drilling · directional
Closure Distance & Direction
Closure = √(ΔN² + ΔE²); Direction = atan2(ΔE, ΔN)
click formula to derive ↑
Inputs
ft
ft
Description
Computes the straight-line horizontal distance and compass direction from the surface location to the current wellbore position, given cumulative Northing and Easting offsets. Answers the basic "how far and which way" directional question used for target-hit and anti-collision checks.
Variables
| Symbol | Unit | Description |
|---|---|---|
| C | ft | Closure Distance |
| θc | ° | Closure Direction |
| ΔN | ft | Cumulative north-south displacement from the surface location (positive = north). Typically the running total of ΔN from minimum curvature survey calculations. |
| ΔE | ft | Cumulative east-west displacement from the surface location (positive = east). |
Assumptions
- ΔN and ΔE are cumulative values referenced to the same surface location and the same north reference (true, grid, or magnetic — must be consistent)
- No correction for earth curvature is needed at typical single-well horizontal displacement scales
Limitations
- Closure distance alone does not indicate TVD or wellbore inclination — it is a horizontal-plane quantity only
- Mixing true-north and grid-north referenced ΔN/ΔE values from different survey tools will produce an incorrect direction
Use Cases
- → Target-hit verification: Compare closure distance and direction at target depth against the planned target coordinates to confirm the well landed as planned.
- → Surface location planning: Determine how far a subsurface target is from candidate surface pad locations during well planning.
- → Quick anti-collision screening: Get a fast horizontal-separation estimate between wells on a multi-well pad before running a full 3D anti-collision scan.
Related Calculations
Region Notes
Permian Basin
Closure distances of 1,500-3,000 m are typical for Wolfcamp/Bone Spring laterals run from centralized multi-well pads.
Eagle Ford
Pad-based development typically targets closures matched to lease-line setback rules, commonly requiring 460-800 m (1,500-2,600 ft) of lateral closure from the pad.
Global
Always confirm whether ΔN/ΔE — and therefore closure direction — are referenced to true north or grid north before comparing across wells surveyed with different tools.
References
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