After the drill bit has been working in the well for a certain period of time, the blade diameter of the scraper bit becomes smaller, shorter, and blunt, and the ability to break rocks will be weakened, and the progress will slow down; the roller cone bit will cause the roller cone due to tooth wear and erosion and bearing damage. Rotation is not flexible or the cone is stuck, which increases the torque. If it is not started in time, the cone falling accident will occur; the diamond bit will crack, break or fall due to the heterogeneity of the formation. , Which also slows down the drilling footage. In order to speed up the drilling speed of the whole well, it is necessary to replace the used drill bit in time. The drill bit is in the well of several hundred meters to several kilometers. How can the driller replace the drill bit?
When drilling, the power of the drill rig drives the turntable, kelly, drill pipe and drill bit to rotate. Observe the working condition of the downhole drill bit through the gauges on the surface of the drill rig. After comprehensive judgment, if the drill bit is deemed worn out, stop drilling and replace it immediately. drill. After stopping drilling, continue to maintain the drilling fluid circulation for a period of time. The purpose is to adjust the performance of the drilling fluid and bring the cuttings suspended in the drilling fluid out of the ground. Routine inspections of drilling equipment are required. Drilling workers use the crane, traveling block and hook on the derrick, according to the height of the derrick according to the column (generally composed of two or three drill pipes) from the well to pull out all the drilling tools. The lifted drill pipe columns are sequentially discharged in the derrick. While the downhole drill string is proposed, the drilling pump should be used to continuously inject the drilling fluid into the annular space. The purpose is to keep the liquid level in the wellbore from dropping, so that the wellbore The pressure can balance the formation pressure to prevent the well wall from collapsing or the fluid in the downhole formation from entering the wellbore. At the same time, special attention should be paid to the sticking that may occur due to the shrinkage of the borehole wall, and the operator must strictly control the lifting speed. After all the drill pipes and drill collars in the wellbore are lifted out, the drill bit that needs to be replaced is also lifted out at the same time. Workers unload the old drill bit and install the new drill bit and descend into the well according to the original column sequence to resume drilling.