【Ten Years of Rapid Development in Chemical Engineering Equipment】1339–2021: China’s first domestically produced underwater emergency well sealing device successfully tested in deep-water conditions

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On August 9, 2021, the first domestically developed underwater emergency well sealer, developed under the leadership of CNOOC, successfully passed its sea trials in the deep waters of the South China Sea, achieving complete success in accordance with the planned objectives. This technology fills the technical gap in China’s field of developing related emergency equipment, and will significantly enhance China’s capabilities for emergency response and rescue in marine oil and gas production. Uncontrolled well blowouts are the most serious accidents in oil and gas exploration and production, capable of causing significant property losses and environmental impacts. The underwater emergency well sealer is currently an effective method used by the global offshore oil industry to deal with well blowouts. In use, it is like placing a multi-functional lid on a gushing volcano crater that can completely seal off any overflow. The key factor that enabled the effective containment of the major oil spill that occurred in the Gulf of Mexico in the United States in 2010 was the use, for the first time, of the most advanced underwater emergency well sealers available at that time. It is reported that underwater emergency well sealers have a complex structure and high reliability requirements, representing a **reflection of the capability to develop marine emergency equipment. By the end of 2020, there were only 20 such devices worldwide, and the number of those capable of independently developing and manufacturing this type of equipment was **very limited**. The underwater emergency well seal completed its sea trials is capable of operating at depths of up to 3,000 meters; its volume is more than twice that of the underwater gas production tree used in deep-water oil and gas extraction, and its total weight exceeds 130 tons. The design, development, manufacturing, and testing of this underwater emergency well sealer were all carried out domestically, granting it complete independent intellectual property rights. It integrates technologies such as mechanical manufacturing, hydraulic control, data monitoring, information transmission, and ROV intervention. It has functions such as well shut-in, flow diversion, well killing, dispersant injection, and release of trapped gases. It is reported that this underwater emergency well sealer will be stored at the logistics support bases for offshore oil and gas exploration and development along China’s coast. Its operating cost is 40% lower than that of similar foreign equipment, and it offers a significant advantage in terms of emergency response time, providing reliable equipment support for the efficient handling of emergency oil and gas well blowout incidents in China.