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 (COSL) Intelligence Technology Co., Ltd.

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 tackles the global challenge of formation measurement and evaluation in cased wells of complex reservoirs. It innovatively proposes new principles for through-casing array density measurement and synchronous cement–formation measurement, and has developed China’s first independently patented array density logging tool and integrated nuclear physics computation and interpretation platform. The project established a full-chain technical system covering “theory–method–platform–equipment–application”, inventing a new method to eliminate interference from variable media and micro-annuli. It achieves high-precision, quantitative, and simultaneous measurement of both formation and cement, with accuracy reaching an internationally leading standard. The results have been successfully applied in the Bohai, East China Sea, and North China oilfields, significantly improving logging precision and complex reservoir evaluation capabilities. The project has generated remarkable economic and social benefits and plays an important role in promoting efficient unconventional energy development and the localization of high-end well logging equipment.

Main Innovations:

The project overcomes the global problem of “inaccessible, inaccurate, and unreliable” measurements in complex reservoirs by introducing several world-first technologies: First through-casing array density logging instrument, capable of high-precision formation evaluation through casing; New synchronous cement–formation measurement technology, allowing real-time assessment of both layers simultaneously; Integrated nuclear–formation interpretation platform, combining theoretical modeling, simulation, and field data analysis. Together, these innovations form a complete, independent technical system of “theory–method–platform–equipment–application,” with the overall technology reaching the international leading level.

Main Uses and Technical Principles:

Main Uses:
The technology is mainly used for fine reservoir evaluation and dynamic monitoring in deep, offshore, and complex oilfield environments, particularly in cased-hole applications.

Technical Principles:
Based on the original spatial–energy coupling theory, and combining array detection, multi-source signal processing, and adaptive correction algorithms, the technology enables simultaneous, high-precision measurement of cement and formation properties. It supports green, efficient, and intelligent development of oil and gas reservoirs, ensuring accurate reservoir characterization under complex downhole conditions.

Technical Applications:

The independently developed post-casing array density and triple-porosity logging technology and tools effectively fill a major technical gap in the industry. The technology ensures accurate data acquisition under complex drilling conditions, diverse borehole environments, and challenging well trajectories, guaranteeing comprehensive and reliable geological data. Extensive field results show that post-casing density logging data are accurate and high quality, fully meeting the needs for lithological and petrophysical evaluation of clastic rocks, conglomerates, and buried hill formations. By integrating post-casing density and neutron-derived porosity parameters, the technology supports reserves calculation, development plan optimization, and dynamic reservoir management. The triple-porosity combination (density, neutron, and sonic) accurately identifies gas-bearing zones, even under complex conditions, significantly enhancing China’s technical and equipment capabilities in oil and gas exploration and contributing to national energy security.