Bohai Sea Trillion-Cubic-Meter Gas Field Phase II Completed

China has reached a major milestone in offshore energy development as the main structure of Phase II for the Bozhong 19-6 gas field — the first trillion-cubic-meter natural gas field discovered in the Bohai Sea — was completed on June 2, 2026. The achievement marks a significant acceleration in the development of China’s eastern region’s largest integrated gas field, directly bolstering the country’s domestic natural gas production capacity and national energy security.

Context and Background

Discovered by the China National Offshore Oil Corporation (CNOOC) in 2019, the Bozhong 19-6 gas field is located in the central Bohai Sea. According to Xinhua News, the field holds proven natural gas geological reserves exceeding 200 billion cubic meters and oil geological reserves exceeding 200 million cubic meters. It is classified as a condensate gas field with ultra-high condensate oil content, making it technically distinct from conventional gas fields.

The discovery represents a paradigm shift in Chinese offshore energy exploration. The Bohai Bay Basin was traditionally considered an oil-dominated basin, and the discovery of such a large gas field challenged long-held geological assumptions. According to academic research published in China Petroleum Exploration, the discovery demonstrated that the deep Bozhong Sag has enormous natural gas exploration potential, breaking through the conventional wisdom that the basin could not host large gas fields.

As People’s Daily Science notes, the field is “China’s eastern region’s first large, integrated trillion-cubic-meter gas field,” making it a cornerstone of the nation’s offshore energy strategy and the largest natural gas field discovered in the Bohai Bay Basin to date.

Key Developments

The Phase II milestone was achieved at CNOOC Engineering’s Tianjin Intelligent Manufacturing Base, where the final deck section was positioned into place, completing all three platform main structures and three jackets for the project. The development follows a phased approach: the test area began production in October 2020, and Phase I commenced operations in November 2023.

Phase II introduces an innovative “Production-Transportation-Injection-Electricity” full industry chain model. Natural gas and condensate are collected via wellhead platforms, transported through subsea pipelines to a terminal platform for processing, with separated gas reinjected into the reservoir to maintain formation pressure. A shore power system supports production operations, significantly improving resource utilization and operational efficiency.

According to the China Securities Journal, this integrated approach represents a notable technological advancement in China’s offshore gas field development, setting a new standard for efficiency and resource management.

Analysis and Implications

The completion of Phase II main structures signals that the platforms will soon be installed offshore, bringing the gas field closer to full production. When fully operational, the Bozhong 19-6 field will significantly boost China’s domestic natural gas output, reducing the country’s reliance on imported liquefied natural gas (LNG) and pipeline gas.

China is the world’s largest natural gas importer, and domestic offshore production is a strategic priority under the government’s energy security framework. The project has been explicitly framed as having “significant meaning for safeguarding national energy security, alleviating natural gas supply pressure, contributing high-quality clean energy, and optimizing the energy structure,” according to industry sources cited by Tianjin Pipe Corporation.

The technological model developed in Phase II — integrating production, transportation, reinjection, and shore power — represents a significant advancement in China’s offshore engineering capabilities. This integrated approach could be replicated for other offshore gas fields, particularly as China continues to explore deepwater reserves. The Bozhong 19-6 development is part of a broader trend in China’s offshore energy sector, which has seen milestones including the “Deep Sea No. 1” deepwater gas field entering production in June 2021 and the nearby Bozhong 19-2 oil field being fully commissioned in November 2024.

The project also highlights the growing role of Tianjin as an offshore engineering hub, with the Intelligent Manufacturing Base serving as a center for constructing complex offshore infrastructure. This aligns with China’s 14th Five-Year Plan energy targets, which emphasize expanding domestic production capacity and technological self-sufficiency.

What’s Next

With the main structures completed, the focus now shifts to offshore installation and commissioning of the Phase II platforms. While CNOOC has not announced a specific timeline for full production, the accelerated pace of construction suggests that commercial operations could begin within the next phase of development. Industry observers will be watching for details on production capacity targets and whether Phase III or further expansion plans are in development.

Several outstanding questions remain: What is the total investment value of the Phase II project? How does its production capacity compare to Phase I? And what specific contribution will this field make to China’s overall natural gas production targets under the 14th Five-Year Plan?

The Bozhong 19-6 gas field stands as a testament to China’s growing capabilities in offshore energy exploration and production — a development with implications not only for the country’s energy security but also for global natural gas markets. As China continues to advance its offshore engineering capabilities, the technological innovations pioneered here may well shape the future of the country’s broader energy transition strategy.