In accordance with the integrity management requirements of CNOOC Shenzhen Branch and CNOOC Deep Ocean Development Co., Ltd., each of the submarine pipelines needs to be inspected regularly.
However, among them, the 30-1 natural gas pipeline is located in extremely shallow waters. According to the requirements of safety regulations, manned boats are not allowed to operate in that area, so the 30-1 pipeline has never been inspected so far.
This pipeline was buried shallowly in the water, while some sections became bare or even suspended due to seawater erosion. The suspended parts may be broken due to uneven force.
In the summer of 2019, the client commissioned OceanAlpha to survey this pipeline. OceanAlpha used the M40 USV to carry a multi-beam echo sounder to scan the water bottom. A total of 7 exposed sections were found during the survey, with the longest continuous exposed section as long as 689 meters and the total exposed length exceeds 1200 meters.
M40 working on the sea
Survey route of the USV
Multibeam data of one exposed section
The survey results showed that the exposure condition of the pipeline will have a serious impact on future operations, providing an accurate reference for the company to carry out further maintenance as quick as possible.