China National Offshore Oil Corporation (CNOOC) has rolled out plans to develop a number of carbon capture and storage (CCS) hubs in southern China’s Guangdong province, where only one offshore project is currently under development.

CCS is seen as crucial for China to achieve carbon neutrality by 2060 and debottleneck its carbon emissions reduction challenges, and offshore CCS is expected to play a key role.

As the largest sedimentary basin in northern part of the South China Sea, the Pearl River Mouth basin also offers the most potential for CCS, according to Qin Jianyu, deputy manager of the technology centre of deep-water engineering, CNOOC Shenzhen.

A recent report issued by the South China Sea Institute of Oceanology shows that deep saline formations at the Pearl River Mouth basin could store up to 136.8 billion tonnes of carbon dioxide.

In Guangdong, CNOOC has mapped out a phased development for CCS, beginning with its first offshore CCS project under development at the Enping oilfield in the Pearl River Mouth basin, to be followed by a few more schemes in the Beibu Gulf of the South China Sea.

CNOOC says the Enping project will be expanded to capture CO2 from petrochemical and power operations at Daya Bay area of Guangdong, 76 kilometres from Hong Kong, and reinject it into geological formations offshore China, but the use of CO2 for enhanced oil recovery at ageing oil wells is also planned.

By 2025, CNOOC intends to capture 1 million tonnes per annum of CO2 through this first scheme, but it is not clear if this figure is on a net basis, nor if the estimate takes into account the increase in emissions from EOR-related output.

Plans include building an onshore CCS hub integrated with supply chains covering capture, transportation and storage in Guangdong.

The ultimate goal is to build a complete CCS industry chain around Guangdong and Hong Kong by 2050.

Guangdong industry emits about 700 million tonnes per annum of CO2 from operations in the Pearl River Mouth Delta region, and the eastern and western part of the province, according to Nanfang Science and Engineering deputy director Li Xusheng.

Meanwhile, 42 petrochemical complexes at Daya Bay region alone emit about 20 million tpa of CO2, according to CNOOC Shenzhen development manager Dai Zong.

A more ambitious plan involves building three more CCS industry clusters outside Guangdong centering around CNOOC’s production hubs in northern China’s Bohai Bay, the Yangtze River Delta region around East China Sea, and Hainan province.

CNOOC has four offshore production bases — Bohai Bay, East China Sea, the Pearl River Mouth basin, and the Qiongdongnan basins — in the South China Sea.

CNOOC has offered glimpses of its efforts to plan ahead to be able to tackle technical obstacles and evaluate commerciality before finalising these schemes, given China’s huge emissions reduction challenge.

To meet China’s carbon-neutrality target in 2060, the country will need to cut up to 1.8 billion tpa of CO2 by 2060, up from expected 10 million tpa in 2027 and 100 million tpa in 2035, according to Li.

Offshore CCS projects

CNOOC will soon commission its first offshore CCS project at the Enping 15-1 oilfield complex in the Pearl River Mouth basin.

The field will produce up to 36,500 barrels per day of oil and capture up to 300,000 tpa of CO2 and reinject it into a reservoir for storage.

The aim is to capture a net 1.46 million tonnes of CO2 at the field — which lies 190 kilometres southeast of Hong Kong in water depths of 80 metres — over the duration of the project.

Li said that three troughs — Wushi, Leidong and Weixi South — in the Beibu Gulf are promising for CO2 storage.

The Wushi trough has potential to store 10.7 billion tonnes, while the Leidong trough is able to store 5.9 billion tonnes of CO2 and the Weixi South Trough has the potential to store 5.2 billion tonnes.

CNOOC is now considering test trapping CO2 from electricity generation and transporting it for reinjection at geological storage sites in the Wushi trough.

The current focus of the study is to capture CO2 emitted from the Datang Leizhou power plant and reinject it into reservoirs at the Wushi oilfield for EOR, which is under development in the Beibu Gulf.

Li, the former vice president of CNOOC Zhanjiang in charge of the Wushi development, said the scheme will be able to store 15 million tonnes of CO2 and enhance oil recovery by 2 million tonnes.

Li’s lab has assessed the prospective geologic storage potential of offshore subsurface depleted oil and natural gas reservoirs and saline formations in the South China Sea. Integration with other carbon capture projects under study in the region is envisaged.

Joint study with Shell, ExxonMobil

CNOOC’s initiative is supported by supermajors Shell and ExxonMobil under a joint study agreement, which commits the trio and local Guangdong authorities to evaluate the potential for world-scale CCS projects to reduce greenhouse gas emissions in the Daya Bay area.

Initial assessments indicate the potential to capture up to 10 million tpa of CO2 from Daya Bay’s industrial sector.

The parties will seek to conduct a joint study to assess the technical solution, develop the commercial model and work with government to formulate enabling policies.

The project could also serve as a model for the chemical industry as one of the first petrochemical projects to be decarbonised.

ExxonMobil has said that CCS is a safe, proven and consistent technology that can enable some of the highest-emitting sectors such as manufacturing, power generation, refining, petrochemical, steel and cement industries to reduce their emissions.

Jason Wong, executive chairman of Shell Companies in China, said the country has “an ambitious decarbonisation path”, aiming to reduce CO2 emissions from about 10 billion tpa to net zero within 30 years.

China has more than 40 carbon capture, utilisation and storage pilot projects with total capacity of 3 million tpa, many of which are small developments associated with EOR.

This capacity will need to be scaled up significantly over the next four decades, and China has yet to offer detailed data on net emissions for such projects, taking into account additional oil production from EOR operations.