US 4,067,617 A · Subterranean drilling and slurry mining

Abstract

Subterranean slurry mining with one or more mining nozzles which, during mining, directs a high pressure jet of liquid into a granular ore matrix to reduce the ore to a slurry which is thereafter pumped to the surface by an eductor pump including a high pressure eductor nozzle. The drilling and mining apparatus includes several different types of hydraulic control systems which operates at or below system pressure and allows the apparatus to be changed between the mining and a drilling mode. During drilling, the liquid is directed through an open foot valve and drill bit into the well cavity being drilled to wash the cuttings to the surface at which time the mining and eductor nozzles are closed. During mining the control systems close the foot valve and control the opening of the mining nozzle (or nozzles) and eductor nozzle. When the control system includes one or more control conduits that extend to the surface, the system may be used to modulate the eductor nozzle, and depending upon the control system being used to selectively open or close the mining nozzle, thereby controlling the pressure or draw-down in the cavity. Self-activating control systems are disclosed and are responsive to differences between system pressure and cavity pressure when the foot valve is closed to modulate the eductor nozzle. Other self-activating control systems may be used to selectively open and close a pair of mining nozzles without modulating the eductor nozzle, or with provision for modulating the eductor nozzle.

Claims30

Dependent claims

A method of drilling and slurry mining granular ore from a deep well cavity with an apparatus which includes one or more mining nozzles, an eductor nozzle, and a foot valve in a tool string having a liquid inlet passage and a slurry discharge passage therein, said tool string defining a system pressure zone above said foot valve and a cavity pressure zone below said foot valve whose pressure varies from slightly below system pressure to cavity pressure, depending upon the velocity of liquid flowing through the foot valve and the position of the foot valve:

the method comprising the steps of directing system pressure against the mining nozzle and the eductor nozzle in a direction tending to open the nozzles and against the foot valve in a direction tending to close the foot valve, resiliently urging the mining nozzles and eductor nozzles toward their closed positions and the foot valve toward its open position, directing a liquid at a drilling system pressure and capacity into the tool string and through the foot valve to flush cuttings to the surface during drilling, increasing the system pressure and capacity above their drilling conditions at the start of mining for creating a sufficient change over pressure and pressure drop across the foot valve to close the foot valve thereby providing a low cavity pressure below the foot valve that is substantially less than said system pressure, restricting the rate of closure of the foot valve, venting a portion of the mining nozzle to a pressure below system pressure causing the opposing mining system pressure to exceed said resilient force plus said low pressure acting on the mining nozzle thereby opening the mining nozzle, and venting a portion of the eductor nozzle to allow the opposing mining system pressure to exceed said resilient force and said low pressure acting on the eductor nozzle thereby opening the eductor nozzle.

In a method of drilling and slurry mining granular ore from a deep well cavity with an apparatus which includes one or more mining nozzles and a foot valve in a tool string having a liquid inlet passage and a slurry discharge passage therein, said tool string defining a system pressure zone above said foot valve and a cavity pressure zone below said foot valve whose pressure varies from slightly below system pressure to cavity pressure, depending upon the velocity of the liquid through the foot valve and the position of the foot valve:

the method comprising the steps of directing system pressure against the mining nozzle in a direction tending to open the nozzle and against the foot valve in a direction tending to close the foot valve, resiliently urging the mining nozzle toward its closed position and the foot valve toward its open position, directing a liquid at a drilling system pressure and capacity into the tool string and through the foot valve to flush cuttings to the surface during drilling, increasing the system pressure and capacity above their drilling conditions at the start of mining for creating a sufficient change over pressure and pressure drop across the foot valve to close the foot valve thereby providing a low cavity pressure below the foot valve that is substantially less than said system pressure, venting a portion of the mining nozzle to a pressure below system pressure causing the opposing mining system pressure to exceed said resilient force plus said low pressure acting on the mining nozzle thereby opening the mining nozzle causing liquid to flow therefrom and reduce the granular ore to a slurry.

Dependencies are inferred from the claim text.

Subterranean drilling and slurry mining

Life of this patent

Subterranean drilling and slurry mining

Life of this patent

Abstract

Claims30