Free Tool
Survey Calculator (Minimum Curvature)
Paste a full directional survey and get TVD, north, east, vertical section, closure, dogleg severity, build, turn and tool face for every station, calculated exactly as GeoMaster does. Nothing leaves your browser.
Paste from a spreadsheet or survey report: spaces, tabs, commas or semicolons. Header lines are skipped.
Tie-in point (optional)
The station at the tie-in MD takes these values and every later station builds from them. MD and TVD are both needed; north and east are optional.
Paste a survey or load the example to see the results.
How it is calculated
Between consecutive stations the wellbore is treated as a circular arc. With inclination I, azimuth A and dogleg angle β:
cos β = cos(I₂ − I₁) − sin I₁ · sin I₂ · (1 − cos(A₂ − A₁)) RF = (2/β) · tan(β/2) (1 when β < 0.0001 rad) ΔTVD = ΔMD/2 · (cos I₁ + cos I₂) · RF ΔN = ΔMD/2 · (sin I₁ cos A₁ + sin I₂ cos A₂) · RF ΔE = ΔMD/2 · (sin I₁ sin A₁ + sin I₂ sin A₂) · RF DLS = β ÷ ΔMD × 30 (°/30 m; ×100/30 for °/100 ft) VS = N · cos(VSA) + E · sin(VSA)
This is GeoMaster's own engine: the calculator is checked against it on reference surveys covering tie-ins, duplicate depths, magnetic and true azimuths, turns through north and near-zero doglegs, and must match to within floating-point precision.
Common questions
It turns survey stations (measured depth, inclination and azimuth) into the wellbore position at each station: true vertical depth, north and east offsets, vertical section, closure, and the dogleg severity, build rate and turn rate between stations. This calculator processes the whole survey at once rather than one pair of stations.
The minimum curvature method, the industry standard, which models the wellbore between stations as a circular arc. The ratio factor (2 ÷ β) × tan(β ÷ 2) corrects the balanced tangential result for that curvature, and is taken as 1 for doglegs under 0.0001 radians.
Yes. The calculator mirrors GeoMaster's own calculation engine line for line and is checked against it on reference surveys, including tie-ins, duplicate depths, magnetic and true azimuths, turns through north and near-zero doglegs. The same survey gives the same numbers here and in the platform.
The direction onto which horizontal displacement is projected to give vertical section: VS = North × cos(azimuth) + East × sin(azimuth). It is normally the planned direction of the well. It defaults to 0° (north), as in the GeoMaster engine, so set it to your plan's section azimuth.
By default, as in the GeoMaster app, positions are measured from the first station, which is taken as TVD 0. For depths from surface, either give a tie-in (the MD, TVD and optionally north and east of a known station) or tick the option to assume the hole is vertical from surface to the first station, which adds a station at MD 0 with zero inclination. The calculator always says which of these it has done.
Positions are computed in grid north. Grid azimuths are used as they are; true azimuths have the grid convergence subtracted; magnetic azimuths have the magnetic declination added and the grid convergence subtracted. Enter the declination and convergence for your well when you choose those references.
Every survey, processed as it lands
GeoMaster runs this calculation on every survey as the well is drilled, and DrillTracker compares each station with the plan: distance to plan, offsets and the steering required.
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