3 Core Sampling Tips to Prevent Breakage & Loss for Geological Core Drill Rigs

In geological exploration core drill rig (LEZ) operations, core breakage or detachment directly leads to data invalidation. The primary cause is the selection of the wrong sampler. Mastering the following three selection techniques based on formation, hole depth, and accuracy can improve the average core recovery rate to over 95%.

I. Tip 1: Match Sampler Structure to Formation Type

Different formations require different sampler designs to protect core integrity.

1. Intact Hard Rock Layers (e.g., granite)

• Problem: The core is hard but easily detaches during drill stringing.
• Recommendation: Diamond single-tube sampler. Diamond cutting is highly efficient, and the single-tube structure provides reliable clamping force.
• Avoid: Using ordinary alloy samplers, which are prone to wear and breakage at the core tip.

2. Soft Rock/Clay Layers (e.g., mudstone)

• Problem: The core is loose and easily dispersed by drilling mud or adheres to the inner wall of the sampler tube.
• Recommendation: Double-tube single-action sampler. The outer tube separates from the drilling mud, and the inner tube does not rotate to protect the soft core's shape. Xinhao products often come with an anti-sticking coating.

3. Fractured Formations (e.g., weathered rock zones)

• Problem: The core is fragmented, and conventional samplers often fail to collect all the fragments.
• Recommendation: Wireline coring + semi-combined tube. Core sampling can be performed without lifting the drill, reducing disturbance; the semi-closed tube allows for easy removal of fragmented rock cores, avoiding secondary damage.

II. Tip Two: Adjust Sampler Specifications According to Drilling Depth

Hole depth directly affects drill rod stability; the sampler length and wall thickness must be adjusted accordingly.

1. Shallow Hole (≤50 meters)

• Recommendation: Lightweight, short model (1-1.5 meters long, 3-4 mm wall thickness). Lightweight to avoid crushing the rock core.
• Scenarios: Construction sites, highway surveys, etc.

2. Deep Hole (≥100 meters)

• Problem: Large drill rod sway, easily causing rock core collision and breakage.
• Recommendation: Thick-walled, long model (2-2.5 meters long, 5-6 mm wall thickness). Xinhao deep hole samplers use thickened tube walls and may have built-in buffer springs to absorb vibration, improving stability and efficiency.

3. Medium-Deep Holes (50-100 meters)

• Recommended: Standard size (approx. 1.8 meters long, 4.5 mm wall thickness). Balances flexibility and stability.

III. Technique 3: Selecting the Sampler Material Based on Exploration Precision