Wells – Processes – Placing or shifting well part
Reexamination Certificate
2000-03-01
2002-05-28
Neuder, William (Department: 3672)
Wells
Processes
Placing or shifting well part
C166S386000, C166S332800, C166S334100
Reexamination Certificate
active
06394187
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates generally to well service equipment and, in particular, to a formation protection flapper valve assembly for limiting the loss of completion fluid after a service operation has been completed.
2. Description of Related Art
Numerous operations are performed during the drilling and maintenance of subterranean wells that require the introduction of various fluids into the well for specific purposes. For example, in a gravel pack operation a service seal unit mounted on a work string is used to route service fluid along various passages. Such fluids as acids, cements, polymers, and sand-filled liquids may be injected into the formation or into the outer annulus between a sand screen and a perforated well casing. After the various operations are performed, completion fluids are introduced into the well to displace the service fluids that were used to perform the various operations. Once the completion fluid introduction operation has been completed, the apparatus used for the operation must be removed along with the tubular work string carrying the apparatus. Because substantial quantities of completion fluid are usually still contained within the apparatus and work string upon completion of the operation, this fluid will be lost and spilt into the formation when the work string is removed. The completion fluid is costly and will contaminate the formation if it is not contained. Therefore, there is a need for an apparatus or method for containing the completion fluid while the work string is removed and another apparatus for a further operation is being installed.
Several methods have been developed for preventing the completion fluid from running into the formation. One method is to spot a gel material in the bore as the work string is withdrawn in order to close the liner to fluid flow and protect the formation from the pressure of completion fluid.
Another method used for containing completion fluids is that of an automatically operating flapper valve. Such valves have been conventionally mounted on a screen support sub between the screen and the packer for pivotal movement from an upright, open bore position, to a horizontal, closed bore position. The flapper valve is propped open in the upright position during the various operations and when the work string and the apparatus are pulled out, the flapper valve is moved into the horizontal position against the valve seat, usually by a biasing mechanism. The closed valve keeps the completion fluid contained above the valve until another tubing string is inserted into the well. The conventional valves are frangible so that the closure may be forcibly opened by either hydraulic pressure or an impact force.
Another method is to use two flapper valves that may be independently operated. The dual flapper valves are closed and fractured independently of each other in order to accommodate gravel pack operation, a well logging operation, and a completion fluid recovery operation. The lower flapper valve is propped open by the wash pipe during a gravel pack operation and closes when the work string is removed. The lower closure plate is fractured when the well logging operation is begun, while the closure plate of the upper flapper valve is held open by a prop sleeve. After the well logging operation is complete, the prop sleeve is retracted and the upper flapper valve closes. Then the work string is removed and the completion fluid is recovered. The upper closure plate is fractured when the production operation is begun.
An illustration of a prior art implementation of this method is shown in
FIGS. 1A and 1B
. The upper and lower flapper valve assemblies
10
A,
10
B in combination define a dual flapper valve assembly, with each flapper valve being selectively closed and capable of being fractured independently of the other to accommodate separate well service operations. Each flapper valve assembly includes a valve body
66
A,
66
B that is mounted on a connector sub
68
A,
68
B, respectively. Frangible valve closure plates
70
A,
70
B are pivotally mounted onto the respective valve bodies for sealing engagement against an annular, elastomeric valve seat
72
A,
72
B, respectively. Each annular valve seat is formed of a compressible elastomeric material and is concentric with the cylindrical bore
74
A,
74
B of the valve body. Each closure plate has an annular, beveled surface
75
A,
75
B for producing close sealing.
The valve closure plate
70
B is pivotally mounted onto the valve body
72
B by an elastomeric hinge
76
B. The valve closure plate
70
A is likewise pivotally mounted onto the valve seat
72
A by an elastomeric hinge
76
A.
Each valve body
66
A,
66
B is mounted onto the connector subs by screw fasteners
78
A,
78
B. Each valve body is sealed against a connector sub
68
A,
68
B by an annular elastomeric seal
80
A,
80
B, respectively. The elastomeric hinges
76
A,
76
B are anchored onto the valve body
72
A,
72
B by screw fasteners
78
A,
78
B, respectively. Each elastomeric hinge includes a tubular metal insert
82
A,
82
B for receiving the threaded fasteners
78
A,
78
B, respectively.
The frangible closure plate
72
B of the lower flapper valve
10
B has an elastomeric bumper
84
which engages the wash pipe
46
and is propped open during the gravel pack operation when the wash pipe is extended through the packer. According to this arrangement, the lower flapper valve
10
B is closed automatically upon withdrawal of the wash pipe
46
as shown in FIG.
1
B. The closure plate
70
B of the lower flapper valve
10
B remains closed against the valve seat
72
B while the service fluids are displaced by heavy completion fluids. Thus, after the reverse-flow circulation-out operation has been performed, and the well annulus has been filled with heavy completion fluid, the service tool and wash pipe can be withdrawn without loss of the completion fluid.
During the course of the gravel pack operation, the lower flapper valve
10
B is held in open valve position by the wash pipe
46
. Upon withdrawal of the wash pipe, the valve closure element
70
B moves automatically to the closed and sealed position as shown in
FIG. 1B
, thereby containing the completion fluid and preventing its release into the formation. With the flapper valve
10
B thus protecting the formation, clean-up operations, for example, cleaning up the well bore, can be carried out and the completion fluid can be recovered with the wash pipe
46
disengaged. After the completion fluid has been recovered, the work string may then be retrieved from the well and a production tubing string may be run into the well in its place. Such operations may take several days, during which time the formation is protected by closure of the lower flapper valve
10
B. Upon completion of the clean-up operations and recovery of the completion fluid, a production string is inserted into the well and is sealed against the upper packer to provide for production from the formation to the surface. Before the onset of production operations, however, the lower flapper valve
10
B must be fractured to open the flow passage in the screen support sub so that formation fluids can be lifted to the surface.
Each valve closure member
70
A,
70
B is constructed so that it can be ruptured or otherwise destroyed in response to a mechanical or hydraulic opening force. Each flapper valve closure member is preferably constructed of a frangible material such as tempered glass, for example, a borosilicate glass having strength sufficient to withstand the expected operating pressures, which will rupture under an opening force to provide a fully opened bore through the production string. The frangible valve closure member is designed to rupture in response to the build-up of hydraulic pressure or in response to a downward penetrating impact force applied by a wire line tool or a drop bar. Preferably, each flapper valve closure member is constructed of tempered glass rather than ceramic or metal, which
Butler Paul E.
Dickson Rennie L.
Vinzant Michael V.
Carstens David W.
Halliburton Energy Service,s Inc.
Imwalle William M.
Neuder William
LandOfFree
Flapper valve assembly apparatus and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flapper valve assembly apparatus and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flapper valve assembly apparatus and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2904588