| 摘要 |
This invention relates to a method and apparatus for positioning a selected liquid at the bottom of a well, such as an oil well, while having in the well at least a string of tubing, a sucker rod pump, a string of sucker rods, and a standing valve, without disturbing the rods, pump, tubing, or standing valve. A bypass conduit or shroud surrounds the wall of the tubing at a point above the pump where there is an opening in the wall of the tubing and is carried down, outside the tubing to a point below the conventional mud anchor, into the inlet of an overpressure relief valve. The outlet of the valve empties into the well annulus. If the normal pressure at the bottom of the tubing due to the head of liquid in the tubing is P, the overpressure valve is set to open at a pressure of P+P1, where P1 is a selected value, such as say 100 psi. At the surface, means are provided to close off the top of the tubing. Means are provided to inject the selected liquid into the top of the tubing at a selected pressure P2 above atmospheric, where P2 may be say 150 psi. This causes the pressure at the bottom of the tubing to rise to P+P2. Since P+P2 is now greater than P+P1, the overpressure valve will open and pass as much liquid as is pumped into the tubing at the surface. A crossflow unit is inserted into the tubing and the shroud at the standing valve to permit the radial flow of well fluids from outside the shroud to the inlet to the standing valve, and to permit the longitudinal flow of liquid down the annulus inside the shroud, to the relief valve.
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