| Summary: | Due to the potential for using methane hydrates as an energy source, localizing, monitoring and describing hydrate deposit areas are of interest. This has previously been attempted by using acoustic methods and thus information on the relation between the hydrate saturation, SH, and acoustic properties, such as cP , cS (compressional and shear wave velocity, respectively) and P (compressional wave attenuation coe scient) is needed. The overall aim of this PhD thesis is to measure and discuss cP , cS and the change in P ( P ) in ten Bentheim sandstone specimen having di erent initial water saturations, Sw0 as a function of SH, during hydrate growth. In the literature, laboratory studies typically focus on measuring cP and cS in unconsolidated hydrate bearing sediments using the " rst arrival of the pulse," which means that the measurement frequency of the elastic wave is not de ned. Only a few laboratory studies are found by this author to measure acoustic properties for hydrate bearing sediments for de ned frequencies, and only one study is found to report P during hydrate growth. Although one study is found on hydrate bearing consolidated sediments, no laboratory studies are found by this author to measure cP , cS and the change in P for Bentheim sandstone during hydrate growth. In this work, a pressure cell in which hydrates may grow is modi ed so that acoustic measurements can be conducted during hydrate growth. Piezoelectric shear-wave (Swave) and compressional wave (P-wave) transducers are designed and constructed to be used with the solid bu er measurement method and to t inside the pressure cell. Due to the limited space inside the pressure cell, unwanted acoustic re ections from e.g. sidewalls will a ect the measurements. The S-wave transducers transmit both P-waves and S-waves and mode conversion between these may also occur. To measure P-wave or S-waves, short pulses are needed to separate the measurement signal from the other re ected or mode converted signals. To do so, broadbanded transducers are ...
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