Method for installation or removal of flexible liners from boreholes
View Patent ↗A system and method for performing a flexible liner eversion into, or an inversion out from, a low-permeability borehole. A flexible liner may be installed by eversion down a subterranean borehole in order to selectively seal the borehole. Such a liner may be removed from the borehole by inverting it up the borehole. Water is removed by pumping from the borehole beneath the lowest end of the borehole, to facilitate eversion of the liner. Water is added, by pumping water into the borehole beneath the lowest end of the liner, to permit or facilitate inversion of the liner.
1. A system for facilitating the installation or removal of a flexible liner into or from a subterranean borehole below the surface of the ground, comprising:
a flexible liner evertable down the borehole, the liner having:
a closed end; and
an inverted portion adjacent the closed end;
a port disposed through the liner near the closed end;
a vent tube extending, within an interior of the liner, from the port to the surface;
a tether extending from the closed end to the surface; and
a pump means for moving water to or from the surface, via the port and vent tube, from or to the borehole beneath the inverted portion.
2. A method facilitating installation or removal of a flexible liner into or from a subterranean borehole below the surface of the ground, comprising:
providing a liner with a closed end and an inverted portion adjacent the closed end;
disposing a port through the liner near the closed end;
extending a vent tube within an interior of the liner from the port to the surface;
extending a tether from the closed end to the surface; and
moving water to or from the surface, via the port and vent tube, from or to the borehole beneath the inverted portion.
3. The method of claim 2 further comprising everting the liner down the borehole while moving water, via the port and vent tube, to the surface from the borehole.
4. The method of claim 3 further comprising:
defining an exterior pocket with the inverted portion of the liner;
supporting a flexible conduit within the pocket and below the port;
extending a bottom end of the flexible conduit into the borehole beneath the inverted portion; and
maintaining with the flexible conduit a flow path through the pocket from the borehole beneath the inverted portion of the liner and to the port.
5. The method of claim 4 wherein the step of moving water to the surface comprises pumping water from the pocket via the port.
6. The method of claim 4 wherein the step of supporting a flexible conduit comprises:
connecting a chain to the closed portion of the liner; and
covering the chain with a permeable flexible tubular mesh.
7. The method of claim 6 further comprising:
allowing the chain to reach a bottom of the borehole; and
while everting the liner, allowing the chain to accumulate in a pile on the bottom of the borehole.
8. The method of claim 3 wherein the step of everting the liner down the borehole while moving water to the surface comprises:
deploying at the surface a main reel having a hollow axle;
placing a pump in fluid communication with the hollow axle;
placing the vent tube in fluid communication with the hollow axle;
unwinding the tether and vent tube from the reel while pumping water to the surface via the vent tube and hollow axle.
9. The method of claim 5 wherein the step of pumping comprises peristaltic pumping.
10. The method of claim 5 wherein the step of pumping comprises air-lift-pumping, and further comprising:
placing a connector in the vent tube above the port;
extending an air injection tube from the surface and connected to the connector;
placing the air injection tube in fluid communication with the vent tube via the connector;
allowing the vent tube above the connector to at least partially fill with water from the port; and
injecting air through the injection tube to pump aerated water upward in the vent tube to the surface.
11. The method of claim 5 wherein the step of pumping comprises positive displacement pumping, and further comprising:
placing a connector in the vent tube above the port;
locating a check valve in the vent tube above the port and below the connector;
extending a second tube from the surface and connected to the connector;
placing the second tube in fluid communication with the vent tube via the connector;
allowing the vent tube above the check valve to at least partially fill with water from the port;
injecting air into a top of the vent tube to increase pressure in the vent tube, thereby closing the check valve;
expelling at the surface, via the connector and second tube, water in the vent tube.
12. The method of claim 2 further comprising inverting the liner up the borehole while moving water, via the port and vent tube, to the borehole from the surface.
13. The method of claim 12 further comprising:
defining an exterior pocket with the inverted portion of the liner;
supporting a flexible conduit within the pocket and below the port;
extending a bottom end of the flexible conduit into the borehole beneath the inverted portion; and
maintaining with the flexible conduit a flow path through the pocket from the port and to the borehole beneath the inverted portion of the liner.
14. The method of claim 12 wherein the step of moving water to the borehole comprises pumping water into the pocket via the port.
15. The method of claim 12 wherein the step of inverting the liner up the borehole while moving water to the borehole comprises:
deploying at the surface a main reel having a hollow axle;
placing a pump in fluid communication with the hollow axle;
placing the vent tube in fluid communication with the hollow axle;
winding the tether and vent tube onto the reel while pumping water from the surface via the hollow axle and vent tube.
16. A method facilitating installation removal of a flexible liner from a subterranean borehole below the surface of the ground, comprising:
providing a liner with a closed end and an inverted portion adjacent the closed end;
disposing a port through the liner near the closed end;
extending a vent tube within an interior of the liner from the port to the surface;
extending a tether from the closed end to the surface;
moving water from the surface, via the port and vent tube, to the borehole beneath the inverted portion; and
inverting the liner, with the tether, up the borehole while moving water to the borehole.
17. The method of claim 16 further comprising:
defining an exterior pocket with the inverted portion of the liner;
supporting a flexible conduit within the pocket and below the port;
extending a bottom end of the flexible conduit into the borehole beneath the inverted portion; and
maintaining with the flexible conduit a flow path through the pocket from the port and to the borehole beneath the inverted portion of the liner.
18. The method of claim 17 wherein the step of moving water to the borehole comprises pumping water into the pocket via the port.
19. The method of claim 17 wherein the step of inverting the liner up the borehole while moving water to the borehole comprises:
deploying at the surface a main reel having a hollow axle;
placing a pump in fluid communication with the hollow axle;
placing the vent tube in fluid communication with the hollow axle;
winding the tether and vent tube onto the reel while pumping water from the surface via the hollow axle and vent tube.