| name | neqsim-pipe-route-profile |
| calculation_basis | screening |
| version | 0.1.0 |
| description | Educational pipe-route length and elevation-profile screening from supplied waypoints. USE WHEN: a task needs a public, screening-level flowline or riser route length, segment list, and seabed elevation profile from a subsea map before detailed pressure-drop and flow assurance design. |
| last_verified | 2026-05-31 |
| requires | {"python_packages":[],"java_packages":[],"env":[],"network":[]} |
Pipe Route Profile
Use this skill for a quick, public route geometry screening of a subsea flowline or riser. Given an ordered list of waypoints with seabed depths, it builds segment lengths, a cumulative kilometre-point (KP) profile, total route length, and an elevation profile (rise, descent, net change, maximum slope). It is intentionally simple and should guide users toward validated NeqSim hydraulic and flow assurance workflows.
When to Use
- When a user supplies an ordered route (waypoints with seabed depths) and wants the total length and elevation profile.
- When an engineer needs a segment list and KP profile to feed pressure-drop or hydrate screening.
- When an agent should explain that validated NeqSim hydraulic methods are required for design-grade work.
Inputs
waypoints: an ordered list, each with name, x, y, and depth_m (seabed water depth, positive downwards).coordinate_system: cartesian (x, y in metres) or geographic (x = longitude, y = latitude in degrees).max_slope_deg: configurable public seabed-slope guideline (constructor, default 15 degrees).
Sourcing Waypoints and Depths From Open Data
The skill takes waypoints and depths as given. When a route has to be built for a
real field with no survey in hand, both can come from public sources:
- End points. For the Norwegian Continental Shelf the Norwegian Offshore
Directorate FactPages publish CSV exports of every exploration wellbore
(
wellbore_exploration_all: wlbNsDecDeg, wlbEwDecDeg, wlbWaterDepth) and
every fixed facility (facility_fixed: degree/minute/second columns plus
fclWaterDepth). Export URL pattern:
https://factpages.sodir.no/public?/Factpages/external/tableview/<table>&rs:Command=Render&rs:Format=CSV&Top100=false.
GOTCHA: the wellbore table has decimal-degree columns but the facility table
only has DMS, so convert. Both are ED50, which differs from WGS84 by of order
100 m on the NCS -- negligible for screening lengths, not for a survey route.
- Seabed depth. The EMODnet Bathymetry DTM has a public point REST API,
https://rest.emodnet-bathymetry.eu/depth_sample?geom=POINT(<lon> <lat>),
which returns avg/min/max elevation in metres, negative downwards;
negate it to get the depth this skill expects. Cache responses to disk -- a
500 m-spaced profile over a 70 km route is around 150 calls.
- Intermediate waypoints. With only two end points, interpolate along the
great circle (spherical slerp) at a fixed spacing and sample the DTM at each
point. That yields a straight-corridor screening profile; it is not a routed
corridor and carries no obstacle avoidance.
- Sanity check. Compare the DTM depth at each end point against the water
depth reported for the well or facility. Agreement to a few metres is the
cheapest available validation that the coordinates and the datum are right.
Outputs
segments: per-segment horizontal length, 3D length, depth change, and slope.total_horizontal_length_km: planar route length.total_route_length_km: 3D (as-laid) route length including depth change.kp_profile: cumulative horizontal KP and seabed depth at each waypoint.net_elevation_change_m: start depth minus end depth (positive means the route ends shallower).total_rise_m and total_descent_m: summed upward and downward seabed change.max_slope_deg: steepest segment slope.slope_warning: ok, watch, or high against the public slope guideline.neqsim_available: whether the optional NeqSim package is importable.assumptions: public assumptions and required follow-up.
Engineering Method
For each consecutive waypoint pair, the horizontal length is the planar Euclidean distance (cartesian) or the great-circle haversine distance (geographic). The depth change is the difference in seabed depth, the 3D segment length is sqrt(horizontal^2 + depth_change^2), and the slope is atan2(|depth_change|, horizontal) in degrees (a vertical step gives 90 degrees). Cumulative KP is the running sum of horizontal lengths. Rise is summed where the route gets shallower and descent where it gets deeper.
The slope warning compares the steepest segment slope to the configurable max_slope_deg guideline: at or above the guideline is high, above 80 % is watch, otherwise ok. This flags candidate free-span or steep-slope sections for follow-up, but is not a span or on-bottom-stability analysis.
This is not a hydraulic model. Pressure drop, temperature loss, hydrate margin, and flow regime along the route must come from validated NeqSim workflows.
Python Usage Pattern
from pipe_route_profile import PipeRouteModel
model = PipeRouteModel(max_slope_deg=15.0)
result = model.evaluate(
waypoints=[
{"name": "Tree", "x": 0.0, "y": 0.0, "depth_m": 340.0},
{"name": "KP2", "x": 2000.0, "y": 200.0, "depth_m": 300.0},
{"name": "Riser base", "x": 8000.0, "y": 1500.0, "depth_m": 120.0},
],
coordinate_system="cartesian",
)
print(result.total_route_length_km)
print(result.net_elevation_change_m)
print(result.slope_warning)
print(result.assumptions)
If the optional neqsim Python package is available, the result records that fact so an agent can recommend moving to validated NeqSim hydraulic and flow assurance workflows. If not, the example still runs with the public geometry logic.
Validation Checklist
Common Mistakes
| Symptom | Cause | Fix |
|---|
| Route is much shorter than expected | Too few waypoints over a curved corridor | Add intermediate waypoints to capture the route shape |
| Slope flags everywhere | Sparse waypoints with large depth jumps | Add intermediate soundings or use bathymetry-profile-screening |
| Elevation sign confusion | Depth is positive downwards | Net positive change means the route ends shallower |
Limitations
- No route optimisation, corridor following, or obstacle avoidance is performed.
- No span, on-bottom stability, or pipeline mechanical analysis is included.
- No hydraulic, thermal, or flow assurance evaluation is performed.
- Results are screening indicators only and are not design route lengths or profiles.
Related NeqSim Functionality
This skill only prepares route geometry. The validated calculations it feeds into live in NeqSim:
neqsim.process.equipment.pipeline.PipeBeggsAndBrills — multiphase pressure and temperature along the route length and elevation profile.neqsim.process.equipment.pipeline.AdiabaticTwoPhasePipe — two-phase hydraulics for a routed segment.- The NeqSim MCP
runPipeline and runFlowAssurance tools for arrival-condition, hydrate, and flow-regime screening along the profile.
In Python these classes are reachable through the neqsim package (for example from neqsim import jneqsim). The total length and elevation profile from this skill are inputs to those hydraulic workflows.
References
