Drillhole Geometry Calculator

DRILLHOLE GEOMETRY

Calculate Hole Geometry

Enter the drilled length and inclination of the hole to calculate its vertical and horizontal displacement.

LENGTH & INCLINATION

Drillhole Geometry

Estimate the vertical and horizontal components of a straight drillhole.

DRILLED LENGTH

INCLINATION

Inclination is measured from horizontal: -90° is vertically downward, 0° is horizontal, and +90° is vertically upward. Valid range: -90° to +90°.

ESTIMATED HOLE GEOMETRY 866.03 ft vertical displacement 500.00 ft horizontal displacement

FORMULA

Drillhole Geometry Formula

A straight drillhole can be resolved into vertical and horizontal components using its drilled length and inclination.

Vertical Displacement

Vertical displacement is calculated from the drilled length and the sine of the inclination angle.

Vertical = Length × |sin(Inclination)|

A 1,000 ft drillhole inclined at -60° has a vertical displacement of approximately 866.03 ft.

Horizontal Displacement

Horizontal displacement is calculated from the drilled length and the cosine of the inclination angle.

Horizontal = Length × |cos(Inclination)|

The same 1,000 ft drillhole inclined at -60° has a horizontal displacement of 500 ft.

Inclination Convention

Geo Corner measures drillhole inclination from horizontal. An inclination of 0° represents a horizontal hole, while -90° represents a vertically downward hole.

0° = horizontal
-90° = vertically downward

Positive inclinations represent holes directed above horizontal. This calculator accepts inclinations from -90° through +90°.

Worked Example

For a 1,000 ft drillhole inclined at -60°:

Vertical ≈ 866.03 ft
Horizontal = 500 ft

Together, these components describe the simplified two-dimensional geometry of the straight drillhole.

INTERPRETATION

Understanding Drillhole Geometry

Drillhole geometry describes how drilled length is distributed between vertical and horizontal displacement. The calculation provides a simplified representation of a straight hole.

Drilled Length

Drilled length is the distance measured along the drillhole. It is not the same as vertical depth unless the hole is drilled vertically.

Vertical Displacement

Vertical displacement is the magnitude of the vertical component of the drillhole. It does not by itself represent the elevation or reduced level of the end of the hole.

Horizontal Displacement

Horizontal displacement is the magnitude of the horizontal component of the drillhole. Without an azimuth, this value does not describe a specific horizontal direction.

Inclination Direction

Positive and negative inclinations distinguish holes directed above or below horizontal. The calculator reports displacement magnitudes, so inclinations of +60° and -60° produce the same vertical and horizontal magnitudes.

LIMITATIONS

Straight-Hole Geometry & Drillhole Surveys

This calculator represents an idealized straight drillhole. Actual drillholes may change orientation with depth and require downhole survey data for accurate three-dimensional positioning.

Hole Deviation

Drillholes can deviate from their planned inclination and direction as drilling progresses. A single collar inclination may therefore not represent the entire hole.

Azimuth

This calculator does not use drillhole azimuth. Horizontal displacement is reported only as a magnitude and cannot be resolved into directional coordinate changes without an azimuth.

Downhole Surveys

Survey measurements collected at intervals along a drillhole can be used to model changes in inclination and azimuth. Surveyed holes require more advanced trajectory calculations than the straight-hole geometry used here.

Geometry vs. True Thickness

Drillhole geometry and geological true thickness are different calculations. True thickness depends on the angle between the drillhole and the geological plane or body being intersected, not simply the inclination of the drillhole.