China-developed deep trenching technology breaks world records

A multi-functional modular seabed trencher developed by a Chinese firm has recently completed 100 kilometers of pipelines construction in Bangladesh's first marine pipeline project, setting two world records in directional drilling and deep trenching.

The seabed trencher was self-developed by state-owned China Petroleum Pipeline Engineering Co (CPP), which is a professional company specializing in constructing oil and gas storage and transportation infrastructure, under the China National Petroleum Corporation.

The installation of the marine pipeline project in Bangladesh, one of the key projects under the Belt and Road Initiative, needs to complete six directional drillings and reach a buried depth of 11 meters to avoid the commercial and naval waterways, making the unprecedented difficulty in the history of world marine engineering, CPP said.

According to reports, the normal depth of trench digging in the offshore industry is 1.5 meters to 3 meters under the seabed, and reaching 5 meters is already a difficult project for the industry.

To deal with technical difficulties, CPP has carried out independent innovations and upgraded trenching machines to achieve a maximum digging depth of 11.9 meters, mastered the underwater millimeter-level docking technology of offshore single-point mooring and adopted the original technique that ensured a 100 percent success in one-time drilling.

After the project is put into operation, oil tankers above 100,000 DWT that cannot dock to unload oil at ports in Bangladesh, CPP said.

As an important oil and gas storage and transportation project in Bangladesh under the Belt and Road Initiative, the project was launched as Bangladesh is not capable of handling large vessels carrying imported crude and finished oil due to low navigability of a key river channel and constrained facilities at the main seaport in Chittagong, the Xinhua News Agency reported.

In December 2016, Bangladesh reached an agreement with CPP for engineering, procurement, construction and commissioning for the installation of single point mooring with 220-kilometer-long double pipelines, including building a 146-kilometer-long offshore pipeline and 74-kilometer-long onshore pipeline to carry imported oil from sea to a refinery in Chittagong district.

The project is expected to have an annual unloading capacity of 9 million tons.