeve member


38


that may be disposed between a plurality of slots


50


in the second sleeve member


38


. As will be more fully discussed below, the second sleeve member


38


may be shifted downwardly to engage the ribs


44


with a second annular recess


47


in the first bore


14


of the extension member


17


. The second sleeve member


38


may further include at least one first equalizing port


52


for cooperating with at least one second equalizing port


54


in the extension member


17


to equalize pressure above and below the flapper


32


prior to shifting the second sleeve member


38


downwardly to open the flapper


32


. The first equalizing port


52


establishes fluid communication between the inner surface


40


of the second sleeve member


38


and the first bore


14


of the extension member


17


. The second equalizing port


54


establishes fluid communication between the first bore


14


of the extension member


17


and the annular space


21


. A first annular seal


56


and a second annular seal


58


may be disposed within the first bore


14


of the extension member


17


and in sealing relationship about the second sleeve member


38


. The second equalizing port


54


is disposed between the first and second annular seals


56


and


58


. When the ribs


44


on the second sleeve member


38


are engaged with the first annular recess


46


in the extension member


17


, the first annular seal


56


is disposed between the first and second equalizing ports


52


and


54


, and a distal end


39


of the second sleeve member


38


is spaced from the closure member


32


.




When it is desired to open the flapper


32


, to enable passage of wireline tools (not shown) to positions below the device


10


, a wireline shifting tool (not shown) may be engaged with the locking profile


42


(

FIG. 1G

) and used to shift the second sleeve member


38


downwardly until the distal end


39


(

FIG. 1H

) of the second sleeve member


38


comes into contact with the flapper


32


. This will align the first and second equalizing ports


52


and


54


, and thereby establish fluid communication between the annular space


21


and the inner surface


40


of the second sleeve member


38


. In this manner, pressure may be equalized above and below the flapper


32


prior to opening of the flapper


32


. The second sleeve member


38


may then continue downwardly to push the flapper


32


open, without having to overcome upward forces imparted to the flapper


32


by pressure below the flapper


32


. It is noted, with reference to

FIG. 1E

, that pressure above and below the flapper


32


may also be equalized prior to opening of the flapper


32


by shifting the first sleeve member


26


to separate the first and second valve seats


22


and


28


to establish fluid communication between the annular space


21


and an inner surface


27


of the first sleeve member


26


.




With reference to

FIGS. 1I and 7

, the device


10


may further include a cone member


60


connected to a distal end


62


of the extension member


17


. In a specific embodiment, the cone member


60


may include a first and a second half-cone member


64


and


66


, each of which may be hingedly attached to the distal end


62


of the extension member


17


, as by a first and a second hinge pin


68


and


70


, respectively, and biased towards each other, as by first and second hinge springs


72


and


74


, respectively. The springs


72


and


74


bias and hold the half-cone members


64


and


66


in mating relationship, or in a normally-closed position, to form a cone, as shown in FIG.


1


I. In this normally-closed position, the cone member


60


directs fluid flowing from the second end


20


of the body member


12


into the annular space


21


, and functions to minimize turbulence as fluid flows into the annular space


21


. In this regard, in a preferred embodiment, an angle a formed between a first outer surface


65


of the first half-cone member


64


and a second outer surface


67


of the second half-cone member


66


may be approximately forty-four (44) degrees when the half-cone members


64


and


66


are biased towards each other to form a cone, as shown in FIG.


1


I. When it is desired to pass a wireline tool through the device


10


from the first end


16


of the body member


12


to the second end


20


of the body member, then the second sleeve member


38


(

FIGS. 1F-1H

) may be shifted downwardly (by locating a wireline shifting tool (not shown) in the locking profile


42


, as discussed above) from its position shown in

FIGS. 1F-1H

to a lower position (not shown) in which the first and second half-cone members


64


and


66


are separated and their respective inner surfaces


69


and


70


are disposed about the second sleeve member


38


. With reference to

FIG. 1G

, the ribs


44


on the second sleeve member


38


may be disposed within the second annular recess


47


in the extension member


17


when the second sleeve member


38


is in its lower position (not shown).




