Abstract: Drilling operations in ultra-deepwater and ultra-shallow wells in the South China Sea have short operating time, with riser running/retrieval occupying a significant time portion during drilling operations and incurring high costs. Riserless drilling effectively reduces both operating duration and expenses. However, riserless drilling in deepwater and shallow layers introduces new challenges for logging operations, including surface swells in open waters impacting cables and logging tools, difficulties in tool entry into subsea wellheads, and platform heave and shallow-layer conditions compromising tool sealing stability and operation safety. Through comparative analysis and verification of three existing logging schemes, an innovative riserless wireline logging scheme was developed, featuring casing suspension at the wellhead to isolate shallow-layer swells, remotely operated vehicles (ROV) assisting in precision logging tool deployment in well through real-time positioning and guidance, and enhanced sealing mechanisms with tension warning to ensure tool stability and operation safety. Field applications in the Qiongdongnan Basin of the South China Sea have demonstrated that this scheme has a good effect. It can achieve full coverage of operation projects from conventional logging to fixed-point logging, effectively reduce drilling costs, and ensure the acquisition of geological data, providing technical support for efficient exploration and development in ultra-deepwater and ultra-shallow layers.