Lasers & Sources

DeepOcean completes high-resolution 3D subsea laser survey off the coast of Ghana

Feb. 10, 2017

The pipe-survey operation was the first extensive commercial deep-water survey of its kind.

Images acquired by ULS-500 underwater laser scanners include, in color, a pipe survey (left) and, in monochrome, a ship's propeller and shaft to its right lying on the seafloor (right).

ADUS DeepOcean and DeepOcean Ghana Ltd., both subsidiaries of DeepOcean Group Holding BV (DeepOcean; Amsterdam, Netherlands), have recently completed a state-of-the-art deep-water subsea 3D laser survey off Ghana for Tullow Oil (London, England), the first extensive commercial survey of its kind.

The recent climate in the oil and gas industry has increased the need for cost-effective and inventive approaches to many operations offshore, including many "routine" survey and inspection-related tasks.

The survey operations covered 12 drill-center locations and a total of 27 metrologies in water depths between 800 and 1800 m -- a successful demonstration of this rapid noncontact alternative to conventional metrology surveys.

Near-1-cm accuracy
The laser survey was done from a moving remotely operated vehicle. The equipment included DeepOcean's deep-rated 2G Robotics ULS 500 Pro Laser and a SPRINT acoustically aided inertial-navigation system for subsea vehicles from Sonardyne (Yately, England). The accuracy of the survey approached 1 cm in dynamic operation.

The ULS-500 underwater laser scanner is a long-range measurement system that takes measurements across areas from 1.15 m to 10 m in size, capturing 1400 points per line scan. It can sample up to 40,600 points/s (29 profiles/s) and has a range resolution (by itself) of 0.021, 0.382, and 1.220 mm at distances of 1.15, 5.5, and 10 m respectively.

The resulting 3D point clouds, coupled with in-house modeling techniques, provide DeepOcean engineers with the information needed to undertake metrology and to better inform inspection, maintenance, and repair tasks for DeepOcean's clients.

The success of the survey operations has led to a further three-year contract for DeepOcean Ghana Ltd.

Sources:

https://deepoceangroup.com/deepocean-completes-ground-breaking-3d-laser-survey/

http://www.2grobotics.com/products/underwater-laser-scanner-uls-500/

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.