drilling · directional
Well-to-Well Separation
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Inputs
ft
ft
ft
ft
ft
ft
Description
Computes wellbore-to-wellbore geometric separation — lateral distance, vertical distance, and total 3D distance — between two wells' surveyed N/E/TVD positions at a common comparison depth, plus the compass azimuth of the separation vector. Distinct from Reservoir's well_spacing (a drainage-radius pattern-spacing concept, no survey data involved) and Land & Ownership's spacing_unit_acres (legal pooling-unit acreage, not a distance at all) — this is the directional-survey-based, wellbore-to-wellbore distance calculator referenced by both of those calcs' disambiguation notes.
Variables
| Symbol | Unit | Description |
|---|---|---|
| ΔH | ft | Lateral Separation |
| ΔTVD | ft | Vertical Separation |
| D | ft | Total 3D Distance |
| θ | ° | Separation Azimuth |
| N₁ | ft | Well 1's cumulative northing position (e.g. from minimum curvature survey), referenced to a common field coordinate origin shared with Well 2. |
| E₁ | ft | Well 1's cumulative easting position, referenced to the same coordinate origin as Well 2. |
| TVD₁ | ft | Well 1's true vertical depth at the comparison point, referenced to the same vertical datum as Well 2. |
| N₂ | ft | Well 2's cumulative northing position, referenced to the same coordinate origin as Well 1. |
| E₂ | ft | Well 2's cumulative easting position, referenced to the same coordinate origin as Well 1. |
| TVD₂ | ft | Well 2's true vertical depth at the comparison point, referenced to the same vertical datum as Well 1. |
Assumptions
- Both wells' N/E/TVD positions are referenced to the same coordinate origin, north reference (true, grid, or magnetic), and vertical datum
- Positions being compared are at the same true vertical depth or measured-depth reference point intended for the comparison (e.g. landing depth, casing point, or a common survey MD)
- Survey data feeding both positions is of comparable quality — mixing a high-confidence gyro survey with a raw uncorrected MWD survey understates true positional uncertainty
Limitations
- A straight-line geometric distance only — does not itself account for survey positional uncertainty (error ellipses), which anti-collision software layers on top of this separation
- Comparing positions at a single depth does not confirm minimum separation is maintained along the full length of both wellbores — for multi-well pad development, run this at multiple depths or use dedicated anti-collision scanning software
- Mixing true-north and grid-north referenced coordinates between the two wells will produce an incorrect azimuth
Use Cases
- → Anti-collision separation check: Verify two wellbores maintain adequate 3D separation at a given depth during multi-well pad drilling or planning.
- → Offset well proximity screening: Quantify how close a planned well passes to an existing offset wellbore before finalizing a trajectory.
- → Multi-lateral spacing verification: Confirm as-drilled lateral spacing between adjacent horizontal wells matches the planned development spacing.
Related Calculations
Region Notes
Permian Basin
Densely spaced multi-well pads in the Delaware/Midland Basins routinely target lateral spacing under 10 ft at landing depth — every survey update should be checked against this calc's separation output.
Bakken
Multi-well pad development on the Middle Bakken/Three Forks stack relies on frequent well-to-well separation checks to avoid collision in the tightly stacked landing zones.
Global
Always confirm both wellbores' coordinates share the same north reference and coordinate origin before trusting the azimuth output — a mismatch between true-north and grid-north data is a common source of anti-collision errors.
References
Primary source
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