The manner in which the first sleeve member


26


is remotely shifted will now be described. Referring to

FIGS. 1B-1D

, in a specific embodiment, a piston


76


may be connected to, or a part of, the first sleeve member


26


, and may be sealably, slidably disposed within the first bore


14


of the body member


12


. In a specific embodiment, the piston


76


may be an annular piston or at least one rod piston. A first hydraulic conduit


78


is connected between a source of hydraulic fluid (not shown), such as at the earth's surface (not shown), and the body member


12


, as at fitting


81


, and is in fluid communication with a first side


80


of the piston


76


, such as through a first passageway


79


in the body member


12


. The first sleeve member


26


may be remotely shifted downwardly, or away from the first end


16


of the body member


12


, by application of pressurized fluid to the first side


80


of the piston


76


. A number of mechanisms for biasing the first sleeve member


26


upwardly, or towards the first end


16


of the body member


12


, may be provided within the scope of the present invention, including but not limited to another hydraulic conduit, pressurized gas, spring force, and annulus pressure, and/or any combination thereof.




In a specific embodiment, as shown in

FIG. 1A

, the biasing mechanism may include a source of pressurized gas, such as pressurized nitrogen, which may be contained within a sealed chamber, such as a gas conduit


82


. An upper portion


84


of the gas conduit


82


may be coiled within a housing


85


formed within the body member


12


, and a lower portion


86


of the gas conduit


82


(

FIG. 1B

) may extend outside the body member


12


and terminate at a fitting


88


connected to the body member


12


. The gas conduit


82


is in fluid communication with a second side


90


of the piston


76


, such as through a second passageway


92


in the body member


12


. Appropriate seals are provided to contain the pressurized gas. As shown in

FIG. 3

, the body member


12


may include a charging port


94


, which may include a dill core valve, through which pressurized gas may be introduced into the device


10


.




Another biasing mechanism is shown in

FIG. 8

, which is a view similar to

FIGS. 1A and 1B

, and illustrates an upper portion of another specific embodiment of the present invention, which is referred to generally by the numeral


10


′. The lower portion of this embodiment is the same as shown in

FIGS. 1C-1I

. In this embodiment, a second hydraulic conduit


96


is connected between a source of hydraulic fluid (not shown), such as at the earth's surface (not shown), and the body member


12


′, and is in fluid communication with the second side


90


′ of the piston


76


′, such as through the second passageway


92


′ in the body member


12


′. As such, in this embodiment, hydraulic fluid is used instead of pressurized gas to bias the first sleeve member


26


′ towards the first end


16


′ of the body member


12


′.




Another biasing mechanism is shown in

FIG. 9

, which is a view similar to

FIG. 8

, and illustrates an upper portion of another specific embodiment of the present invention, which is referred to generally by the numeral


10


″. The lower portion of this embodiment is as shown in

FIGS. 1C-1I

. In this embodiment, a spring


98


is disposed within the first bore


14


″, about the first sleeve member


26


″, and between an annular shoulder


100


on the body member


12


″ and the second side


90


″ of the piston


76


″. As such, in this embodiment, force of the spring


98


is used instead of pressurized gas or hydraulic fluid to bias the first sleeve member


26


″ toward the first end


16


″ of the body member


12


″. Alternatively, as shown in

FIG. 9

, the device


10


″ may also include a port


102


in the body member


12


″ connected to a conduit


104


through which hydraulic fluid or pressurized gas may also be applied to the second side


90


″ of the piston


76


″ to assist the spring


98


in biasing the first sleeve member


26


″ toward the first end


16


″ of the body member


12


″. In this regard, if hydraulic fluid is desired, the conduit


104


may be a hydraulic conduit, such as the second hydraulic conduit


96


shown in FIG.


8


. Alternatively, if pressurized gas is desired, the conduit


104


may be a gas conduit, such as the gas conduit


82


shown in

FIGS. 1A-1B

. In another specific embodiment, instead of using hydraulic fluid or pressurized gas, the port


102


may be in communication with annulus pressure, which may be used to bias the first sleeve member


26


″ toward the first end


16


″ of the body member


12


″, either by itself, or in combination with the spring


98


.




Referring now to

FIGS. 1C-1D

and


6


, the device


10


of the present invention may also include a position holder to enable an operator at the earth's surface (not shown) to remotely locate and maintain the first sleeve member


26


in a plurality of discrete positions, thereby providing the operator with the ability to remotely regulate fluid flow through the at least one flow port


24


in the extension member


17


(FIG.


