Key points are not available for this paper at this time.
The dynamic evolution of permeability during depressurization-driven production plays a critical role in determining the deliverability of natural gas hydrate (NGH) reservoirs. The reliability of nuclear magnetic resonance (NMR)-based permeability models fundamentally hinges on the accurate determination of the transverse relaxation time cutoff (T2 cutoff, T2C). However, conventional empirical approaches for T2C determination perform poorly in fine-grained sediments and hydrate-bearing formations, posing a major bottleneck to the broader application of NMR techniques. To overcome this limitation, this study introduces a fully automated and physically interpretable framework for Automated Dual T2 Cutoff Determination via Wavelet-Gaussian Decomposition, termed ADWD. This method combines multiscale wavelet peak detection with multilog-Gaussian spectral fitting to objectively identify clay-bound and free-fluid T2C values. Building on these objectively derived fluid partitions, we develop a physically interpretable permeability model (KADWD) that integrates effective flow porosity and bound porosity to reflect pore-structure controls on fluid transport, and field validation shows that our model significantly outperforms classical Coates and SDR models in both hydrate-bearing and hydrate-free intervals. In addition, an ADWD flow-through critical transition criterion is proposed to facilitate the recognition of critical low-permeability transitions. Overall, this study overcomes the applicability limitations of traditional T2C selection and permeability modeling, providing a more reliable petrophysical evaluation tool for assessing the development potential of NGH and other unconventional reservoirs, with strong implications for both theoretical advancement and engineering practice.
Shi et al. (Mon,) studied this question.