The water depth achieved by deepwater drilling in the South China Sea has been increasing annually

and three wells have been already drilled at a depth of more than 2000 meters

and the maximum depth exceeds 2600 meters. The increasing water depth results in the prolonged tripping time for drilling tools during operations in deep water

particularly ultra-deep water

and operational safety risks are increased due to the long-time exposure of drilling tools to deep water for extended periods. To reduce the frequency of tripping in deep water and enhance the efficiency of operations in shallow formations

the paper proposes an efficient "three-in-one" drilling technology for shallow formations in deep water

which is based on the analysis of regional shallow geological and mechanical parameters and practical experience from over 40 deepwater wells drilled in the South China Sea. Through the optimization of wellbore structure design

drill string and tool optimization

jet bit design

and subsea wellhead stability analysis

the "three-in-one" efficient drilling operation mode for shallow formations in deep water has been developed. This technology allows for the completion of the whole wellbore comprising surface conductor

surface casing

and intermediate casing in a single trip through innovative designs of drilling tools and tubular structure

thus simplifying operational procedures

significantly enhancing operational efficiency

and achieving the goal of deepwater drilling. The technology was applied in 10 deepwater wells in the deepwater areas of the South China Sea

such as Baiyun

Liuhua

Liwan

and Kaiping. The application results indicate that the "three-in-one" efficient drilling technology for deepwater shallow formations can reduce tripping operations by two trips compared to conventional jetting methods

by which the drilling efficiency in deepwater shallow formations can be increased by over 50 %

and the exposure time and frequency of drilling tools in deep water is also reduced.