Directional drilling advanced in recent years as oil companies sought to exploit hard-to-reach deposits. That technology allowed technicians on the surface to guide drills precisely to the mine tunnels and rooms to establish communication, provide relief supplies, and eventually drill an escape. Brandon Fisher, who invented the drill bit used to bore out the elevator shaft used by the miners today, says that the 28-inch hole was relatively small by his standards – his company's bits can drill holes of almost 10 feet in diameter. With the hole drilled, long-established techniques could be employed – such as lowering a metal capsule and hauling it to the surface with a winch.
Reuters/stringer
