Method for removal of flexible liners from boreholes
OwnerCarl E. Kellerinventor
Life of this patent
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Abstract
A system and method for performing a flexible liner inversion out from a low-permeability borehole. A flexible liner may be installed by eversion down a subterranean borehole to selectively seal the borehole. Such a liner may be removed from the borehole by inverting it up the borehole. Water is added into the borehole beneath the lowest end of the liner, to permit or facilitate inversion of the liner. Water is allowed to flow from the interior of the liner to the borehole space beneath the liner, thereby raising the pressure in the unsealed borehole beneath the liner, and thereby allowing the liner to be further inverted upward. By allowing water to flow from the liner interior to a borehole volume beneath the liner, the need for a long vent or pumping tube is avoided.
Claims22
A method for facilitating removal of a flexible liner from a borehole below the surface of the ground, there being a lower borehole volume, with a borehole pressure therein, beneath a bottom portion of the liner, the method comprising:
- disposing a flexible liner in the borehole, the liner having:
- a closed end;
- and
- a liner interior containing fluid creating a liner pressure, there being a variable pressure differential between the borehole pressure and the liner pressure;
- disposing a port through the liner near the closed end;
- extending a tube into the liner interior from the port;
- regulating, with a pressure relief valve, fluid flow through the tube, the relief valve opening automatically when the pressure differential exceeds a threshold;
- extending a tether from the closed end to the surface, for pulling the liner toward the surface;
- pulling upward on the tether, thereby reducing the borehole pressure and increasing the differential pressure above the threshold;
- and
- allowing the pressure relief valve to open to permit fluid flow from the liner interior through the port toward the lower borehole volume.
A system for facilitating the removal of a flexible liner from a borehole below the surface of the ground, there being a lower borehole volume, with a borehole pressure, beneath a bottom portion of the liner, the system comprising:
- a flexible liner disposed in the borehole, the liner having:
- a closed end;
- and
- a liner interior containing fluid creating a liner pressure, there being a variable pressure differential between the borehole pressure and the liner pressure;
- a port disposed through the liner near the closed end;
- a tube extending into the liner interior from the port;
- a pressure relief valve on the tube to regulate fluid flow therethrough, the relief valve opening automatically when the pressure differential exceeds a threshold;
- a tether, extending from the closed end to the surface, for pulling the liner toward the surface;
- wherein when an upward pulling on the tether reduces the borehole pressure to increase the differential pressure above the threshold, the pressure relief valve opens to permit fluid flow from the liner interior through the port toward the lower borehole volume.
Dependencies are inferred from the claim text.