Gas bubbles are widespread in seafloors and lakebeds and typically found in shallow and fine-grained sediments. Sediment properties control gas nucleation and gas migration. Gas migration and pathways have been studied mostly in clean coarse particles or fine-grained matrices. Nevertheless, both cases show very distinct geo-behaviors. Pore habit is defined by the counteracting effects of effective stress and pore-throat-dependent capillary pressure. In this article, we explore gas nucleation by CO₂ gas exsolution and its consequent gas-driven fractures (open-mode discontinuities) or pore invasion in binary sediments as a function of fines content (FC). We conducted physical test analogies for different FC subjected to gas exsolution. Our results highlight that the pore habit of gas in gassy sediments depends on its capability to invade a neighboring pore (capillarity) and burial depth (effective stress). We show that the load dominant fraction in binary soils can be used to estimate the dominant pore throat size. We then proposed a robust methodology to predict the pore habit of gassy sediments from its properties as defined in recent developments in soil behavior and characterization. Finally, we applied it to a real case offshore Vancouver Island.

中文翻译：

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瓦斯沉积物中瓦斯的孔隙习性

气泡普遍存在于海底和湖床中，通常存在于浅而细颗粒的沉积物中。沉积物特性控制气体成核和气体迁移。大部分在干净的粗颗粒或细颗粒基质中研究了气体迁移和途径。但是，这两种情况都显示出截然不同的地理行为。毛孔习性是由有效应力和依赖孔喉的毛细血管压力的抵消作用定义的。在本文中，我们探讨了CO _2引起的气体成核气体逸出及其随之而来的气体驱动裂缝（开放模式的不连续性）或二元沉积物中的孔隙侵入随细粒含量（FC）的变化而变化。我们对经受气体排泄的不同FC进行了物理测试类比。我们的结果表明，气态沉积物中气体的孔隙习性取决于其侵入邻近孔隙的能力（毛细作用）和埋藏深度（有效应力）。我们表明，二元土壤中的负荷优势分数可用于估计优势孔喉尺寸。然后，我们提出了一种强大的方法，可以根据土壤行为和特征的最新发展中定义的性质，预测气态沉积物的孔隙习性。最后，我们将其应用于温哥华岛近海的真实案例。