Wells – Means for perforating – weakening – bending or separating pipe... – With disparate below ground feature
Reexamination Certificate
1997-11-19
2001-02-06
Dang, Hoang (Department: 3672)
Wells
Means for perforating, weakening, bending or separating pipe...
With disparate below ground feature
C175S004540
Reexamination Certificate
active
06182750
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to the field of performing downhole functions in a well, and is particularly applicable to downhole well completion tools.
In completing a product recovery well, such as in the oil and gas industry, several downhole tasks or functions must generally be performed with tools lowered through the well pipe or casing. These tools may include, depending on the required tasks to be performed, perforating guns that ballistically produce holes in the well pipe wall to enable access to a target formation, bridge plug tools that install sealing plugs at a desired depth within the pipe, packer-setting tools that create a temporary seal about the tool and valves that are opened or closed.
Sometimes these tools are electrically operated and are lowered on a wireline, configured as a string of tools. Alternatively, the tools are tubing-conveyed, e.g. lowered into the well bore on the end of multiple joints of tubing or a long metal tube or pipe from a coil, and activated by pressurizing the interior of the tubing. Sometimes the tools are lowered on cables and activated by pressurizing the interior of the well pipe or casing. Other systems have also been employed.
Typically, ballistic tools are not “armed” (i.e., not yet configured to fire upon receipt of a hydraulic or electric stimulus) until just before being placed in the well, in order to avoid accidental firings at surface. Once armed, very high safety standards must be maintained to avoid potentially deadly premature firings until the tool is safely below ground. Even after the armed tool has been lowered into the well, an accidental, premature firing can result in costly well damage.
SUMMARY OF THE INVENTION
In one aspect of the invention, a downhole device for performing a function in a well has a series of dedicated hydro-mechanical locks that prevent occurrence of the function until desired. The hydro-mechanical locks are each capable of being released directly by a respective elevated hydraulic activating pressure condition and are constructed and arranged for sequential operation such that a lock in the series cannot be released until after the hydraulic pressure conditions required to release any preceding locks in the series have occurred.
In one embodiment, the device is in the form of a self-contained downhole device for controlling the occurrence of the function. In this embodiment, the device includes a downhole housing and a port in the housing in hydraulic communication with a remote hydraulic pressure source via the well by pressure-transmitting structure such as casing or tubing in the well.
In some embodiments, the series of hydro-mechanical locks comprises a set of one or more displaceable elements associated with a common hydraulic actuator, the actuator constructed and arranged to displace the elements sequentially. In some cases the actuator is responsive to an increase in hydraulic pressure to advance to engage an element and to a subsequent decrease in hydraulic pressure to move the element from a locking to an unlocking position.
Some preferred embodiments contain one or more of the following features: the actuator has a piston; the actuator is biased to a first position by a spring, the activating pressure condition moving the actuator to a second, activated position; the elements each comprises a ring, which in some embodiments is resiliently radially compressed, in a locking, unreleased condition, within a first bore of a lock housing; the actuator has a ring gripper for moving the ring; the lock housing has a second, larger bore into which the ring is movable to an unlocking, released position; the ring has an engageable cam surface; the gripper has a finger with a cam surface for engaging the cam surface of the ring, and in some instances a lift formation for lifting any previously released rings to enable the disengagement of an engaged ring from the cam surface of the gripper.
In some embodiments of the invention, the spring comprises a compressible fluid which is compressed in a first chamber by said actuator. In a particularly useful arrangement, the device also has an orifice for restricting a flow of the compressible fluid from the first chamber to a second chamber, enabling the respective activating pressure condition to cause the actuator to compress the fluid in the first chamber. In some instances the device has a third chamber and a floating piston disposed between the second and third chambers, the floating piston containing a one-way check valve constructed to enable flow from the second chamber to the third chamber. In this arrangement the construction of the floating piston advantageously enables oil within the first and second chambers to expand at higher temperatures.
In another embodiment, the series of hydro-mechanical locks comprises one or more valves, each valve arranged to be openable to a released condition in response to an activating hydraulic pressure condition. In a current arrangement, each of the valves has an inlet to receive activating pressure, and an outlet blocked from the inlet until after a respective activating pressure condition has occurred. In some arrangements, the outlet of the valve is hydraulically connected to an inlet of a pressure-activated tool.
In a particularly useful configuration, the valve is constructed to delay opening for a predetermined amount of time after the occurrence of a respective activating pressure condition. This delay time enables the inlet pressure condition to the valve to be reduced before the valve opens. In this manner, the opening of an upper valve in a series of valves does not immediately open a lower valve, enabling a series of such valves to be independently, sequentially opened by a sequence of activating pressure conditions.
Some configurations may have one or more of the following features: the valve has a piston that forces a fluid through an orifice to expose a port to open the valve; and the delay time between the occurrence of the respective activating pressure condition and the opening of the valve is determined at least in part by the size of the orifice.
In another aspect of the invention, a string of tools for performing downhole functions in a well includes a number of functional sections arranged in a physical order within the string along a string axis. At least one of the sections has a downhole device with a series of dedicated hydro-mechanical locks that prevent occurrence of an associated function. The hydro-mechanical locks are each capable of being released directly by a respective elevated hydraulic activating pressure condition, and are constructed and arranged for sequential operation such that a lock in the series cannot be released until after the hydraulic pressure condition required to release any preceding lock in the series has occurred.
In a particularly advantageous configuration, at least three of the sections each have such a device, the string being arranged and configured to perform the functions in an order other than the physical order of the sections along the axis.
In a preferred embodiment, the sections are constructed to enable activating pressure conditions to be applied simultaneously to all of the functional sections having the devices.
In some useful configurations, a first device in the string has at least one fewer dedicated hydro-mechanical locks than a second device in the string, the actuating pressure conditions for releasing the locks of the first and second devices being correlated such that pairs of locks of the first and the second devices are simultaneously released, resulting in all locks being released in the first device while a lock remains unreleased in the second device.
In another aspect of the invention, a downhole device for performing a function in a well has an actuator arranged to move along an axis in response to an activating pressure condition, an operator engageable by the actuator and arranged to cause the function to be performed when moved, and at least one lock element engageable by the actuato
Edwards A. Glen
Huber Klaus B.
Dang Hoang
Schlumberger Technology Corporation
Trop Pruner & Hu PC
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