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infiltration method was measured. Sand, the pores, and the <strong>hydrate</strong> were identified, and the<br />
porosity and the saturation were calculated. When these calculated values were compared<br />
with the measured result, good correspondence was obtained. These methods were effective<br />
as the frame structure evaluation method for artificial MH sediment and for the natural core<br />
sample. Also, the dissociation process was observed by using the micro focus X-ray CT. As a<br />
result, the change in the pore distribution was observed with an increase in the temperature.<br />
Figure 4. Micro Focus X-ray CT image of Natural Core<br />
Sample of MH Sediment<br />
PREPARATION TECHNOLOGY DEVELOPMENT OF ARTIFICIAL HYDRATE<br />
SEDIMENT<br />
The <strong>gas</strong> infiltration method that pressurized wet sand by methane <strong>gas</strong> and a compaction<br />
method that mixes the <strong>gas</strong> <strong>hydrate</strong> particle and the sediment sand were developed. The size of<br />
artificial MH sediment was prepared to be similar to that of a natural core. In developing the<br />
method of preparation of artificial sediment, the aim was to be able to duplicate the macro<br />
properties of a natural sample and, if possible, to control of the micro-structural properties to<br />
equal those of a natural sample. In addition, the method should be simple, and also be able to<br />
make a large quantity in a short time. The porosity and the MH saturation were analyzed from<br />
the mass balance both before and after reaction and the bulk density to optimize the<br />
manufacturing condition. Moreover, the uniformity of the MH distribution was evaluated by<br />
the amount of the <strong>gas</strong> and the water contents measurement according to the stratification of<br />
the sample.<br />
There are two kinds of sand used to make artificial MH sediment, one replicates the grain size<br />
in the Toyoura silica sand and the other the Mallik core. The latter is a mixture of commercial<br />
silica sand. The compaction method that mixes the methane <strong>hydrate</strong> particles with the<br />
sediment and pressurizes it has the advantage that an artificial sample can be more easily<br />
made as compared with the <strong>gas</strong> infiltration method. Moreover, it is easy to control the volume<br />
ratio of MH, and it is especially suitable for various experiments in which a parameter is the<br />
MH volume ratio. As a result, a controlling technology of saturation and porosity was<br />
established. The equipment for artificial core production is shown in Figure 5.<br />
New Energy Resources in the <strong>CCOP</strong> Region - Gas Hydrates and Coalbed Methane 93
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