METHOD FOR FEEDING ROCK-CUTTING TOOL IN WELL Russian patent published in 1997 - IPC

FIELD: well drilling. SUBSTANCE: during lowering of rock-cutting tool into well, value of drilling mud flow rate pumped through drilling hose is periodically changed. At maximum flow rate, the upper end of drill string is fixed to prevent axial displacements. During reduction of drilling mud flow rate, feed of upper end of drill string is started towards hole bottom. Prior to lifting of hose, lowered inside it are hinged arms which catch the hose lower end. In drilling, drilling mud flow rate is increased from minimum to maximum values with upper end drill string being fixed in axial direction up to reduction of power value consumed by downhole motor. It is limited by permissible elongation of drilling hose. Before beginning of reduction of drilling mud flow rate, feed of upper end of drill string is started. It is ended upon reaching the maximum value of drilling mud flow rate, not earlier, Value of feed of upper end of drill string is not less than value of footage per bit for the previous cycle of extension of drilling hose. EFFECT: higher reliability of work in horizontal and directional wells, prevented inelastic deformations of drilling hose in its lifting and provided preset drilling conditions. 2 cl, 3 dwg