Relationship between acoustic properties and hydrate saturation

Abstract

Geophysical prospecting method still plays an important role in gas hydrate explorations and quantifications. Many velocity models have been constructed to relate elastic velocities with hydrate saturations in the hydrate-bearing sediments. Unfortunately, it is found that the results predicted by these models are quite different. Observations on relationship between gas hydrate saturation and elastic velocities are needed to validate these models. Since the data of hydrate saturation in field exploration is insufficient, experimental methods to obtain the relationship between hydrate saturation and acoustic properties are thought to be economically and effectively. In this chapter, gas hydrate has been formed and subsequently dissociated in both consolidated sediments and unconsolidated sediments, respectively. The acoustic properties of gas hydrate-bearing sediments are investigated by an acoustic detection. Simultaneously, hydrate saturations of the host sediments are measured by time domain reflectometry (TDR). With the experimental data, we verified seven velocity models (e.g., BGTL, Biot-Gassmann theory by Lee) that can predict velocities of both hydrate-bearing consolidated and unconsolidated sediments.