This article summarizes the four main stages of the development of international ocean scientific drilling: deep sea drilling project, international ocean drilling program, integrated ocean drilling program and international ocean discovery program, and introduces the main scientific achievements obtained during each stage. China also participated in the above stages, leading four voyages across three ocean scientific drilling projects, and achieved a series of scientific achievements in the South China Sea. The development of international ocean scientific drilling is closely related to the development of ocean drilling vessels. The development of worldwide ocean scientific drilling equipment is chronologically introduced with a focus on the technical characteristics of China's first ocean scientific drilling vessel, the “Mengxiang”. Finally, the development of the ocean scientific drilling technology is analyzed based on the development history of the ocean drilling and the update and iteration of the ocean drilling vessels. It can provide references for the development of the international ocean scientific drilling.

Deepwater drilling unit plays an important role in the exploration of marine resources. In the exploration of marine oil and gas resources, it is widely used for the evaluation of the oil and gas resource reserve, well completion, workover and oil testing operation. Whereas in the exploration of marine mineral resources, it is the key equipment to evaluate the reserves and grade of polymetallic sulfide resources. The typical stages and equipment of marine resource exploration are introduced in this article. Focusing on the drilling unit for deepwater resource exploration, it introduces the state-of-the-art of the drilling unit at home and abroad, analyzes the design points of typical deepwater drilling units, and prospects the technical development trend of the deepwater drilling unit. In the design of the deepwater drilling unit, it focuses on the comprehensive balance of the overall performance, general arrangement, weight control, structural performance and integrated design of main systems. At the same time, special problems caused by different ship types should also be considered, such as the air gap analysis and key structural node design of the semisubmersible drilling unit, and the impact of the moonpool of the drilling ship on the overall performance. With the steady progress of the deepwater resource exploration, future deepwater drilling units will make breakthroughs and progress in the intelligent technology application, non-riser mud closed circulation technology, green energy-saving drilling rigs, high-efficiency coring technology and polar environmental adaptability.

The influence of the shape and the size of the moonpool on the vulnerability criteria assessment of the parametric roll and the excessive acceleration in the second generation stability has been analyzed for a drillship. This article considers the drillship with three moonpools of different opening shapes and different sizes to verify and analyze whether the drillship meets the second generation intact stability criteria under development. The analysis results indicate that the variation in the shape and size of the moonpool can affect the parameters of the vulnerability criteria of the parametric roll and the excessive acceleration for the drillship. The drillship with the moonpool of the shapes and sizes considered in this study can meet the criteria requirements. It can provide reference for the design of the drillship's moonpool.