Study and practice of wireline logging technology in open sea area for ultra-deep water and ultra-shallow exploration wells

Abstract:

The operation cost can be reduced effectively in open sea duing the ultra-deep water drilling. However， due to the influence of ultra-deep water and ultra-shallow （“double ultra” for short） environment， it faced with difficulties and challenges such as the swaying of cable logging instruments caused by shallow water surge， the difficulty of “entering hole” of cable testing instruments and the hidden safety problems of down-hole operation. In this case， the 20in casing is used to seal off the shallow surge to form an effective sealing. Making full use of the underwater robot to ensure the success of the instrument to “get into the hole”； The speed of the instrument is strictly controlled， and the dual monitoring mode of “ROV underwater + platform control panel” is adopted to ensure the safety of operation. A pilot test was made in several “double ultra” exploration wells in Qiongdongnan Basin， South China Sea， and several wireline logging operations were successfully carried out， detailed logging data were obtained， and operating costs were greatly reduced. This operation practice accumulated valuable experience for subsequent ultra-deep open sea operations， and provided a powerful technical solution for offshore oil and gas exploration and development to increase the reserves and production， reduce costs and increase efficiency.

Key words:exploration well for ultra-deep water and ultra-shallow formations;open sea;wireline logging;underwater robot