Well Trajectory Planner

Design directional well trajectories from surface to target. Plan build-and-hold, S-curve, and horizontal well paths with minimum curvature calculations and dogleg severity analysis.

Drilling Directional Well Planning

Input Parameters

Units

Surface Location

m
m

Target Location

m
m
m

Trajectory Design

m TVD
deg/30m
deg
m

Presets

Results

Theory & References

Minimum Curvature Method

Survey calculation method:

The minimum curvature method assumes the wellbore follows the shortest path (a circular arc) between two survey stations.

Dogleg angle (β):

cos(β) = cos(I₂ - I₁) - sin(I₁) × sin(I₂) × [1 - cos(A₂ - A₁)]

Ratio factor (RF):

RF = 2/β × tan(β/2)

Coordinates:

ΔN = ΔMD/2 × [sin(I₁)×cos(A₁) + sin(I₂)×cos(A₂)] × RF

ΔE = ΔMD/2 × [sin(I₁)×sin(A₁) + sin(I₂)×sin(A₂)] × RF

ΔTVD = ΔMD/2 × [cos(I₁) + cos(I₂)] × RF

Trajectory Types

Build-and-Hold (J-curve):

  • Vertical section from surface to KOP
  • Build section: curve to target inclination
  • Hold section: constant angle to TD
  • Most common directional well design

S-curve:

  • Build section to maximum inclination
  • Hold section at constant angle
  • Drop section back to vertical
  • Used to avoid surface obstacles, return to vertical at target

Horizontal:

  • Build to 90° inclination
  • Hold horizontal through reservoir
  • Maximum reservoir contact

Dogleg Severity (DLS)

Definition: Rate of change of wellbore direction

DLS = β / ΔMD × 30 (or × 100 for imperial)

Where β is the dogleg angle between stations

Typical limits:

  • Rotary drilling: 2-3 deg/30m (6-10 deg/100ft)
  • Motor/steering: 6-10 deg/30m (18-30 deg/100ft)
  • High DLS causes casing wear, torque, drag
  • Build rate = DLS during build section

Build rate considerations:

  • Lower build rate = longer build section
  • Higher build rate = shorter radius, more stress
  • Formation, BHA, casing program limit achievable rates