Accurate Estimation of Hydrate Saturation Based on Dielectric Responses of Hydrate-Bearing Sediments

Abstract

Summary The accurate evaluation of hydrate saturation not only can provide references for hydrate resources assessment but also help to monitor hydrate decomposition that might cause disasters. The dielectric properties can be employed to efficiently estimate hydrate saturation. However, the correlations between dielectric properties and hydrate saturation are still poorly understood. To obtain such reliable relationships, we first adopt a simulation method based on the three-dimensional finite difference model and digital core technology to calculate the relative permittivity of hydrate-bearing sediments with varying hydrate saturations and micro-distributions and sediment porosities at the frequency of 1 GHz (the frequency of the most dielectric tools). We find that the relative permittivity can be slightly affected by hydrate micro-distribution and increases with increasing sediment porosity. We also find that the relative permittivity decreases exponentially with increasing hydrate saturation, and the two coefficients of the exponential correlation are dependent on sediment porosity. Based on the results, we established the correlations between relative permittivity and hydrate saturation in sediments with different porosities and hydrate morphologies. The hydrate saturation in the Mount Elbert Well is successfully estimated using the obtained relationship. The study provides a reliable tool for the accurate estimation of hydrate saturation in marine sediments.