Abstract

Laboratory based research on the physical properties of gas hydrate hosting sediment matrix was carried out on the non-pressurized hydrate-bearing sediment samples from the Chinese Guangzhou Marine Geological Survey 2 (GMGS2) drilling expedition in the Pearl River Mouth (PRM) basin. Measurements of index properties, surface characteristics, and thermal and mechanical properties were performed on ten sediment cores. The grains were very fine with a mean grain size ranging from 7 to 11 μm throughout all intervals, which provide guidance for the option of a screen system. Based on X-ray Computed Tomography (CT) and SEM images, bioclasts, which could promote hydrate formation, were not found in the PRM basin. However, the flaky clay might be conducive to hydrate formation in pore spaces. The measured sediment thermal conductivities are relatively low compared to those measured at other mines, ranging from 1.3 to 1.45 W/(m·K). This suggests that thermal stimulation may not be a good option for gas production from hydrate-bearing sediments in the PRM basin, and depressurization could exacerbate the problems of gas hydrate reformation and/or ice generation. Therefore, the heat transfer problem needs to be considered when exploiting the natural gas hydrate resource within these areas. In addition, the results of testing the mechanical property indicate the stability of hydrate-bearing sediments decreases with hydrate dissociation, suggesting that a holistic approach should be considered when establishing a drilling platform. Both the heat-transfer characteristic and mechanical property provide the foundation for the establishment of a safe and efficient production technology for utilizing the hydrate resource.

Highlights

  • As a potential alternative strategic energy source and for the possible impact on the global climate, natural gas hydrates have aroused worldwide attention [1,2,3,4,5]

  • Investigation on the physical properties of hydrate-bearing sediments hasthe a huge stability of deposits, which leads to a risk of submarine landslide [13,14,15]

  • The DS09-1 to high plasticity” or MH, consistent with diatomaceous silty clay. These results indicate that the sample, which is from a different site, is classified as either OH, i.e., “organic clay of medium to high sediments in this region have a relatively low plastic index when compared with other regions plasticity” or MH, consistent with diatomaceous silty clay

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Summary

Introduction

As a potential alternative strategic energy source and for the possible impact on the global climate, natural gas hydrates have aroused worldwide attention [1,2,3,4,5]. Hydrate-hosting medium, such particle size, thermal conduction characteristics, and particle mechanical properties, are important elements for these assessments [25,26]. Interaction, further resulting in a variety of geological disasters including sediment deformation, production platform collapse, and submarine slope failure [34,35] Such information about hydrate reservoirs can be approximated from regional geophysical investigations and refined by direct geological and geochemical studies of cored sediments from a drilling well. Data on the physical properties of these samples could aid in the analysis of corresponding field data and advance our understanding of hydrate occurrence and reservoir characteristics, further providing basic data for the design of drilling wells and the optimization of production technology

Specific Gravity
Water Content
Grain Size Distribution
Pore Characteristics
As incremental are shown in Figure
Microstructure Observation
Microstructure
Thermal
Method
Mechanical Properties
Sediment
Discussion
Soil Types and Classification
Conclusions
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