1


E), and/or through the at least one flow slot


30


in the first sleeve member


26


(FIG.


1


E). The position holder may be provided in a variety of configurations. In a specific embodiment, as shown in

FIGS. 1C-1D

and


6


, the position holder may include an indexing cylinder


106


having a recessed profile


108


(FIG.


6


), and be adapted so that a retaining member


110


(

FIG. 1D

) may be biased into cooperable engagement with the recessed profile


108


, as will be more fully explained below. In a specific embodiment, one of the position holder


106


and the retaining member


110


may be connected to the first sleeve member


26


, and the other of the position holder


106


and the retaining member


110


may be connected to the body member


12


. In a specific embodiment, the recessed profile


108


may be formed in the first sleeve member


26


, or it may be formed in the indexing cylinder


106


disposed about the first sleeve member


26


. In this embodiment, the indexing cylinder


106


and the first sleeve member


26


are fixed to each other so as to prevent longitudinal movement relative to each other. As to relative rotatable movement between the two, however, the indexing cylinder


106


and the first sleeve member


26


may be fixed so as to prevent relative rotatable movement between the two, or the indexing cylinder


106


may be slidably disposed about the first sleeve member


26


so as to permit relative rotatable movement. In the specific embodiment shown in

FIGS. 1C-1D

, in which the recessed profile


108


is formed in the indexing cylinder


106


, the indexing cylinder


106


is disposed for rotatable movement relative to the first sleeve member


26


, as per roller bearings


112


and


114


, and ball bearings


116


and


118


.




In a specific embodiment, with reference to

FIGS. 1C-1D

, the retaining member


110


may include an elongate body


120


having a cam finger


122


at a distal end thereof and a hinge bore


124


at a proximal end thereof. A hinge pin


126


is disposed within the hinge bore


124


and connected to the body member


12


. In this manner, the retaining member


110


may be hingedly connected to the body member


12


. A biasing member


128


, such as a spring, may be provided to bias the retaining member


110


into engagement with the recessed profile


108


. Other embodiments of the retaining member


110


are within the scope of the present invention. For example, the retaining member


110


may be a spring-loaded detent pin (not shown).




The recessed profile


108


will now be described with reference to

FIG. 6

, which illustrates a planar projection of the recessed profile


108


in the indexing cylinder


106


. As shown in

FIG. 6

, the recessed profile


108


preferably includes a plurality of axial slots


130


of varying length disposed circumferentially around the indexing cylinder


106


, in substantially parallel relationship, each of which are adapted to selectively receive the cam finger


122


on the retaining member


110


. While the specific embodiment shown includes twelve axial slots


130


, this number should not be taken as a limitation. Rather, it should be understood that the present invention encompasses a recessed profile


108


having any number of axial slots


130


. Each axial slot


130


includes a lower portion


132


and an upper portion


134


. The upper portion


134


is recessed, or deeper, relative to the lower portion


132


, and an inclined shoulder


136


separates the lower and upper portions


132


and


134


. An upwardly ramped slot


138


leads from the upper portion


134


of each axial slot


130


to the elevated lower portion


132


of an immediately neighboring axial slot


130


, with the inclined shoulder


136


defining the lower wall of each upwardly ramped slot


138


.




In operation, the first sleeve member


26


is normally biased upwardly, so that the cam finger


122


of the retaining member


110


is positioned against the bottom of the lower portion


132


of one of the axial slots


130


. When it is desired to change the position of the first sleeve member


26


, hydraulic pressure should be applied from the first hydraulic conduit


78


(

FIG. 1B

) to the first side


80


of the piston


76


for a period long enough to shift the cam finger


122


into engagement with the recessed upper portion


134


of the axial slot


130


. Hydraulic pressure should then be removed so that the first sleeve member


26


is biased upwardly, thereby causing the cam finger


122


to engage the inclined shoulder


136


and move up the upwardly ramped slot


138


and into the lower portion


132


of the immediately neighboring axial slot


130


having a different length. It is noted that, in the specific embodiment shown, the indexing cylinder


106


will rotate relative to the retaining member


110


, which is hingedly secured to the body member


12


. By applying and removing pressurized fluid from the first side


80


of the piston


76


, the cam finger


122


may be moved into the axial slot


130


having the desired length corresponding to the desired position of the first sleeve member


26


. This enables an operator at the earth's surface to shift the first sleeve member


26


into a plurality of discrete positions and control the distance between the first and second valve seats


22


and


28


(FIG.


