Dogleg Severity Calculator

Dogleg severity (DLS) is the rate at which a wellbore changes direction, combining changes in both inclination and azimuth into a single angle and normalising it over a standard interval — 30 metres or 100 feet. It is reported in degrees per 30 m or degrees per 100 ft. A higher number means the well is turning more sharply over that interval.

This calculator uses the minimum curvature method, the industry standard. The dogleg angle between two surveys is cos β = cos(I₂ − I₁) − sin(I₁) · sin(I₂) · (1 − cos(A₂ − A₁)), where I is inclination and A is azimuth. Dogleg severity is then β multiplied by the course length and divided by the change in measured depth between the two surveys.

The dogleg angle is the total angular change between two survey stations, in degrees. Dogleg severity normalises that angle over a standard interval, so a 3° change over 30 m and a 3° change over 100 m describe very different wells but would share the same dogleg angle. Always compare severity, not raw angle.

It depends on the well. Limits are set by the bottom hole assembly, casing wear, completion equipment and the rotating hours expected through the interval, so a figure that is routine on one well can be unacceptable on another. Many directional plans work to a planning limit in the region of 3°/30 m for sections that will be rotated heavily, with higher rates tolerated over short build or correction intervals. Use your own well programme rather than a general rule.

Minimum curvature. It assumes the wellbore follows a circular arc between the two survey stations, which is the method used for survey calculation across the industry and the one GeoMaster applies internally. Radius of curvature and average angle methods give slightly different answers, particularly across large survey intervals.