Dredging and Offshore Technology Review

Comprehensive vocabulary flashcards covering dredging industry standards, soil mechanics, offshore oil and gas operations, and safety protocols based on the lecture transcript.

Dredging

The process of removing, transporting, and disposing of soil material from underwater (whereas "earth moving" refers to the same process above water).

Maintenance Dredging

The removal of recently deposited sediment to keep existing waterways at their required depth, such as in the Schelde or the Belgian coast.

Capital Dredging

The removal of soil from an area that has never been dredged before, often involving greater layer thicknesses and more difficult ground conditions, such as the deepening of the Suez Canal.

Land Reclamation

The creation of new land by depositing sediment, exemplified by projects like Singapore Tuas or Doha New Port.

Trailing Suction Hopper Dredger (TSHD)

A free-sailing vessel that drags a suction pipe over the seabed, stores sediment in a hopper, and follows a cycle of trailing, sailing full, discharging, and sailing empty.

Cutter Suction Dredger (CSD)

A stationary vessel that uses a rotating cutterhead to mechanically loosen soil before sucking it up as slurry for hydraulic transport via pipelines.

Backhoe Dredger (BHD)

A stationary dredger equipped with a crane arm and bucket, similar to an excavator, used for high precision in hard soil.

Water Injection Dredger

A hydrodynamic dredging method that fluidizes sediment so that natural currents can carry it away.

GHG Intensity

$\text{CO}_2 \text{ equivalent} / \text{useful work}$; a metric used to measure progress toward becoming climate neutral by 2050.

Rainbowing

A hydraulic disposal method where a dredger sprays a mixture of sediment and water through the air onto a reclamation area or beach.

Backfilling

The process of refilling a previously excavated trench or hole, often to provide structural support for pipelines or foundations.

Granular Soils

Coarse-grained soils like gravel and sand that have little cohesion, no plasticity, and high water permeability.

Cohesive Soils

Fine-grained soils like clay and silt that exhibit plasticity and have low water permeability.

Atterberg Limits

Transition points for cohesive soils, including the Liquid Limit (LL) and Plastic Limit (PL), which define the boundary between liquid, plastic, and semi-solid states.

Consolidation

The time-dependent process where water escapes from soil pores under pressure, leading to a reduction in volume and ground settlement.

CPT (Cone Penetration Test)

An in-situ geotechnical test used to characterize soil layers by measuring the resistance of a cone as it is pushed into the ground.

Geophysical Investigation

Indirect methods such as seismic reflection and seismic refraction used to determine layer thickness and rock dredgeability between boreholes.

Settlement

The rearrangement of soil grains under a load, resulting in a decrease in volume and a sinking of the ground.

PVD (Prefabricated Vertical Drains)

Slender hoses inserted deep into soft soil to shorten the drainage path and accelerate the consolidation process.

Spud Carrier

A longitudinal sliding mechanism on a CSD that supports the main spud and allows the vessel to step forward in increments of $0.5 - 2\,m$.

Cavitation

The formation and subsequent implosion of vapor bubbles in a pump when inlet pressure is too low, causing pitting on the impeller and high wear and tear.

Critical Velocity

The minimum flow velocity required in a pipeline to keep sediment in suspension and prevent blockages.

MODU

Mobile Offshore Drilling Unit; a portable unit used for drilling subsea wells, including jack-ups, semi-submersibles, and drillships.

Dynamic Positioning (DP)

An automated system that maintains a vessel's position and heading using thrusters and sensors instead of anchors.

FPSO

Floating Production Storage and Offloading unit; a floating vessel used by the offshore oil and gas industry to process and store hydrocarbons before transferring them to tankers.

Blowout Preventer (BOP)

A critical safety assembly installed at the wellhead to control pressure and seal the well in case of an unexpected influx of oil or gas (a kick).

X-mas Tree

An assembly of valves, spools, and fittings installed on top of a completed well to control the flow of produced oil or gas.

ALARP

As Low As Reasonably Practicable; a risk management principle aimed at reducing risks to a level where the cost of further reduction is disproportionate to the benefit.

Management of Change (MoC)

A structured process to assess and approve changes in equipment, procedures, or personnel to ensure safety is maintained.

LOTO (Lock Out Tag Out)

A 6-step safety procedure (Preparation, Shutdown, Isolation, Lockout/Tagout, Stored Energy Check, Verification) to ensure machines are de-energized during maintenance.

TRIR

Total Recordable Incident Rate, calculated as $(\text{Aantal recordable cases} \times 200,000) / \text{Totaal aantal gewerkte uren}$; a lagging indicator of safety frequency.

Leading Indicators

Proactive safety metrics that measure activities intended to prevent incidents, such as Near Miss Reporting Rates and Training Completion Rates.

DEVEX

Development Expenditures; the budget allocated to developing an offshore project before construction begins.

CAPEX

Capital Expenditures; the costs associated with building the physical assets of a project, such as wind turbines or platforms.

OPEX

Operational Expenditures; the ongoing costs required to keep an operation running after assets are built.

Capacity Factor (AEP)

Annual Energy Production; a measure of how much electricity an installation produces annually compared to its theoretical maximum.

Floating LiDAR

An autonomous buoy equipped with lasers used to measure wind speed, direction, and metocean conditions at sea.

Fall Pipe ROV (FPROV)

A Remotely Operated Vehicle attached to the end of a fall pipe to provide visual support and ensure precise subsea rock installation.

Princess Elisabeth Island

The world's first artificial energy island, located $45\,km$ off the Belgian coast, combining offshore wind, civil engineering, and dredging.

5 Whys Method

An investigative technique used to determine the root cause of an incident by repeatedly asking why an event occurred.