1


E), and thereby regulate fluid flow through the at least one flow port


24


and/or the at least one flow slot


30


.




Methods of using the flow control device


10


of the present invention will be now be explained in connection with a specific embodiment of a well completion denoted generally by the numeral


140


, as illustrated in FIG.


10


. Referring now to

FIG. 10

, the well completion


140


may include a production tubing


142


extending from the earth's surface (not shown) and disposed within a well casing


144


, with a first packer


146


connected to the tubing


142


and disposed above a first hydrocarbon formation


148


, and a second packer


150


connected to the tubing


142


and disposed between the first hydrocarbon formation


148


and a second hydrocarbon formation


152


. A well annulus


154


may be packed with gravel


155


. A first sand screen


156


may be connected to the tubing


142


adjacent the first formation


148


, and a second sand screen


158


may be connected to the tubing


142


adjacent the second formation


152


. A first flow control device


10




a


of the present invention may be connected to the tubing


142


and disposed between the first packer


146


and the first formation


148


, and a second flow control device


10




b


of the present invention may be connected to the tubing


142


and disposed between the first formation


148


and the second packer


150


. A first hydraulic conduit


160


may be connected from a source of pressurized fluid (not shown), such as at the earth's surface (not shown), to the first flow control device


10




a


, and a second hydraulic conduit


162


may be connected from a source of pressurized fluid (not shown), such as at the earth's surface (not shown), to the second flow control device


10




b.






In a specific embodiment, the pressure within the first formation


148


may be greater than the pressure within the second formation


152


. In this case, it may be desirable to restrict fluid communication between the first and second formations


148


and


152


, otherwise hydrocarbons from the first formation


148


would flow into the second formation


152


instead of to the earth's surface. To this end, the first sleeve member


26


(

FIGS. 1A-1G

) within the second flow control device


10




b


may be remotely shifted upwardly to bring the first and second valve seats


22


and


28


into sealing contact, thereby preventing fluid communication between the first and second formations


148


and


152


. The first sleeve member


26


in the first flow control device


10




a


may be remotely shifted to regulate fluid flow from the first formation


148


to the earth's surface. The first and second flow control devices


10




a


and


10




b


may be remotely manipulated as required depending upon which formation is to be produced, and/or whether wireline intervention techniques are to be performed.




The flow control device


10


of the present invention may be used to produce hydrocarbons from a formation, such as formation


148


or


152


, to the earth's surface, or to inject chemicals from the earth's surface (not shown) into the well annulus


154


, and/or into a hydrocarbon formation, such as formation


148


or


152


. If the device


10


is to be used for producing fluids, then the device


10


should be positioned with the first end


16


of the device


10


(

FIG. 1A

) above the second end


20


of the device


10


(FIG.


11


). But if the device


10


is to be used to inject chemicals, then the device


10


should be positioned “upside down” so that the second end


20


is above the first end


16


.




It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials or embodiments shown and described, as obvious modifications and equivalents will be apparent to one skilled in the art. For example, while the device


10


has been described as being remotely controlled via at least one hydraulic conduit (e.g., conduit


78


in FIG.


1


A), the device


10


could just as easily be remotely controlled via an electrical conductor and still be within the scope of the present invention. Additionally, while the device


10


of the present invention has been described for use in well completions which include gravel pack in the well annulus, the device


10


may also be used in well completions lacking gravel pack and still be within the scope of the present invention. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.



