Working Principle of Well Drilling Rigs: Five Steps from Surface to Water Source

Working Principle of Well Drilling Rigs: Five Steps from Surface to Water Source

Step 1: Rock and Soil Breaking (Drilling)

Core Action: The drilling rig drives the drill rod and drill bit to rotate (or impact) via a power head, breaking the underground rock and soil into fragments.

Key Elements:

Drilling Pressure: The downward pressure applied.

Torque: The force of rotation.

Impact Force (for hard rock): The high-frequency impact of the down-the-hole hammer.

Purpose: To continuously drill downwards to create a borehole.

Step 2: Cuttings Removal (Cured Parts Removal)

Core Action: The cuttings generated in Step 1 are promptly removed from the bottom of the well and transported to the surface.

Main Methods:

**Mud Circulation (Forward/Reverse Circulation):** Most commonly used. Drilling fluid (mud) is pumped in, carrying the cuttings back to the surface from the annular space between the drill rod and the well wall (or inside the drill rod).

Air Cuttings Removal: High-pressure air is used to blow the cuttings out of the well; commonly used in down-the-hole hammer drilling rigs.

Auger Conveying: The auger directly rotates the cuttings to the surface.

Objective: To keep the wellbore clean, ensuring the drill bit remains in contact with new rock formations, preventing repeated breakage, and guaranteeing drilling efficiency.

Step 3: Wellbore Protection (Screening)

Core Action: To prevent the collapse of the newly drilled, exposed wellbore.

Main Methods:

**Mud Screening:** Drilling fluid forms a thin, tough "mud cake" on the wellbore, balancing formation pressure while its fluid column pressure supports the wellbore.

**Casing Screwing:** In extremely loose formations (such as quicksand), steel casing is immediately run to prevent collapse.

Objective: To ensure the wellbore remains stable and regular during drilling and well completion.

Step 4: Extension (Drill Pipe Connection)

Core Action: Once a drill pipe is fully drilled into the ground, drilling is stopped, and a new drill pipe is connected at the wellhead.

Process: Raise the drill string → Stop and secure the drill → Connect the new drill pipe → Continue drilling.

Objective: To continuously extend the "drive shaft" and "slag removal channel" from the ground to the drill bit, advancing towards deeper target formations.

Step 5: Constructing a Water Well (Well Completion)

Core Action: After reaching the predetermined depth and aquifer, a "permanent pipe" is lowered into the well, and a filtration system is constructed.

Key Procedures:

**Lowering the Well Casing:** The filter pipe with perforations is aligned with the aquifer, connected to the upper solid pipe, and lowered into the well.

**Gravel Filling:** Screened gravel (coarse sand) is filled into the annular space between the filter pipe and the well wall, forming an artificial filter layer.

**Well Washing:** Vigorous flushing and suction using a pump or air compressor removes mud and fine sand from the well until the water is clear.

Objective: To transform the temporary "drill hole" into a permanent "water well" with a stable flow rate and clear water quality.

In summary, these five steps are interconnected: drilling is the initial step, cuttings removal is the cleanup, wall protection is the safeguard, rod extension is the final step, and well completion is the ultimate goal. The work of a drilling rig is to execute these five steps precisely and efficiently to the end, ultimately creating a reliable channel to groundwater for you.