Analysis of Three Core Technologies of Drilling Rigs

Analysis of Three Core Technologies of Drilling Rigs

I. Rotary Drilling

Working Principle: Utilizing a hydraulic system to provide powerful downforce and torque, the drill bucket with teeth at the bottom rotates and cuts the formation. After the drill bucket is filled with soil and rock, it is pulled out of the hole via a telescopic drill rod to unload the cuttings, and the cycle continues until the designed depth is reached. Mud (stabilizing fluid) is often used for wall protection.

Core Features:

Advantages: Extremely high efficiency; fastest drilling speed in suitable formations; good hole quality, regular hole walls, and less sediment; environmentally friendly, clean construction site; high degree of automation, labor-saving operation.

Disadvantages: Low efficiency and high wear in hard bedrock and large boulder layers; expensive equipment; demanding requirements for wall protection in extremely unstable formations (such as thick quicksand).

II. Percussion Drilling

Working Principle: Relying on a winch system, a heavy drill bit (impact hammer) is lifted to a high position and allowed to fall freely, using impact kinetic energy to break rocks or compact soil layers. The cuttings are then removed from the hole using a suction drum.

Core Features:

Advantages: Extremely strong rock-breaking ability, highly effective against hard rock and large boulders; simple equipment structure, low purchase and maintenance costs; very wide adaptability to geological formations.

Disadvantages: Low efficiency, slow cycle operation speed; poor hole quality, prone to hole deviation, staggered holes, and excessive sediment; poor environmental performance, muddy site; high noise and vibration, high labor intensity.

III. Rotary Drilling

Working Principle: The drill bit (such as a roller cone bit or PDC bit) cuts through the formation across the entire surface by rotating the drill rod. It must rely on circulating media (mud, air, or water) to cool the drill bit, carry cuttings, and stabilize the borehole wall.

Core Features:

Advantages: Maximum drilling depth, the only choice for ultra-deep holes; best wall protection effect, effectively dealing with complex and unstable formations; powerful core sampling capability, suitable for geological exploration; can achieve complex processes such as directional drilling.

Disadvantages: Large and complex equipment with numerous supporting systems; highest overall cost; not efficient in shallow and medium-depth drilling; troublesome mud treatment and significant environmental pressure.

How to Choose the Optimal Method

The choice depends on four core factors: project objective, geological conditions, environmental constraints, cost, and construction period. The decision-making logic is as follows:

1. First, clarify the project objective:

Building pile foundations/engineering piles: Prioritizing drilling quality, efficiency, and environmental protection, rotary drilling is the first choice.

Water wells/geothermal wells: Focusing on well quality and wall protection, use rotary drilling for shallow and medium-depth layers, and swivel drilling for medium and deep layers.

Geological exploration/scientific drilling: The core objective is to obtain rock cores, necessitating the use of swivel drilling (coring).

Mineral/oil and gas drilling: Extremely deep, requiring swivel drilling.

2. The core basis is geological conditions:

Soil layers, sand layers, soft rock: This is the domain of rotary drilling, with unparalleled efficiency.

Hard bedrock, large boulders: Impact drilling is the most economical and effective. For situations requiring extremely high quality and efficiency and with a sufficient budget, consider using a high-power rotary drilling rig with specialized drill bits.

"Soft top, hard bottom" composite strata: This is the most commonly used combination method. Rotary drilling is used to treat the upper soft soil layer, while impact or rotary drilling is used to treat the lower hard rock, offering the best technical and economic efficiency.

For unstable strata such as quicksand and thick silt: Rotary drilling combined with high-quality drilling mud or full casing is a common solution. For deep strata with extremely complex formations, rotary drilling (with mud wall support) is more reliable.

3. Fully consider environmental and site limitations

Urban centers and areas with strict environmental regulations: Rotary drilling (low noise, low vibration, less drilling mud) is almost the only option.

Suburbs and fields: Impact or rotary drilling can be flexibly selected depending on the geological conditions.

Confined space: Impact drilling is relatively flexible, while large rotary and rotary drilling require a larger working face.

4. Ultimately balance cost and schedule

With tight deadlines: In suitable strata, the high efficiency of rotary drilling can offset its high operating costs, resulting in the highest overall benefit.

Limited budget: Percussion drilling is the lowest-cost option.

Extreme depth or special processes: The high cost of rotary drilling must be accepted.

Summary: Rotary drilling represents modern engineering efficiency and quality, suitable for most soft soil to soft rock formations.

Percussion drilling is an economical special forces tool for extremely hard rock formations, sacrificing efficiency and hole quality for powerful rock-breaking capabilities.

Rotary drilling is the ultimate solution for deep holes and complex formations, with core advantages in deep holes, wall protection, and core sampling.

Optimal method decisions begin with a detailed and reliable geological survey report. For complex conditions, a combination of methods is the smartest and most economical choice.