A Core-Constrained, Scale-Matched Electroacoustic Fusion Method for Gas Hydrate Saturation Estimation: A Case Study of Well GMGS5-W08

Clay-surface conduction in fine-grained, weakly consolidated marine sediments, together with the scale mismatch between core and logging observations, often causes resistivity- and acoustic-based estimates of gas hydrate saturation to diverge. For Well GMGS5-W08, we develop a core-constrained, scale-matched electroacoustic fusion method (CC-SMEF) for gas hydrate saturation estimation. The method derives a low-frequency clay background from gamma-ray and core clay data. An optimizable vertical window then summarizes the logs around each core reference depth as robust neighborhood features. A low-dimensional, regularized kernel map integrates deep resistivity, P-wave velocity, gamma ray, and the clay background on this common representation scale. Chlorinity-derived saturation provides the geochemical reference, and the model was compared with the Archie and Simandoux methods at all reference points and with the isotropic three-phase acoustic method at available matched depths. Pointwise leave-one-out evaluation indicated lower observed error than Archie, although the uncertainty interval included no improvement and explanatory capability remained moderate. The fixed-parameter ablation is exploratory. Under the stricter four-block protocol, saturation-model tuning and fitting were restricted to training blocks while the clay background remained calibrated from all 22 core clay measurements; CC-SMEF RMSE was 17.89 percentage points versus 15.87 for Archie, so superiority in held-out-depth prediction was not established. CC-SMEF is therefore interpreted as a local interpolation framework for the represented W08 intervals; application elsewhere requires independent calibration and validation.