Estimation of Gas Hydrate Saturation Based on Resistivity Logging and Analysis of Estimation Error

Gas hydrate saturations can be estimated from the Archie equation and the estimation error is dependent on the porosity,saturation factor and Archie's parameters.From the crossplot between density porosity and formation factor of site SH2 in Shenhu area,the Archie parameters were calculated based on the water-saturated sediments.Gas hydrate saturation estimated from isotropic resistivity has an average value of 24% with a maximum value of 44%.The distribution of gas hydrate is heterogeneous in vertical.Chloride anomalies in the core samples show that the average saturation is about 25% in the pore space with a maximum value of 48%,and the thickness of gas hydrate is about 25 meters.The results show that gas hydrate saturations estimated from resistivity data by using the environment parameters in Shenhua area are similar to those estimated from chloride anomalies.The value of gas hydrate saturation estimated from resistivity data depends on the parameters of Archie parameters and the gas hydrate exponents.