Project Title: Advanced Through-Casing Measurement and Application in Complex Reservoirs

Participating Enterprises: University of Electronic Science and Technology of China；China Oilfield Services Limited

Award Received:Technological Invention Award - Gold Award

Achievement Level: International Leading Level

Project Number: ECF-2025-SET-1010

Main Participants: Zhang Qiong, Jin Ya, Sun Zhifeng, Chen Wei, Shan Wei, Qu Wenbo

Expert Review Comments:
International leading level. This project addresses the global challenge of formation measurement and evaluation in complex reservoir cased-hole wells. It innovatively proposes new principles for array density logging through casing and simultaneous cement-formation measurement, developing China's first array density logging tool with independent intellectual property rights and an integrated platform for nuclear physics computation and interpretation. The project established a comprehensive technology chain encompassing “theory-methodology-platform-equipment-application.” It invented novel techniques to eliminate interference from variable media and microannuli, achieving high-precision quantitative characterization of both formation and cement through simultaneous measurement—reaching internationally leading accuracy levels. The achievements have been successfully applied in oilfields across the Bohai Sea, East China Sea, and North China, significantly enhancing logging accuracy and reservoir evaluation capabilities in complex wells. This has yielded substantial economic and social benefits, demonstrating significant importance for advancing the efficient development of unconventional energy resources and the localization of logging equipment.

Main Innovations:

Pioneered cased-hole array density logging and integrated interpretation platform, solving the challenges of “invisible, inaccurate, and unreliable” measurementsin complex reservoirs.

Main Uses and Technical Principles:

Used for precise evaluation of complex reservoirs; based on space–energy coupling, it enables high-accuracy synchronous measurement of formation and cement,supporting green and efficient development.

Technical Applications:

The independently developed post-casing array density and triple porosity logging technology and equipment for this project effectively fill technical gaps in the industry. Under complex drilling conditions, wellbore environments, and wellbore trajectory scenarios, post-casing density logging enables the successful acquisition of critical data, significantly ensuring data integrity. Extensive field measurements demonstrate the accuracy and high data quality of post-casing density measurements, fully meeting the lithological and physical property evaluation requirements for clastic rocks, complex sandstones, and basement formations. Key parameters such as post-casing density and neutron-derived porosity enable this technology to effectively support reserve calculations and development plan adjustments. Furthermore, the application of a three-porosity approach combining post-casing density with neutron and acoustic measurements enables precise identification of gas-bearing characteristics in formations. This serves as a powerful tool for evaluating gas potential in complex well conditions, elevating domestic oil and gas exploration technology and equipment standards while making significant contributions to safeguarding national energy security.