On August 30, China National Offshore Oil Corporation (CNOOC) announced that China’s cumulative production from offshore heavy oil thermal recovery has surpassed 5 million tons. This marks a pivotal advancement in the large-scale application of China’s offshore heavy oil thermal recovery technology system and core equipment, establishing China as the world’s first nation to achieve large-scale thermal recovery development of offshore heavy oil.
According to reports, heavy oil accounts for approximately 70% of the world’s remaining oil resources, making it one of the primary targets for oil-producing nations seeking to increase production. For high-viscous heavey oil, the industry primarily employs thermal recovery methods for development. The core principle involves injecting high-temperature, high-pressure steam into the reservoir. This heating process reduces the viscosity of the heavy oil, transforming it into a more fluid, easily extractable “light oil.”
China ranks among the world’s top four producers of heavy oil, boasting abundant heavy oil resources. Proven reserves of high-viscosity heavy oil requiring thermal injection for offshore development exceed 600 million tons, accounting for approximately 20% of China’s total proven heavy oil reserves. This represents significant development potential. Continuously advancing the conversion of heavy oil reserves into production holds vital importance for intensifying domestic oil and gas exploration and development efforts.
Heavy oil is a type of crude oil characterized by high viscosity, high density, poor fluidity, and a tendency to solidify, making it difficult to extract. Compared to onshore oilfields, offshore platforms operate in confined spaces with high costs. The large-scale thermal recovery of heavy oil faces dual challenges in both technical equipment and economic viability, recognized by the industry as a world-class challenge.
China’s offshore heavy oil thermal recovery operations are primarily concentrated in the Bohai Sea, where multiple major thermal recovery fields have been established, including Nanbao 35-2, Luda 21-2, and Jinzhou 23-2. By 2025, thermal recovery production of heavy oil had surpassed 1.3 million tons, with annual output expected to surge to 2 million tons.
To efficiently and economically tap into heavy oil reserves, CNOOC has continuously carried out scientific research and technological breakthroughs. It innovatively proposed the “fewer wells with higher production” theory for thermal recovery development, and adopted a development model featuring large well spacing with “high-intensity injection-production, high-dryness steam, and synergistic efficiency of multi-component thermal fluids”. By injecting high-calorie steam supplemented with various gases and chemical agents, along with supporting high-fluid-volume and efficient lifting technologies, CNOOC has further increased single-well production. This has successfully solved problems such as low thermal recovery productivity and high heat loss, significantly improving the heavy oil recovery rate.
It is reported that to address the complex high-temperature and high-pressure working conditions of heavy oil thermal recovery wells, CNOOC has successfully developed world-leading integrated injection and production equipment that can withstand 350 degrees Celsius. It has also independently developed miniaturized and efficient heat injection equipment, downhole safety control systems, and long-term sand control devices. It has also designed and built the world’s first mobile heat injection platform – “Recai No.1” or “Thermal Recovery No.1”, filling a gap in China’s offshore heavy oil thermal recovery equipment field.
With the enrichment and refinement of thermal recovery technology systems for heavy oil and deployment of key core equipment, China’s offshore heavy oil thermal recovery capacity has accelerated steadily, achieving a breakthrough in reservoir mobilization. In 2024, China’s offshore heavy oil thermal recovery production surpassed the one-million-ton milestone for the first time. To date, cumulative production has exceeded 5 million tons, marking the realization of large-scale offshore thermal recovery of heavy oil.