Leading subsea LiDAR systems provider 3D at Depth is pleased to announce the successful completion of a trial that saw the use of an Inertial Navigation System (INS) to aid LiDAR data collection from a moving platform.
The project was jointly sponsored by TechnipFMC, 3D at Depth LLC using its inertial navigation partner iXblue.
Under the Joint Development Agreement (JDA), 3D at Depth and iXblue successfully integrated and collected motion compensated subsea LiDAR data of an oilfield in water depths greater than 2,000m.
The trial took place in December 2016, and validated the capability of INS aided subsea LiDAR for a variety of applications including field mapping and spool metrology and out of straightness.
Based on the results, 3D at Depth and iXblue have now developed a commercial version of the INS aided Subsea Laser (SL) mapping solution, which will be available for field mapping projects at the beginning of April 2017.
A second SL mapping solution is under development for a commercialised spool piece metrology solution that will launch later in the year.
Overall, the system incorporates 3D at Depth’s SL1 subsea LiDAR system, a Phins INS coupled with a 1,200kHz DVL, iXblue RAMSES and a 3D at Depth Subsea FiT (fiber / time Multiplexer) consolidated into a tightly coupled solution.
During the trial, several characterisation scanning passes were performed over a flow line and well centre infrastructure to determine the preferred altitude and speed.
Although these characterisation passes added time to the data collection campaign, they provided important information for understanding the optimal parameters for performing field mapping and metrology the well center and pipeline was surveyed with 25 pipeline transits and 54 well centre transits at differing altitude and speeds.
Within the 10-hour trial, the INS aided SL1 collected more than 200 million points in 79 passes at altitudes ranging from 2m-20m.
The resulting high density point clouds were output into a robust industry standard e57 format that included geo-referenced spatial coordinates and the intensity of each laser pulse.
The intensity value is unique to the SL sensors as this information defines specific features, including pipeline field joints, stencilled lettering on structures and umbilical’s on the seabed.
The initial results demonstrate significant time savings for high-resolution subsea mapping at altitudes from 2m to 20m with variable ROV speeds from ROV Station keeping in heading control mode up to 2k.
Post-processing analysis of the dynamic point cloud data showed a very close correlation with existing static-scanned point cloud data for the same field.
iXblue offshore technical manager Jim Titcomb said: "iXblue is excited for the opportunity to combine 3D at Depths unique time of flight Subsea LiDAR system with the best-in-class navigation provided by our Phins / Ramses subsea positioning system.
"Aiding Phins, utilsing Ramses with two acoustic beacons yielded highly precise results with 3D at Depth reporting 2cm registration delta between the mobile scans and the ground truth data set.
"Comparing a previous metrology utilising a static-based seabed SubSea LiDA, scanning methods with the mobile point cloud resulted in a length measurement that differed from the ground truth by only 1.8mm over a range of 22.45m."
3D at Depth co-founder and director of software engineering Brett Nickerson added: "It’s exciting to leverage my background in airborne and space based LiDAR methodologies to subsea applications.
"Coupled with iXblue’s high-performance inertial navigation technology, the 3D at Depth Systems is the highest resolution and most precise system of its kind for subsea mapping and metrologies."