Engineering measurements from subsea laser scanning Data gathering and analysis Presented by Brett Lestrange, Regional Director Europe
Introduction There is a growing number of aging subsea assets in use today Repairs and modifications are required to prolong lifespan Engineering data for assets may be limited, or not available Ability to produce accurate as is engineering models is hugely beneficial Historically photogrammetry, sonar and physical measurements have been employed subsea to collect engineering data
Laser scanning applications Modelling of subsea components Spool Metrology Pipeline damage inspection Inspection of wear on subsea components Structural corrosion monitoring
Subsea lasers An increasing number of laser systems are available for subsea use The two most common types of subsea laser scanners Triangulation Time of Flight (TOF) All subsea lasers face similar challenges Mobilisation Subsea Data collection Data processing Report generation Laser scanning creates an almost instant 3D point cloud representation of an objects surface features
Benefits of subsea laser scanning Non contact measurement Scanned area data available in seconds Diver or ROV deployed Ultra High Resolution data Sub millimetre measurement capability Data can be converted to CAD models for measurement and analysis Image of surface corrosion Meshed scanned data
Subsea laser scanning constraints Good visibility is essential Poor visibility will result in increased noise within the data High reflectivity within the scan creates noise within the data Maximum range for triangulation laser systems is typically 10m Ambient light causes reduced laser line detection Overall accuracy of the data decreases with range
Example laser scanning project Wellhead laser inspection Well-bay laser inspection Diver deployment 110m water depth Less than 24hr inspection time Sub millimetre data analysis
Project planning and deliverable requirements Clearly defined measurement requirements A Scan Plan is essential to ensure coverage Agreed reporting format Project specific system integration
Typical diver deployment configuration Subsea equipment including laser scanner, pan & tilt multiplexer Surface equipment including control software and multiplexer console Control laptop Multiplexer topside Subsea laser scanner 150m power and fibre communications umbilical Multiplexer subsea bottle
Final Acceptance Test (FAT) Subsea deployment mock up Computer suite
Data processing (noise) Noisy data requires filtering Noise from turbidity Noise from reflections Initial noise is filtered through software Final filtering performed manually Differing processing requirements from topside laser scanning
Processed data (noise) Before noise filtering After noise filtering
Data processing (scan registration) Multiple scans stitched together Co-locating features between scans (REGISTRATION) Registration targets may be employed Initial manual feature selection Software automatically aligns selected features
Processed data set Registration targets removed during processing CAD models can be created from the processed data Meshed data set CAD model
Example measurements Unrolled heat map Comparison between the scanned data and the CAD model Measurements in millimetres Deformation analysis
Example measurements Horizontal deformation Vertical deformation Ovality analysis Horizontal section Vertical section
Summary An emerging subsea technology Specialised personnel are required to deliver results Subsea laser scanning requires a different skillset to that for topside scanning Deliverables must be clearly defined from the outset Detailed project preparation and FAT minimise offshore risks Scan data can provide critical sub millimetre measurements of subsea infrastructure
Engineering measurements from subsea laser scanning Data gathering and analysis Questions