Drilling Program – Step Out Drilling vs. Infill Drilling

Soil sampling and geophysics are employed by a mining company’s geologist to detect the presence and position of an ore body (i.e., an anomaly). When an anomaly is found, the mining company initiates a drilling program to test the extent of the mineralization. The drilling program is followed by an assessment to determine if the project could potentially be economically developed based on the drill results.

A drilling program often consists of step-out drilling and infill drilling. Step-out drilling programs have a fixed starting point and aim to expand the mineralization zone; larger property sizes are preferable. Infill drilling programs are used to confirm the presence of mineralization between step-out drill holes. Drilling at an angle tests the slant of the mineralization.

After a geologist defines the drill targets based on a thorough analysis of various exploration techniques, a drilling program is initiated to test the potential mineralization within the Earth’s crust. The drill program must confirm the presence of the sought-after mineralization and determine the shape and continuity of the minerals found.

Core samples are taken from every drill target in the program. These samples are then split vertically: half is sent to a lab for mineralization testing, while the other half is stored for future reference.

Understanding the slant of the mineralization is crucial for determining the appropriate drilling angle, as ore bodies are often not solely positioned horizontally beneath the surface. If the mineralization is horizontal, vertical drilling can be conducted. The slant of the mineralization can be described using two parameters: strike and dip. The strike represents the direction in which the deposit extends horizontally, while the dip indicates the angle at which the deposit slopes downward from the horizontal plane. To clarify this concept, refer to the figure below.

Vertical Drilling vs. Angle Drilling

Follow me on X, the platform I exclusively use to announce new content and updates for My Portfolio.