Huayuan News
At 18:00 on April 26, 2020, the back-haul of the submarine pipeline directed drilling crossing project for the Shandong landing of the connection pipeline project of the Xin'ao Zhoushan LNG Receiving and Bunkering Station in Zhejiang Province, which was undertaken by Hebei Huayuan Science and Industry Co., Ltd., was successfully completed. This created a new record for Huayuan Company in land-sea directed drilling crossing. The project involved a weighted lining pipeline with a diameter of 1016 mm and a maximum back-haul length of 1542 meters.
As an important supporting project, the Zhoushan LNG Receiving and Bunkering Station in Zhejiang Province is one of the 11 key interconnection projects in the country. The Zhoushan LNG Outbound Pipeline Project is of great significance in opening up the future land-sea LNG corridor. The entire project is over 80 kilometers long and consists of 9 sections, including 5 sections of onshore pipelines (land area) and 4 sections of submarine pipelines (sea area). The project construction environment is complex, and the onshore geological and geomorphic conditions are harsh. It encompasses many difficulties that may be encountered during the construction of long-distance pipelines at present. It is one of the most challenging projects in the domestic sea area and even in the international pipeline construction industry. In terms of the site conditions, geological conditions, and project scale, the directed drilling crossing project for the Shandong landing of the submarine pipeline is the most difficult and controlling project of the entire project.
Meanwhile, the land-sea directed drilling crossing project for the Xiushan West, which was also undertaken by Huayuan Company, was successfully back-hauled from land to sea in January 2020.
The back-haul length of the pipeline in this project is 1542 meters. The diameter of the steel pipe is 1016 mm, and the wall thickness is 25.4 mm. There is a 40-mm-thick concrete weight layer outside the steel pipe, and the outer diameter of the back-haul pipeline is 1100 mm. The elevation difference between the entry and exit points is 22 meters, and the crossing depth is 49 meters. It is one of the land-sea directed drilling crossing projects of Huayuan Company with the largest pipe diameter, the longest length, the most diverse geological conditions, and the most complex site conditions. The successful completion of the project has witnessed Huayuan Company's ability to carry out horizontal directional drilling crossing construction under complex conditions. It has also accumulated new experience for the horizontal directional drilling crossing project of submarine pipeline landing, providing new impetus for the development of the industry.
The entry point of this project is located on a steep mountain slope, making it extremely difficult for equipment to enter the site. Huayuan Company invested in the modular HY-6000ZH (with a maximum back-haul force of 600 tons) super-large drilling rig independently designed and manufactured. The rig was disassembled for transportation and assembled on-site, solving the problem of large-scale equipment being unable to reach the island in the early stage of the project. The geological conditions of this project's crossing are complex, ranging from the relatively strong slightly weathered tuff to the softest submarine silt layer, and passing through various strata such as silty sand and silt in between. For this highly challenging project, Huayuan Company invested in the self-designed and developed offshore construction drilling rig vessel (Tianze No.1), and formulated a series of plans and measures, including using 8-5/8" large-diameter drill pipes for segmented drilling, assisting in positioning the offshore drill bit, segmented forward reaming, synchronous reaming with two drilling rigs, hole measurement, hole repair, offshore assisted back-haul (emergency plan), overall prefabrication and underwater laying of the pipeline, and pipe pile positioning, to ensure the smooth completion of the project.
During the project construction period, in the face of the sudden COVID-19 pandemic, while implementing the government's prevention and control measures, the project management team carried out closed management of construction workers according to the characteristics of the project, postponed personnel rotation, minimized the impact of the pandemic on construction, and ensured the simultaneous progress of pandemic prevention and control and project construction.
In recent years, the construction method of land-sea directed drilling crossing has been increasingly widely used in the construction of the ocean landing sections of pipelines of various specifications and with different transportation media. This is mainly due to its advantages in many aspects, such as environmental protection, the safety of pipeline operation in the later stage, and no impact on shipping routes and terminals. The successful implementation of this project has accumulated new experience for the horizontal directional drilling crossing project of submarine pipeline landing, formed a relatively mature construction technology for land-sea crossing of large-diameter and long-distance pipelines, and will play a guiding and reference role for more complex similar projects in the future.
