Patent ID: 6688702
Filing Date: 2004-02-10
Classification: E21B,E21C

Abstract:
A borehole mining method comprising:a) driving at least one borehole, having walls, through a production interval so that within said interval said borehole is driven under a low-degree angle &agr; to the horizontal plane, so that &agr;>0, b) insertion of a mining device within said production interval with at least one water jet nozzle, located substantially at the bottom of said mining device, whereby said nozzle creates a water jet, being able to cut rock material over a distance Rc from said borehole, where Rc is a jet cutting reach-radius, c) circulation of a working agent through said mining device and said borehole by its pumping at a controlled flow rate, d) sliding said device along said borehole, e) extraction of rock material by: 1) water jet cutting of said rock material, 2) creating a pregnant slurry, and 3) removing said slurry from said borehole, f) creation of at least one cavern by said extraction and said sliding, by increasing the span between said borehole walls, such that said cavern also has its walls and roof, g) causing a partial or complete collapse of said cavern walls and roof, and h) extension of said cavern by said sliding of said device along said borehole, such that said device travels substantially within said working interval, whereby, while mining, said device is positioned in said borehole such that said nozzle is oriented at an angle &bgr; to a horizontal plane, so that &bgr;>0, where Rc*Cos &bgr; substantially equals to the desired span between said cavity walls, whereby, said slurry is removed from said cavity by a pump, whose intake is installed near the bottom of said mining device, having at least one slurry intake port, located near said water jet nozzle, whereby, said slurry is removed at a rate substantially equal to or exceeding the flow rate of said working agent, whereby, while mining, said slurry level in said cavity is kept near said pump intake port, whereby, said water jet is directed at least partially above said slurry level.