A method for determining density based on gamma ray and fast neutron detection using a Cs₂LiYCl₆ detector in...

Area of Science:

• Nuclear geophysics
• Logging-while-drilling (LWD) technology
• Radiation detection

Background:

• Growing demand for radioisotope-free operations in well logging.
• Limitations of current multiple-detector array designs in pulsed neutron-gamma density (NGD) tools for simplification.
• Need for improved instrument design and measurement systems in NGD applications.

Purpose of the Study:

• To propose a novel density measurement method for NGD logging.
• To develop a simplified NGD measurement system using a single detector.
• To enhance density sensitivity and avoid complex instrument designs.

Main Methods:

• Utilized fast neutron-gamma coupled theory for density determination.
• Employed a Cs2LiYCl6 (CLYC) detector for simultaneous neutron-gamma detection.
• Implemented a measurement system with a D-T neutron source and a single CLYC detector.
• Verified the method via Monte Carlo simulations and application in a simulated well.

Main Results:

• Successfully determined formation density using a single CLYC detector.
• Demonstrated avoidance of complex instrument systems and improved density sensitivity.
• Validated the method's applicability through simulations and experimental application in a benchmarked well.

Conclusions:

• The proposed method enables radioisotope-free NGD measurements with a simplified, single-detector system.
• This approach offers enhanced density sensitivity and practical advantages for LWD development.
• The research provides foundational theoretical guidance for future NGD instrument design.