Wells – Processes – Placing or shifting well part
Reexamination Certificate
1999-02-01
2001-12-11
Dang, Hoang (Department: 3672)
Wells
Processes
Placing or shifting well part
C166S066700, C166S332100, C166S332600, C251S319000
Reexamination Certificate
active
06328112
ABSTRACT:
BACKGROUND
The invention relates to valves used to control fluid flow in wells.
In a wellbore, one or more valves may be used to control flow of fluid between different sections of the wellbore. These different sections may include multiple completion zones in vertical or deviated wells or in multilateral wells. Various types of valves are available, including ball valves, sleeve valves, flapper valves and other types of valves.
Conventional sleeve valves are mechanically actuated with a tool lowered into production tubing at the end of a slickline or coiled tubing, for example. To actuate the sleeve valve between open and closed positions, the slickline or coiled tubing is raised or lowered at the well surface. Referring to
FIG. 1A
, portions of a sleeve valve
30
and production tubing
32
are illustrated. The sleeve valve
30
includes a longitudinally moveable concentric sleeve having a port
38
that when aligned with a corresponding port
34
in the production tubing
32
allows fluid flow between the bore
33
and the exterior of the production tubing
32
. As illustrated, when the sleeve valve
30
is in the closed position, the body of the concentric sleeve and O-ring seals
36
and
37
block fluid flow through the production tubing port
33
. The seals
36
and
37
typically are made of an elastomer material.
Intervention required to operate such mechanically actuated sleeve valves makes them relatively expensive and time-consuming to operate. Because of the depths of some reservoirs, a long slickline may be needed to run an actuation tool downhole. Further, in horizontal or highly deviated wells, the process of moving the sleeve may be very expensive because of the need for coiled tubing or other more complicated actuating mechanisms to carry the tool to the sliding sleeve. Such problems are exacerbated in a well that uses subsea technology, with no platform over the well, in which case an intervention vessel may be needed to access the sea floor to run a tool downhole to actuate the sleeve valve. Further, after a sleeve valve has been exposed to a wellbore environment for some time, the sleeve may be stuck or rendered more difficult to operate due to corrosion and debris. If the sleeve is stuck, then a mechanical jarring device may have to be run into the production tubing to jar the sleeve loose.
In addition, the hydraulic seals formed of an elastomer material may add additional drag to movement of the sleeve valve, rendering its operation even more difficult. Further, due to the presence of the elastomer seals, reliability may be an issue if the sleeve valve is left downhole for a long period of time due to exposure to caustic fluids.
More recently, remotely actuatable sleeve valve systems have been developed. Referring to
FIG. 1B
, a remotely actuatable sleeve valve system positioned downstream from a packer
20
is illustrated. As illustrated, the sleeve valve system is positioned adjacent a reservoir
12
in a section of a wellbore. A production tubing
10
may be extended to the reservoir
12
, which may contain oil or gas, to receive fluid from the reservoir
12
for production to the surface. A sliding sleeve valve
14
, longitudinally moveable between open or closed positions, may be mounted either outside the production tubing
10
as shown in
FIG. 1B
or inside the production tubing as in FIG.
1
A. In the open position, ports
15
of the sleeve valve
14
are aligned to corresponding ports in the production tubing
10
.
To operate the sleeve valve
14
, it may be coupled to an actuator
16
controlled by an actuator drive system
18
, which typically may be a linear actuator. Rotary actuators may also be used. In addition, the actuator
16
may be controlled hydraulically or electrically. In response to remotely transmitted electrical signals or hydraulic actuation, the actuator drive system
18
causes longitudinal movement of the actuator
16
.
Sleeve valves may require relatively large forces to overcome the drag from hydraulic seals in the valve, particularly when the sleeve valve is exposed to high pressure. In addition, a sleeve valve may require a relatively long stroke to move between a fully open position and a fully closed position. As a result of the relatively large forces and long strokes employed to actuate a sleeve valve, an actuator (such as the actuator system
18
in
FIG. 1B
) employed to actuate the sleeve valve may need to be relatively high powered. To provide such high power, sophisticated electronic circuitry may need to be employed and relatively large diameter electrical cables may need to be run from the surface to the valve actuator mechanism.
Thus, a need arises for an improved valve system for downhole use in wells.
SUMMARY
In general, according to one embodiment, a valve assembly includes a seat having at least an opening and a first surface. A cover has a contact surface that is slideably and sealingly engaged to the first surface of the seat to form a seal when the contact surface completely covers the at least one opening.
Other features will become apparent from the following description and from the claims.
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Dang Hoang
Schlumberger Technology Corp
Trop Pruner & Hu PC
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