Real-field core sampling and analysis

Gas hydrates are sensitive to pressure, temperature, and chemical condition changes. Although it is possible to collect gas hydrate reservoir data with logging while drilling techniques at in situ conditions, gas hydrate core samples are essential for better reservoir and core analysis. These samples should reflect original conditions. In this chapter, the coring technology for gas hydrates is discussed. Different types of gas hydrate coring techniques (i.e., pressure core sampler, pressure core barrel, pressure–temperature corer, hybrid pressure core sampler, high pressure–temperature corer, HYACE rotary corer, Fugro pressure corer, and Fugro rotary pressure corer) and their field applications are analyzed in detail. As the core samples representing in situ reservoir conditions are collected, their laboratory analyses are made. In this section of the book, the geomechanical, geochemical, and geological analyses of gas hydrate samples are given. In geomechanical analysis, the experimental setup investigating the strength of gas hydrate core samples in situ conditions is explained. In the geochemical and geological analysis of gas hydrate core samples, the applications and importance of source gas analysis, porewater analysis, grain size analysis, lithology analysis, and gas hydrate structure analysis are summarized. The determinations of gas hydrate reservoir properties (i.e., porosity, gas hydrate saturation, permeability) from these core analyses are discussed by using real-field data. Recently, the imaging technologies and X-ray computed tomography have become important in order to determine gas hydrate properties (porosity, permeability, gas hydrate saturation) and their distribution in porous. These technologies are also discussed in this chapter of the book.