Neutron well logging, using instruments equipped with neutron source and detectors (e.g., ³He-tubes, NaI, BGO), plays a key role in lithological differentiation, porosity determination, and fluid property evaluation in the petroleum industry. The growing trend of multifunctional neutron well logging, which enables simultaneous extraction of multiple reservoir characteristics, requiring high-performance detectors capable of withstanding high-temperature downhole conditions, limited space, and instrument vibrations, while also detecting multiple particle types. The Cs₂LiYCl₆:Ce³⁺ (CLYC) elpasolite scintillator demonstrates excellent temperature resistance and detection efficiency, making it become a promising candidate for leading the development of the novel neutron-based double-particle logging technology. This study employed Monte Carlo simulations to generate equivalent gamma spectra and proposed a pulse shape discrimination simulation method based on theoretical analysis and probabilistic iteration. The performance of CLYC was compared to that of common detectors in terms of physical properties and detection efficiency. A double-particle pulsed neutron detection system for porosity determination was established, based on the count ratio of equivalent gamma rays from the range of 2.95–3.42 MeVee energy bins. Results showed that CLYC can effectively replace ³He-tubes for porosity measurement, providing consistent responses. This study offers numerical simulation support for the design of future neutron well logging tools and the application of double-particle detectors in logging systems.

Cement density monitoring plays a vital role in evaluating the quality of cementing projects, which is of great significance to the development of oil and gas. However, the presence of inhomogeneous cement distribution and casing eccentricity in horizontal wells often complicates the accurate evaluation of cement azimuthal density. In this regard, this paper proposes an algorithm to calculate the cement azimuthal density in horizontal wells using a multi-detector gamma-ray detection system. The spatial dynamic response functions are simulated to obtain the influence of cement density on gamma-ray counts by the perturbation theory, and the contribution of cement density in six sectors to the gamma-ray recorded by different detectors is obtained by integrating the spatial dynamic response functions. Combined with the relationship between gamma-ray counts and cement density, a multi-parameter calculation equation system is established, and the regularized Newton iteration method is employed to invert casing eccentricity and cement azimuthal density. This approach ensures the stability of the inversion process while simultaneously achieving an accuracy of 0.05 g/cm³ for the cement azimuthal density. This accuracy level is ten times higher compared to density accuracy calculated using calibration equations. Overall, this algorithm enhances the accuracy of cement azimuthal density evaluation, provides valuable technical support for the monitoring of cement azimuthal density in the oil and gas industry.