Key Drilling Techniques of Liwan22-1-1 Ultra-Deepwater Well in East of South China Sea

Liwan 22-1-1 ultra-deep water well is located in the eastern section of the South China Sea, with an operating water depth of 2 199.35 m, and is the deepest deep water well in China. Addressing to technical challenges of ultra water depth, low seabed temperature, extremely narrow safety pressure window, poor diagenesis of shallow stratum, complicated mechanical behaviors of riser and drill string, mature drilling engineering design and precise on-site management had been implemented, and some key technical measures including jetting conductor driving in, FLAT-PRO constant rheological synthetic drilling fluid, low temperature early strength cement slurry surface casing cementing, drilling fluid equivalent circulation density (ECD) monitoring while drilling, etc, had been adopted to fulfill the drilling safely and efficiently, which established the record of shortest drilling cycle under the same water depth in the world, and achieved an excellent project engineering quality. The successful drilling of Liwan 22-1-1 ultra-deep water well marked a major breakthrough in China's ultra-deep water drilling technology. It not only accumulated valuable experience for China's ultra-deep water well drilling, but also promoted and guided the development of ultra-deep water drilling technologies across the globe.