Claims
  • 1. A downhole flow control device comprising:a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; and a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions, wherein the second sleeve member includes an inner surface having a locking profile for mating with a shifting tool.
  • 2. A downhole flow control device comprising:a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; and a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions, wherein the second sleeve member includes at least one rib releasably engageable with at least one annular recess within the first bore of the extension member.
  • 3. A downhole flow control device comprising:a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; and a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions, wherein the second sleeve member includes a plurality of collet sections having a plurality of ribs disposed thereon for releasable engagement with at least one annular recess within the first bore of the extension member.
  • 4. A downhole flow control device comprising:a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions, wherein the second sleeve member includes at least one first equalizing port for cooperating with at least one second equalizing port in the extension member to equalize pressure on opposed sides of the closure member prior to shifting the closure member to its open position; and seal means for preventing fluid communication between the at least one first and second equalizing ports when the second sleeve member is in a non-equalizing position.
  • 5. A downhole flow control device comprising:a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions; and a cone member connected to a distal end of the extension member.
  • 6. The downhole flow control device of claim 5, wherein the cone member includes a first halftone member and a second half-cone member, each being hingedly connected to the distal end of the extension member and biased towards each other in a normally-closed position.
  • 7. The downhole flow control device of claim 6, wherein an angle formed between a first outer surface of the first half-cone member and a second outer surface of a second half-cone member is approximately forty-four degrees when the cone member is in its normally-closed position.
  • 8. The downhole flow control device of claim 6, wherein the second sleeve member is remotely shiftable to a lower position in which the first and second half-cone members are shifted to open positions in which a first inner surface of the first half-cone member is disposed about the second sleeve member, and a second inner surface of the second half-cone member is disposed about the second sleeve member.
  • 9. A downhole flow control device comprising:a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; and a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions; a piston connected to the first sleeve member and movably disposed within the body member in response to applications of pressure; a first hydraulic conduit connected between a source of pressurized fluid and the body member, and being in fluid communication with a first side of the piston; and a port in the body member establishing fluid communication between a well annulus and a second side of the piston.
  • 10. A downhole flow control device comprising:a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions, wherein the second sleeve member includes at least one first equalizing port for cooperating with at least one second equalizing port in the extension member to equalize pressure on opposed sides of the closure member prior to shifting the closure member to its open position; and a position holder cooperably engageable with a retaining member, one of the position holder and the retaining member being connected to the first sleeve member, and the other of the position holder and the retaining member being connected to the body member.
  • 11. The downhole flow control device of claim 10, wherein the position holder includes a recessed profile in which a portion of the retaining member is engaged and movably disposed to hold the sleeve member in a plurality of discrete positions.
  • 12. The downhole flow control device of claim 11, wherein the recessed profile includes a plurality of axial slots of varying lengths disposed circumferentially about the position holder and in substantially parallel relationship, and corresponding to a plurality of discrete positions for the first sleeve member, each axial slot having a recessed portion and an elevated portion, and each axial slot being connected to its immediately neighboring axial slots by ramped slots leading between corresponding recessed and elevated portions of each neighboring axial slot.
  • 13. The downhole flow control device of claim 11, wherein the recessed profile is disposed in an indexing cylinder rotatably disposed about the first sleeve member.
  • 14. The downhole flow control device of claim 13, wherein the indexing cylinder and the sleeve member are adapted to restrict longitudinal movement therebetween.
  • 15. The downhole flow control device of claim 10, wherein the retaining member includes an elongate body having a cam finger at a distal end thereof engaged with and movably disposed within a recessed profiled in the position holder, and a proximal end of the elongate body being hingedly attached to one of the sleeve member and body member.
  • 16. The downhole flow control device of claim 10, further including means for biasing the retaining member into engagement with the position holder.
  • 17. A downhole flow control device comprising:a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions; and a cone member connected to a distal end of the extension member.
  • 18. The downhole flow control device of claim 17, wherein the cone member includes a first half-cone member and a second half-cone member, each being hingedly connected to the distal end of the extension member and biased towards each other in a normally-closed position.
  • 19. The downhole flow control device of claim 18, wherein an angle formed between a first outer surface of the first half-cone member and a second outer surface of a second half-cone member is approximately forty-four degrees when the cone member is in its normally-closed position.
  • 20. The downhole flow control device of claim 17, wherein the first sleeve member further includes at least one flow slot.
  • 21. The downhole flow control device of claim 17, wherein the closure member is a flapper hingedly connected to the extension member.
  • 22. The downhole flow control device of claim 17, further including a piston connected to the first sleeve member and movably disposed within the body member in response to application of pressure.
  • 23. The downhole flow control device of claim 22, further including means for moving the piston.
  • 24. The downhole flow control device of claim 17, further including means for holding the first sleeve member in a plurality of discrete positions.
  • 25. A downhole flow control device comprising:a body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore; a first sleeve member remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat; to regulate fluid flow through the at least one flow port; a piston movably disposed within the body member; a closure member disposed for movement between an open and a closed position to control fluid flow through the first bore; a second sleeve member remotely shiftable within the first bore to move the closure member between its open and closed positions; and a cone member connected to a distal end of the extension member.
  • 26. A well completion including:a well casing in fluid communication with a first hydrocarbon formation; a production tubing disposed within the well casing; gravel packed in an annulus between the well casing and the production tubing; a first packer connected to the tubing and disposed above the first hydrocarbon formation; a first sand screen adjacent the first hydrocarbon formation, connected to the tubing, and establishing fluid communication between the first hydrocarbon formation and the production tubing; a first flow control device connected to the tubing and disposed between the first packer and the first hydrocarbon formation, the first flow control device having a body member and a first sleeve member, the body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore, and the first sleeve member being remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port.
  • 27. The well completion of claim 26, wherein the first end of the body member is positioned above the second end of the body member.
  • 28. The well completion of claim 26, wherein the second end of the body member is positioned above the first end of the body member.
  • 29. The well completion of claim 26, further including a first hydraulic conduit connected between a source of pressurized fluid and the first flow control device.
  • 30. The well completion of claim 29, further including:a second packer connected to the tubing and disposed below the first hydrocarbon formation and above a second hydrocarbon formation; a second sand screen adjacent the second hydrocarbon formation, connected to the tubing, and establishing fluid communication between the second hydrocarbon formation and the production tubing; and a second flow control device connected to the tubing and disposed between the second packer and the first hydrocarbon formation, the second flow control device having a body member and a first sleeve member, the body member having a first bore extending from a first end of the body member and through an extension member disposed within the body member, a second bore extending from a second end of the body member and into an annular space disposed about the extension member, a first valve seat disposed within the first bore, and at least one flow port in the extension member establishing fluid communication between the annular space and the first bore, and the first sleeve member being remotely shiftable within the first bore, and having a second valve seat adapted for cooperable sealing engagement with the first valve seat to regulate fluid flow through the at least one flow port.
  • 31. The well completion of claim 30, further including a second hydraulic conduit connected between the source of pressurized fluid and the second flow control device.
Parent Case Info

