Wells – Valves – closures or changeable restrictors – Fluid operated
Reexamination Certificate
1998-07-16
2001-04-24
Dang, Hoang (Department: 3672)
Wells
Valves, closures or changeable restrictors
Fluid operated
C166S227000, C166S240000
Reexamination Certificate
active
06220357
ABSTRACT:
The invention relates to a downhole tool, and particularly relates to a downhole tool having ports therein which can be selectively opened and closed to permit and deny fluid to flow therethrough.
When drilling for oil and gas, in recent years it has been known to drill horizontally through the payzone of the formation, in order to maximise the production available from the well. The result of horizontal drilling is that there may be thousands of feet of production pipe located within the payzone. Conventional production pipe for horizontal wells consists of pre-perforated pipe which is run into the well with an inner string located within the pipe. Circulation of fluid through the inner string assists the placement of the pipe onto the bottom of the well. The inner string also allows the well to be cleaned after drilling by circulating cleaning fluids through the inner string. For this cleaning operation it is useful to have a high cleaning fluid circulation rate to give a turbulent cleaning action.
However, the employment of the inner string reduces the pressure of circulating fluid available because of the inner string's reduced internal diameter when compared to the diameter of the perforated pipe. Also, because the pipe is perforated, the cleaning fluid is circulated in the annulus between the inner string and the perforated pipe, as well as the annulus between the perforated pipe and the wellbore where it is actually required. Another disadvantage is that the cleaning fluid tends to fall to the lower half of the horizontal well, leaving the upper half relatively unwashed.
Where the oil and gas payzone is a sandy formation it is known to use a filter screen in order to prevent the sand from entering the inner bore of the production pipe. Conventional filter screens are either mounted on the outside of the perforated pipe along its length, and sealed at both ends thereto, or alternatively a rigid filter screen is used instead of a perforated pipe.
According to a first aspect of the invention, there is provided a downhole tool having selectively openable ports therein, the tool being actuable between a closed configuration in which the ports are closed, a primed configuration in which the ports are primed for opening, and an open configuration in which the ports are opened.
Preferably, the tool is actuable by downhole fluid pressure located within an inner bore of the downhole tool, and more preferably, the tool is actuable between the configurations by a variation in the downhole fluid pressure.
In a preferred embodiment, the downhole tool comprises a first body member, and a second body member which is concentric with the first body member.
The first aspect of the invention has the advantage that there is no fluid communication between the inner bore and the ports when the ports are closed, and when the ports are open there is fluid communication between the ports of both of the first and second body members and the inner bore.
According to a second aspect of the present invention, there is provided a downhole screen to filter production fluids, the screen comprising a filter portion, and selectively openable ports, the screen being actuable between a closed configuration in which the ports are closed, and an open configuration in which the ports are opened.
Preferably, the screen is actuable to a primed configuration in which the ports are primed for opening, the primed configuration occurring between the closed and open configurations.
Preferably, the screen is actuable by down downhole fluid pressure located within an inner bore of the screen, and more preferably, the screen is actuable between the configurations by a variation in the downhole fluid pressure.
In a preferred embodiment, the screen comprises a first body member and a second body member, the screen being coupled to one of the first or second body members.
Preferably, the first and second body members have at least one port therein, and more preferably, the first body member is movable with respect to the second body member from the closed configuration to the primed configuration to the open configuration.
The second aspect of the invention has the advantage that when the ports are closed there is no production fluid flow permitted from the filter portion to the inner bore, and when the ports are open production fluid flow is permitted from the filter portion through the ports and into the inner bore.
Preferably, a first movement means is provided to move the first body member from the closed to the primed configuration, and preferably, a second movement means is provided to move the first body member from the primed to the open configuration.
Preferably, the first body member is initially locked in the closed configuration by a selective locking device. More preferably, the selective locking device is a shear pin.
Typically, the first movement means is actuated by increasing the pressure of fluid located within the inner bore. Preferably, the first body member has a smaller internal diameter than the second body member, and more preferably, the fluid pressure acts upon the first body member and unlocks the selective locking device.
Typically, the second movement means is actuated by reducing the pressure of fluid located within the inner bore. Preferably, the second movement means comprises a biassing device, and more preferably, the second movement means is adapted to move the first body member in an opposite direction to the direction in which the first movement means is adapted to move the first body member.
Preferably, the first body member is a movable sleeve.
The second body member may be a body. Alternatively, the second body member is a cylinder which is preferably connected to a port in the side wall of a casing tubular.
The first or second body members may comprise a second locking device to lock the first body member in the third configuration.
Preferably, the first body member is formed from a dissolvable material, which may be dissolved by a suitable material which may be an acid solution.
Preferably, the first and second body members each comprise a respective shoulder which make contact to restrict the movement therebetween at the primed configuration, when the first body member is moved from the closed to the primed configuration.
According to a third aspect of the present invention there is provided a method of opening the ports of a downhole tool, the method comprising increasing the pressure of fluid contained within an inner bore of the downhole tool, and subsequently decreasing the pressure of the fluid contained within the inner bore.
According to a fourth aspect of the present invention there is provided a method of opening the ports in a screen, the method comprising increasing the pressure of fluid contained within an inner bore of the screen, and subsequently decreasing the pressure of the fluid contained within the inner bore.
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Carmichael Mark
Howlett Paul
Browning Clifford W.
Dang Hoang
Specialised Petroleum Services Ltd.
Woodard Emhardt Naughton Moriarty & McNett
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