The Haiyang Shiyou 720 deep-water geophysical survey vessel, equipped with China's independently developed marine seismic exploration and acquisition Haijing system, successfully carried out ultra-deepwater seismic exploration operations for the first time and released China's first deep-water three-dimensional stratigraphic structural map, marking a significant breakthrough in key core technologies for deep-sea oil and gas exploration, China National Offshore Oil Corporation (CNOOC) announced on Oct 3.
Submarine cable-enabled seismic exploration technology is the most direct, cost-effective and efficient method worldwide for detection of seabed geological structures. The set of underwater cable-based seismic exploration acquisition equipment is deployed on the sea surface and conducts a "CT" scan of the seabed layers by seismic wave signals to identify oil and gas reservoirs beneath the seafloor.
The Haijing system is the first set of cable-based seismic exploration and acquisition equipment developed and manufactured by China. It consists of multiple equipment systems, enabling submarine cable-powered acquisition, integrated navigation, and positioning and control.
The system breaks through the previous depth limitation of 22 meters for imported equipment, and achieves a full range of coverage from small cable spacing to regular cable spacing. It also has the capability to collect ultra-low-frequency signals at 2 Hz, significantly enhancing seismic data resolution.
According to Chinese offshore oil technical experts, compared to imported equipment the seismic data collected by Haijing has a higher identification degree, and can accurately depict the complex geological structure of a 10,000-meter-level stratum through a water depth of 3,000 meters.
During this mission, the Haiyang Shiyou 720 vessel deployed ten submarine cables of the Haijing system into the sea to carry out the data collection work along the designated route.
Each cable is more than eight kilometers long, forming a data collection network equivalent in size to 1,021 standard football fields. The vessel conducted real-time seismic data collection for source points and receiver points along its course, and accurately delineated oil and gas reservoir locations on the vast sea surface, akin to drawing longitude and latitude lines, thereby enabling high-quality exploration and development of deep-sea oil and gas resources.
Among China's proven oil and gas reserves, about 40 percent are located in deep water areas. This seismic exploration operation took place in the Pearl River Mouth Basin's 3,000-meter ultra-deepwater block, marking China's first three-dimensional seismic exploration in ultra-deepwater areas exceeding 3,000 meters.
Since it was put into use in September 2022, Haijing has completed multiple conventional seismic data collections as well as high-density continuous collections and even high-coverage rolling collections. It successfully completed three-dimensional seismic exploration covering a total of 3,935 square kilometers in four blocks. It has achieved product standardization and industrial production, featuring entire industry chain capabilities from research and development to manufacturing and services and established a complete industrial manufacturing system.
The successful application of Haijing has filled a gap in China's marine cable-enabled seismic exploration technology and positioned China as the third country globally to possess a complete set of marine seismic exploration and acquisition equipment.
(Executive editor: Xie Yunxiao)
