Applicable Scenarios for Different Drilling Methods (Percussion Drilling and Rotary Drilling)

Applicable Scenarios for Different Drilling Methods (Percussion Drilling and Rotary Drilling)

The drilling methods commonly used for household and small-scale engineering projects mainly include percussion drilling and rotary drilling. They have different working principles and are suitable for vastly different geological conditions. Choosing the correct drilling method is crucial for efficient and economical well construction.

I. Percussion Drilling (commonly known as "hammer drilling")

Working Principle: Mechanical power is used to repeatedly lift a heavy drill bit (impact hammer) to a certain height and then allow it to fall freely, relying on gravity and impact force to break the rock or hard soil layer at the bottom of the well.  Special tools are then used to remove the broken rock fragments.

Main Advantages:

Strong crushing ability and significant effect on hard rock formations and large pebble layers.

Relatively simple equipment structure and easy maintenance.

Usually results in a larger well diameter.

Main Disadvantages:

Extremely inefficient in loose sandy or clayey layers, and prone to wellbore collapse.

Drilling speed is usually slow.

Most Suitable Scenarios:

Mountainous and hilly areas with geological conditions primarily consisting of hard bedrock (such as granite, limestone) and thick layers of large-grained pebbles.

Not suitable for soft strata mainly composed of loose sand and silt.

II. Rotary Drilling

Working Principle: Power drives the drill pipe and drill bit to rotate at high speed, using the cutting or grinding action of the drill bit's edges to break the formation. Simultaneously, water or mud (circulating fluid) is pumped in to carry the drilled cuttings out of the wellhead, and also to protect the wellbore and prevent collapse.

Main Advantages:

High efficiency and fast drilling speed in soft to medium-hard overburden layers (such as clay, sand, and gravel layers).

Mud circulation effectively stabilizes the wellbore in loose formations, resulting in good well quality.

Allows for relatively continuous automated drilling.

Main Disadvantages:

Efficiency decreases significantly when encountering extremely hard, intact bedrock, requiring the replacement of special drill bits (such as alloy drill bits, roller cone bits).

The equipment system is relatively complex and requires maintenance of the mud circulation system.

Most Suitable Scenarios:

Plains, basins, and river valleys where geological conditions are primarily composed of soil, sand, and gravel layers. This is currently the most common drilling method for household and small-scale water wells.

III. How to Choose?

Primary Basis – Local Geological Strata: This is the decisive factor. It is crucial to consult experienced local well drillers or examine the conditions of successful wells in the surrounding area to understand the main geological strata beneath your location.

Simple Assessment:

If drilling in the surrounding area generally requires penetrating thick layers of rock, impact drilling should be prioritized.

If good water can generally be found in soil and sand layers at depths of tens of meters, then rotary drilling is the best choice.

Consider combination models: Many small drilling rigs on the market are "impact-rotary combination" types, which can switch functions to handle complex geological strata (rotary for soft soil, switch to impact for hard rock). This type of machine is more adaptable and a good compromise.

Summary: Choose the right drill for the job, and you'll get twice the results with half the effort.

The core principle of choosing a drilling method is to "use the drill that is best suited to the geological strata."

For hard rock formations, choose impact drilling.

For soft soil formations, choose rotary drilling.

Accurately assessing the geological conditions is the first step in making a wise choice and avoiding wasted time and money.