How to replace the worn drill

Bits in underground work after a certain time, scraper blade drill a smaller diameter, shorter, blunt, rock crushing capacity will become weak, progress slowed down. Tags: Geological coring drill bit concave three wings
Bits in underground work after a certain time, scraper blade drill a smaller diameter, shorter, blunt, rock diamond bandsaw blades  crushing capacity will become weak, slowed down progress; cone drill because tooth wear erosion, bearing damage, can cause cone rotation is not flexible or cone stuck, the torque increases, if not promptly fall from the cone accidents will happen; diamond drill due to the heterogeneity caused by the formation of the PDC drill occurred crack, break, out , also makes drilling footage slower. To speed up the whole well drilling speed, must be replaced with the old drill and drill bit is a few hundred meters to several kilometers underground, how to replace the drill rig workers do?
Drilling rig power driven turntable, kelly, drill and drill bit rotates through observation instrument ground rig drill underground work, as consolidated judgment, if that bit has been worn, replace the drill bit should immediately stop drilling . After stopping drilling to  tile cutting blades continue to maintain the drilling fluid circulation for some time, the purpose is to adjust the performance of the drilling fluid and the cuttings suspended in the fluid out of the ground, the loop so that the new wellbore wall remained stable, while also To carry out routine inspections of drilling equipment. Workers use derrick drilling crown block, traveling block and hook, according to the height of the derrick by column (generally composed of two or three drill) from drilling wells up out of all. After the drill column from the discharge order in the derrick, the proposed downhole drill string while continuing to use the drilling pump perfusion fluid annular space, the  concrete cutting blade purpose is to keep the wellbore fluid level does not drop, the wellbore pressure to balance the formation pressure to prevent borehole collapse or underground formation fluid into the wellbore. Meanwhile, we should pay particular attention to the reduced diameter borehole sticking may occur, the operator must be strictly controlled to enhance speed. All within the wellbore drill pipe, drill collars, after starting out, the need to replace the drill will also act out the workers after removing the old drill press fitted with the new drill down to the original column order can be restored after drilling wells .