Operation Procedure of Truck-mounted Reverse Circulation Power Head Drilling Rig

Preparation before Construction

• Site Survey and Leveling: After arriving at the construction site, conduct a detailed survey of the site to ensure that the ground is firm and level and can bear the weight of the drilling rig and its supporting equipment. If the site is not level, leveling work is required to prevent the drilling rig from tilting or sinking during the operation.
• Equipment Inspection and Commissioning
  • Check the chassis of the drilling rig, including tire pressure (if it is a tire-mounted chassis), suspension system, and braking system, etc., to ensure that the chassis is in good condition and can operate and travel normally.
  • Check the diesel engine, check whether the fuel, oil, and coolant levels are normal, whether the belt tension is appropriate, whether there are any loose connections, start the engine, listen to whether the running sound is normal, and check whether the various parameters on the instrument panel are normal.
  • Check the hydraulic system, check the hydraulic oil level, check whether there is any leakage in the hydraulic pipeline, and whether each hydraulic component (such as hydraulic pump, hydraulic motor, hydraulic cylinder, etc.) works normally. Start the hydraulic system and operate each hydraulic control handle to observe whether the corresponding actuating elements operate accurately and smoothly.
  • Check the electronic control system, check whether the wire connections are firm, whether each electrical component (such as solenoid valve, sensor, controller, etc.) works normally, and whether the electrical instruments on the instrument panel display accurately.
  • Check the vacuum pump, check the vacuum pump oil level, check whether the inlet and outlet pipelines of the vacuum pump are connected tightly, start the vacuum pump, and check whether its vacuum degree can meet the requirements.
  • Check the drill tower, check whether the structure of the drill tower is stable, whether the bolts at each connection part are tightened, whether the verticality of the tower frame meets the requirements, whether the wire rope is worn or broken, and whether the pulley rotates flexibly.
• Tool and Material Preparation: Prepare appropriate drilling tools, such as drill pipes and drill bits (select appropriate types of drill bits, such as roller bits and drag bits, etc. according to the formation conditions), and check their quality and integrity. Prepare other tools required for construction, such as wrenches, pliers, screwdrivers, etc., as well as bentonite, additives, and other materials for mud preparation (if mud reverse circulation is adopted).
• Positioning and Installation
  • According to the design requirements, accurately drive the drilling rig to the drilling position, and use the vehicle-mounted positioning system (if available) or measuring instruments for positioning to ensure that the drilling position is accurate.
  • Lower the outriggers of the drilling rig and adjust the height of the outriggers to keep the chassis of the drilling rig level. For drilling rigs with hydraulic outriggers, control the lifting and lowering of the outriggers by operating the hydraulic handle, and observe the level gauge at the same time to ensure that the chassis level error is within the allowable range.
  • Erect the drill tower. During the erection process, pay attention to observing the operation of each part of the drill tower to prevent jamming or collision. After the drill tower is erected, check its verticality again and make fine adjustments if necessary.

