Directional surveys for wells are typically received with data points represented as angles (inclination, azimuth) and depths. This data needs to be converted to Cartesian coordinates for mapping or 3D visualization. This presentation demonstrates the use of FME to replicate the formula from the "Minimum-Curvature Method" to convert well surveys for mapping purposes.

1. Well Directional Survey
Processing in FME
Jerrod Stutzman
Devon Energy

2. Directional Survey for a Well
In geoscience, a directional survey is a
collection of data points recorded along a
wellbore.
Magnetic and/or gyroscopic instruments
are sent down the wellbore to record the
3D wellbore location with high precision.
These instruments record measured
depth, inclination, and azimuth values.

3. Spherical Coordinate System?
Measured Depth (MD), Azimuth
(Az), and Inclination (I) specify
a 3D point in space.
This is essentially a spherical
coordinate system where:
MD = r
Az = φ (clockwise from North)
I = θ (+z is defined as downward)

4. Problem: Raw Surveys “Unmappable”
Azimuth, Inclination, and Measured Depth are all measured with
reference to an origin – that being the surface location of the well.
Obviously, this can’t be used for storing multiple wells in a
geodatabase because they need to have a common origin, coordinate
reference system, etc.!
Therefore, we must convert the survey stations to XYZ coordinates.
The most accurate method for calculating northing and easting offsets
is known as the minimum curvature method.

5. Considerations
- Azimuth angle can be recorded in terms of True, Grid, or Magnetic
North. Must correct for convergence! There are equations for
this, but there is also a Custom FME Transformer.
- Surface Hole location must be known for well to convert ΔN/ΔE to
ΔLon/ΔLat
- Geoscience database stores both sets of coordinates:
- ΔN/ΔE and ΔLon/ΔLat
- ΔN/ΔE needs directional indicators (N,S,E,W)
- ΔLon/ΔLat requires +/- to indicate direction

6. http://os.is/gogn/unu-gtp-report/UNU-GTP-2013-27.pdf
Minimum Curvature Method
This math is all replicated in FME!

7. Workbench Overview
Screenshots of FME workbench math
Minimum Curvature
Calculations happen here

8. Retrieve Well Header & Survey Data
Use Surface Latitude to
calculate feet per degree
conversion factor.
Test Azimuth North
reference

9. Convergence Correction
If azimuth is referenced
to grid north, apply
convergence correction.
Must know grid north
coordinate system!

10. “Multiple Feature Attribute
Support” is the magic behind
this process. Without it, this
would not be possible.
This allows us to use attribute
values from previous (or
subsequent) features!
Workbench: Minimum Curvature Calculations

11. Math Translation to FME - Example
No, it’s not pretty, but it is effective!!
feature[-1].Inc refers to the Inclination value from the previous feature
feature[-1].Azi is the Azimuth value from the previous feature
becomes (via ExpressionEvaluator):

12. Store Processed Surveys
Well Surveys that have been processed using this method
are then written back to the geoscience database with XY
offsets and lat/lon offsets for each station.
These processed surveys can then be used to map all
directional surveys in the database, in 2 and 3-
dimensions! (TVD is used as absolute z value for 3D)

13. Data points are converted from azimuth, inclination, and depth values to
X/Y Offsets and Lat/Lon Offsets. These can be used to map data in
standard coordinate systems (and even in 3 dimensions!)
Summary

14. Directional Survey Points Mapped in 2D and 3D
3D view2D (top-down)
view

15. Thank you!
Jerrod Stutzman
Devon Energy Corp
Jerrod.Stutzman@dvn.com
405-228-8279