Typical HDD Projects

HDD Ashore Crossing for CNOOC Yacheng13-1 Submarine Pipeline Gaolan Branch

Time: 2018-09-16 10:02:40 View: 13674

HDD Ashore Crossing for CNOOC Yacheng 13-1 Submarine Pipeline Gaolan Branch

On June 14, 2018, Huayuan completed shore pulling of a submarine pipeline by using HDD Technique for the first time domestically, and innovated a brand-new construction technology for onshore / offshore pulling of submarine oil / gas pipelines.

Gaolan Branch of CNOOC Yacheng 13-1 Submarine Pipeline is the first project whose shore pulling was successfully completed by using Horizontal Directional Drilling (HDD) technique, resolving such difficulties as large difference of elevations, complicated topography along the coast, obstacles of live pipelines in vicinity, and huge waves of the sea; reducing cost and construction time; ensuring the accomplishment of subsequent follow-up works. The Client CNOOC and the EPC Contractor gave a high appraisal to Huayuan for this excellent performance.

Gaolan Branch of CNOOC Yacheng 13-1 Gas Pipeline, is one of CNOOC’s projects for developing the Gas Fields in the South China Sea. After completion of this project, GaolanTerminal will be connected with the Gas network of Hong Kong, eventually forming vast gas transmission networks on the sea which can link up the Eastern gas fields and Western gas fields, and connect Eastern Terminal, GaolanTerminal and Hong Kong Terminal. Gas sources and their transmission then can be flexibly, efficiently deployed in large scale.

The HDD entry site is located within Gaolan Terminal, which belongs to parts of CNOOC’s deep-water gas field in the South China Sea; the exit site is located at the seabed. HDD crossing chainage length is 876m, with 100m of maximum vertical depth, the level difference between the entry point and exit point is 60.6m, the φ610mm×δ22.2mm pipeline is coated with 3LPP anti-corrosion layers.  

Huayuan company was the contractor of the HDD ashore crossing works of the submarine pipeline, whose work scope included surveying, design and construction. Facing the unprecedented working situations and challenges, Huayuan persevered in its own technical innovation, made full use of its superiority of technological advantages, and finally rose to the challenges. According to different strata formation, stages of pilot drilling was carried out; and when enlarging / smoothing the borehole, forward reaming method was used. Lastly with the assistance of pipe lay barge, the pipeline was successfully pulled back into the borehole. During the construction of this HDD project, Huayuan Company innovated brand new working methods or techniques to conquer such difficulties as: high abrasiveness and hardness of  granite / quartz vein which might have worn the drill bits severely; formation of cutting beds due to drilling fluid Lost Circulation when forward reaming; and eccentricity of the borehole formed at the interface of hard and soft layers.