Drilling Operation

• Initial Drilling
  • Install the drill bit at the front end of the drill pipe, and slowly lower the drilling tool to the ground through a winch or other lifting device to make the drill bit contact the formation.
  • Start the diesel engine, drive the hydraulic system, operate the power head rotation control handle to make the power head drive the drilling tool to rotate at a low speed (generally 10 – 30 revolutions per minute).
  • Start the vacuum pump to establish a reverse circulation channel so that the cuttings can be discharged in time. For air reverse circulation, start the air compressor and adjust the air pressure to an appropriate range; for mud reverse circulation, start the mud pump to circulate the mud in the borehole.
  • Slowly operate the feed handle to make the drilling tool gradually drill into the formation, and control the drilling speed. The initial drilling speed should not be too fast, generally about 0.5 – 1 meter per hour, to prevent the drill bit from deviating or being damaged.
• Normal Drilling
  • As the drilling depth increases, adjust the drilling parameters reasonably according to the formation change. For example, in soft formations, the rotational speed (generally 30 – 60 revolutions per minute) and drilling speed (generally 1 – 3 meters per hour) can be appropriately increased; in hard formations, the rotational speed (generally 10 – 30 revolutions per minute) is reduced, and the drilling pressure is increased (by adjusting the power head feed pressure), but the drilling speed should be correspondingly slowed down (generally 0.5 – 1.5 meters per hour).
  • Closely observe the cuttings return situation of the borehole, and judge the formation change through the shape, color, and particle size of the cuttings return. If the cuttings return is abnormal, such as a large amount of rock powder appears, or the cuttings return volume suddenly decreases or increases, etc., stop drilling in time, analyze the cause and take corresponding measures.
  • Regularly check the wear of the drilling tools, especially the degree of wear of the drill bit. When the drill bit is severely worn and affects the drilling efficiency or borehole quality, it should be pulled out and replaced in time.
  • Pay attention to observing the working status of each system of the drilling rig, including the oil temperature, water temperature, and oil pressure of the engine, the pressure and oil temperature of the hydraulic system, the vacuum degree of the vacuum pump, etc. If any abnormality is found, such as the engine emitting black smoke, the hydraulic system leaking oil, the vacuum pump suction insufficient, etc., stop the machine immediately for inspection, and continue drilling after troubleshooting.
• Adding Drill Pipes
  • When the drill pipe drills to a certain depth and the remaining drill pipe length is not enough to continue drilling, it is necessary to add drill pipes. First, stop drilling, lift the power head to a certain height to make the drill bit leave the bottom of the hole by a certain distance (generally 0.5 – 1 meter), and then stop the power head rotation and the reverse circulation system.
  • Operate the drill pipe clamp to clamp the drill pipe in the hole to prevent it from sliding down. Lift the power head to an appropriate height through a winch or other lifting device to facilitate the addition of a new drill pipe.
  • Connect the new drill pipe firmly with the drill pipe at the lower end of the power head on the ground. Threaded connection can be used, and an appropriate amount of thread sealant should be applied during connection to ensure a tight connection without water leakage or air leakage (for air or mud reverse circulation).
  • Slowly lower the power head to make the newly connected drill pipe enter the borehole. When the lower end of the new drill pipe approaches the clamp, release the clamp, continue to lower the power head to make the drill bit contact the bottom of the hole, restore the reverse circulation system and the power head rotation, and continue drilling.

Completion of Drilling and Hole Cleaning

• Final Hole Determination: According to the designed drilling depth, when the drilling reaches the predetermined depth, stop drilling and conduct the final hole determination. Measure the length of the drill pipe or use a measuring rope to measure the hole depth to ensure that the drilling depth meets the design requirements. At the same time, conduct a preliminary inspection of the borehole quality, such as the hole diameter and verticality. If any problems are found, take remedial measures in time.
• Hole Cleaning Operation
  • Use the reverse circulation method for hole cleaning, keep the vacuum pump or mud pump working continuously, and fully discharge the rock debris, sediment, and other impurities at the bottom of the hole until there are basically no obvious particles in the returned medium (air, mud, etc.). The hole cleaning time depends on the drilling depth, formation conditions, and cuttings return situation, generally ranging from 30 minutes to several hours.
  • During the hole cleaning process, the drilling tool can be moved up and down appropriately to facilitate the discharge of sediment, but the movement range should not be too large to prevent damage to the hole wall.
  • For mud reverse circulation hole cleaning, the mud performance can be adjusted appropriately, such as reducing the mud specific gravity and viscosity, to improve the hole cleaning effect, but it is necessary to ensure the stability of the hole wall.

Pulling out the Drill Pipe and Equipment Withdrawal

• Pulling out the Drill Pipe Operation
  • After the hole cleaning is completed, stop the reverse circulation system and the power head rotation, and lift the power head to a certain height above the hole opening to make all the drilling tools leave the borehole.
  • Operate the drill pipe clamp to clamp the uppermost drill pipe, and then slowly lift the drilling tool through a winch or other lifting device. Each time the drilling tool is lifted a certain distance (generally 3 – 5 meters), remove the drill pipe and place it neatly in the designated position until all the drilling tools are pulled out of the borehole.
• Equipment Dismantling and Arrangement
  • Lower the drill tower and dismantle each part of the components in accordance with the dismantling sequence of the drill tower and store them properly. During the dismantling process, pay attention to protecting the components of the drill tower to prevent collision damage.
  • Shut down the diesel engine, arrange the pipelines and wires of the hydraulic system, electronic control system, and other equipment, and fix them well to prevent damage during transportation.
  • Retract the outriggers of the drilling rig, install the drilling rig and its supporting equipment on the transport vehicle, and fix them to ensure that there will be no movement or collision during transportation.
• Site Cleaning: Clean up the construction site, tidy up the remaining materials, tools, etc., and transport them away from the site. Clean up the mud, rock debris, and other waste around the borehole and dispose of them in accordance with environmental protection requirements to restore the site to its original state.