Core Process Analysis on Hole Deviation Correction of Rotary Drilling Rig: Guidance, Deflection Rectification and Re-drilling

Causes of deviated holes and early guidance prevention and control

During the construction of rotary drilling rigs, off center hole is a common quality hazard, which is often caused by uneven geology, deviation of drill pipe verticality, and imbalance of drilling speed, which can easily lead to pile displacement and insufficient bearing capacity. The core of preventing and controlling deviated holes in the industry is to do a good job in early guidance. Before construction, the verticality of the drill pipe needs to be calibrated, and the angle of the drilling tool needs to be adjusted based on the geological survey report. In complex geological areas such as soft soil and rock layers, guide casings can be laid in advance, and the trajectory of the drill pipe can be monitored throughout the process to reduce the probability of deviated holes from the source.

Accurate correction: graded disposal to avoid secondary damage

After discovering a deviated hole, it is necessary to classify and handle it according to the degree of deviation, in order to avoid blind correction causing the drill pipe to bend and the hole wall to collapse. Slight deviation (deviation ≤ 3cm) can be gradually corrected by adjusting the angle of the drill rod and drilling at a low speed and constant speed, and monitored in real-time using a spirit level; Moderate deviation can be achieved by backfilling with high-quality clay or gravel, and adjusting the directional drilling after the hole wall stabilizes; Severe deviation requires stopping drilling, cleaning the debris inside the hole, and using directional correction drilling tools to assist in correction to ensure that the verticality of the pile hole meets the specifications.

Heavy drilling process: standardized operation to ensure pile quality

When the deviation of the hole is severe and cannot be repaired through conventional correction, it is necessary to implement the re drilling process and follow industry construction standards throughout the process. Before re drilling, it is necessary to thoroughly clean the collapsed soil and debris in the original hole, reposition the pile position, and calibrate the guiding device; Control the drilling speed during the drilling process, slow down the speed at the junction of soft and hard soil layers, and avoid drilling tool shaking; After the re drilling is completed, the verticality, diameter, and depth of the pile hole need to be checked. Only after passing the inspection can the next process be carried out to prevent quality hazards caused by non-standard re drilling operations.

Process control: Full process monitoring to improve calibration efficiency

The key to correcting the deviation of the rotary drilling rig is full process control, which requires professional monitoring personnel to use equipment such as total stations and level gauges to monitor the verticality of the drill pipe and the deviation of the pile hole in real time. At the same time, optimizing drilling parameters based on geological conditions, selecting suitable types of drilling tools, regularly checking the wear of drill rods and bits, and replacing them in a timely manner to ensure smooth connection between guidance, correction, and re drilling, not only improving correction efficiency but also ensuring the quality of pile construction.