neqsim-seabed-protection-screening

Seabed Protection Screening: Trenching, Burial and Rock Dump

A flowline or export pipeline is rarely just laid on the seabed. Where trawl gear, anchors, dropped objects, ice keels or upheaval buckling threaten it, the line is trenched, buried, rock-covered or supported, and that decision moves three things the rest of a study depends on: the schedule (trenching rate, not lay rate, often sets the offshore duration), the cost and rock tonnage, and the thermal behaviour of the line - a buried line cools down much more slowly than an exposed one, so hydrate margin and no-touch time change with the burial state.

This skill makes that scope visible early. It samples public or project map layers along the route, assigns a hazard-driven cover requirement per segment, decides whether the soil allows trenching or forces a rock dump, sizes the rock, and hands the resulting burial state to NeqSim thermal and cooldown models. Every default is a recorded placeholder, and every missing input is a reported data gap.

It is a screening tool. It does not perform a trawl interference, upheaval buckling, free-span, on-bottom stability or pipe-soil assessment; those are the downstream standards listed under References.

When to Use

• A tie-back, export line or SURF study needs a first estimate of trenching and rock-dump scope along a route.
• A map layer (seabed substrate, vessel or fishing density, ice scour, protected area, existing pipelines) should decide where protection is needed.
• Crossings of existing pipelines and cables need rock quantities.
• Free-span candidates from survey processing need support quantities.
• A cooldown or hydrate-margin study must reflect which parts of the line are buried, rock-covered or exposed.
• Two routes or burial philosophies (trench everywhere versus rock only at crossings) are compared on trench length, rock tonnes and days.

When Not to Use

• As a trawl-gear interaction, upheaval-buckling, free-span, stability or pipe-soil assessment. It supplies geometry and quantities, not code checks.
• To select a trenching contractor or tool. Capability and rates are placeholders.
• As a geotechnical interpretation. Surface substrate classes are not a strength profile and not a trenchability statement.
• For pre-lay route survey, boulder clearance or shore-approach design.
• On confidential layers in a public workspace. Inputs must be public, synthetic or approved for open-source use; enterprise map access belongs to the enterprise workflow.