I. Drill Bit Selection

Match geological conditions

Soft formations (such as shale and sandstone): Choose either a roller cone bit or a PDC (polycrystalline diamond compact) bit. The former is suitable for large diameters and low rotational speeds, while the latter is ideal for high-speed drilling.
Hard formations (such as granite and limestone): Prioritize diamond drill bits or carbide drill bits, which offer excellent wear resistance.
Complex formations (such as those containing gravel or faults): Use hybrid drill bits or custom-designed tools to enhance impact resistance.

Select according to drilling type

Nakai: A standard drill bit will suffice.
Directional/Horizontal Wells: It is necessary to select drill bits with high torque resistance and excellent steering capability, such as PDC drill bits paired with a steering system.
Deep wells/ultra-deep wells: Select drill bits that are resistant to high temperatures and pressures, such as those made from high-temperature alloys or treated with special coatings.

Size and specifications match.

The drill bit diameter must match the dimensions of the drill pipe and casing to prevent sticking or irregularities in the wellbore.
Select an appropriate length based on the designed drilling depth to avoid frequent drill bit replacements.

II. Installation and Debugging

Check the integrity of the drill bit.

Confirm that the drill bit has no cracks, wear, or loose components, especially the cutting teeth and gauge teeth.
Check whether the thread connections between the drill bit and drill rod match to prevent slipping or leakage.

Correct installation

Use specialized tools (such as a drill bit holder) for installation to avoid damage caused by forceful hammering.
Ensure that the drill bit is concentric with the drill rod to prevent uneven wear or excessive vibration.

Debugging parameters

Adjust the drilling weight, rotational speed, and pump rate according to the drill bit type and formation conditions. For example:
PDC drill bit: high rotational speed (100–300 rpm), low drilling pressure (5–15 kN/cm).
Cone bit: low rotational speed (50-100 rpm), high drilling force (15-30 kN/cm).
Avoid parameter fluctuations to prevent the drill bit from overloading or failing.

III. Operating Procedures

Smooth drilling

Maintain stable drilling pressure and rotational speed, and avoid frequent starts and stops or sudden changes in direction.
Reduce the drilling rate at the interface between soft and hard formations to prevent bit chipping or deviation.

Control drilling fluid performance

Adjust the drilling fluid’s density, viscosity, and yield stress to ensure it can effectively carry cuttings, cool the drill bit, and balance formation pressure.
Avoid excessive sand content in the drilling fluid to prevent accelerated wear of the drill bit.

Monitor drill bit condition

Real-time assessment of the drill bit’s operating condition based on logging data (such as torque, drilling rate, and vibration).
If you notice a sudden drop in drilling speed, abnormal torque, or a rise in pump pressure, immediately stop drilling and conduct an inspection.

IV. Maintenance and Care

Regular check-ups

Check the drill bit’s wear condition every time it is drilled to a certain depth (e.g., 50–100 meters), paying particular attention to the cutting teeth, gauge teeth, and nozzles.
Record the drill bit’s usage time, penetration rate, and parameters to provide a basis for subsequent selection.

Cleaning and Lubrication

After drilling is complete, rinse the mud off the drill bit surface with clean water to prevent it from becoming difficult to clean once it has hardened.
Apply rust-preventive oil to metal parts and store them in a dry, well-ventilated area.

Repair and Reuse

A slightly worn drill bit can have its performance restored by grinding the cutting teeth or replacing the nozzle.
Drills that are severely damaged must be scrapped to prevent accidents caused by reuse.

V. Safety Protection

Personal protective

Operators must wear safety helmets, protective goggles, dust masks, and non-slip shoes.
Avoid direct contact with high-temperature drill bits or drilling fluids to prevent burns or chemical corrosion.

Equipment safety

Ensure that equipment such as drilling rigs and pump units are properly grounded to prevent electric leakage.
Regularly inspect the hydraulic system, transmission components, and safety valves to prevent high-pressure leaks or mechanical failures.

Emergency Handling

Develop emergency response plans for incidents such as stuck drill pipes, well kicks, and drill bit failures, and equip with rescue tools (such as fishing jars and impact tools).
Operators must be familiar with the emergency shutdown procedure to ensure a rapid response.

VI. Notes for Special Scenarios

High High-temperature and high-pressure environment

Use high-temperature-resistant materials (such as ceramics and diamond-composite sheets) and a sealed design to prevent thermal deformation or leakage of the drill bit.
Control the drilling fluid temperature to prevent the drill bit from becoming brittle due to excessive temperature differences.

Deep-sea drilling

The drill bit must have corrosion resistance and be suitable for seawater environments.
Consider the impact of water depth on drilling weight and torque, and adjust operational parameters accordingly.

Unconventional Oil and Gas Development

The development of shale gas, coalbed methane, and other resources requires multi-stage reaming drill bits to increase the production per well.
During drilling, the wellbore trajectory must be strictly controlled to avoid deviation from the target formation.