This application claims priority and the benefit of U.S. Provisional Application No. 60/108,810 filed on Nov. 17, 1998.

US Referenced Citations (29)
Number Name Date Kind
2090180 Bryant Aug 1937 A
2419313 Byrd Apr 1947 A
2681111 Thompson Jun 1954 A
3095041 Rasmussen Jun 1963 A
3105553 Chisolm Oct 1963 A
3395758 Kelly et al. Aug 1968 A
3662826 Young et al. May 1972 A
3664415 Wray et al. May 1972 A
3741300 Wolff et al. Jun 1973 A
3814181 Young Jun 1974 A
4043392 Gazda Aug 1977 A
4134454 Taylor Jan 1979 A
4201364 Taylor May 1980 A
4253522 Setterberg, Jr. Mar 1981 A
4354554 Calhoun et al. Oct 1982 A
4440221 Taylor et al. Apr 1984 A
4473122 Tamplen Sep 1984 A
4858690 Rebardi et al. Aug 1989 A
4928772 Hopmann May 1990 A
4969524 Whiteley Nov 1990 A
5295538 Restarick Mar 1994 A
RE34758 Farley et al. Oct 1994 E
5377750 Arterbury et al. Jan 1995 A
5579844 Rebardi et al. Dec 1996 A
5609204 Rebardi et al. Mar 1997 A
5730223 Restarick Mar 1998 A
5755286 Ebinger May 1998 A
5803179 Echols et al. Sep 1998 A
5865251 Rebardi et al. Feb 1999 A
Foreign Referenced Citations (2)
Number Date Country
1 077 562 Aug 1967 GB
WO 9610123 Apr 1996 WO
Provisional Applications (1)
Number Date Country
60/108810 Nov 1998 US