In-situ mining of ores from subsurface formations

Abstract

An in situ method of mining is disclosed. In one non-limiting embodiment, the method includes: defining an ore volume; drilling a large number of vertical boreholes; forming lateral boreholes from at least some of the vertical boreholes; transporting the ore cut during drilling of the vertical and lateral boreholes to a surface location; and separating the ore received at the surface from other materials. Additional ore may be extracted fracturing and/or leaching the formation surrounding the drilled boreholes. The residual ore at the surface may be disposed by pumping it into already drilled boreholes or underground storage facilities.

1 . A method of in-situ mining of ore from below the earth surface without removing overburden, the method comprising:
 defining an ore volume below the surface of the earth;   drilling a plurality of boreholes from a surface location through the ore volume to disintegrates the ore volume, wherein each wellbore is drilled by a rotating a drill bit attached at bottom of a drill string and wherein a fluid is circulated through the drill string and the wellbore fluid returning (“return fluid”) to the surface carries therewith the ore disintegrated by the drill bit; and   processing the return fluid at the surface location to recover a selected element present in the ore in the return fluid.   
     
     
         2 . The method of  claim 1  further comprising defining the ore volume using at least one of: seismic survey of earth subsurface that includes the ore volume; information relating to previously drilled boreholes; and acoustic ranging. 
     
     
         3 . The method of  claim 1 , wherein drilling the plurality of boreholes includes maintaining in place the overburden above the ore volume. 
     
     
         4 . The method of  claim 1 , wherein the plurality of boreholes are drilled using pad drilling, wherein each borehole in the plurality of boreholes is drilled from a common surface location and the ore volume from all the return fluid is processed at the common surface location. 
     
     
         5 . The method of  claim 1 , wherein drilling the plurality of boreholes comprises:
 drilling a plurality of main boreholes; and   drilling one or more lateral boreholes for at least some of the main boreholes.   
     
     
         6 . The method of  claim 1 , the method further comprising:
 fracturing formation surrounding at least some of the boreholes in the plurality of boreholes; and   extracting ore from the fractured formation.   
     
     
         7 . The method of  claim 1  further comprising;
 leaching formation surrounding at least some of the boreholes in the plurality of boreholes to produce fluid that contains the ore; and 
 extracting an element of interest from the fluid that contains the ore to the surface. 
 
     
     
         8 . The method of  claim 1 , wherein the ore field is more than 5000 feet deep and the plurality of boreholes includes at least one hundred boreholes, wherein each borehole is spaced less than one hundred feet from an adjacent borehole. 
     
     
         9 . The method of  claim 1 , wherein each borehole is between five feet and twenty five feet from at least one borehole. 
     
     
         10 . The method of  claim 1 , wherein the plurality of boreholes includes a first plurality of vertical boreholes, each such borehole being larger than 28 inches in diameter; at least one lateral wellbore formed from at least some of the main boreholes, each such lateral bore hole being larger than eighteen inches in diameter. 
     
     
         11 . The method of  claim 1 , wherein the ore volume is an isolated section formed by fracture planes created by fracturing of the earth subsurface. 
     
     
         12 . The method of  claim 1  further comprising identifying an element of interest in the ore volume during drilling of at least one borehole in the plurality of boreholes using one of: a pulsed neutron sensor calibrated for a peak relating to a mineral of interest. 
     
     
         13 . The method of  claim 14 , wherein the element of interest is selected from a group consisting of: copper; uranium; gold; platinum; nickel; and manganese. 
     
     
         14 . The method of  claim 1  further comprising determining quantity of an element of interest from the ore separated from the return fluid. 
     
     
         15 . The method of  claim 1  further comprising maintaining drilling of a particular borehole in the plurality of boreholes a selected distance from any other borehole already drilled. 
     
     
         16 . The method of  claim 15 , wherein maintaining the selected distance comprising using one of: acoustic logging while drilling; and magnetic ranging while drilling. 
     
     
         17 . The method of  claim 1  further comprising disposing ore remaining after processing (“residue”) as one of: pumping the residue with a fluid into one or more boreholes already drilled; pumping the residue with cement into one or more boles already drilled;
 and storing the residue in underground storage units. 
 
     
     
         18 . A method of in-situ mining of an ore from below the earth surface from a vein containing a metal of interest, the method comprising;
 defining the vein containing the metal of interest;   drilling a borehole from a rig site through the vein to disintegrate ore in the vein into cuttings by circulating a fluid through the borehole;   geosteering the drilling of the borehole using an electrical measurements of surrounding the borehole during drilling to maintain the borehole within the vein;   receiving a return fluid from the borehole containing the cuttings;
 separating the cuttings from the return fluid; and 
 processing the cuttings at the rig site to recover the metal of interest from the cuttings. 
   
     
     
         19 . The method of  claim 18 , wherein the electrical measurements are responsive to metallic elements present in the formation surrounding the borehole and the formation in front of the borehole. 
     
     
         20 . A system for in-situ mining of ore from an ore volume below the earth surface without removing overburden, the system comprising:
 a drilling system for drilling a plurality of boreholes from a rig site that uses a fluid to drill the plurality of boreholes and receives a return fluid from each such borehole that includes cuttings of the ore therein;   a separator at the rig site that separates the ore cuttings from the return fluid; and   a processing unit at the rig site that processes the separated ore cutting to recover an element of interest from the ore cuttings.