Type
ArticleAuthors
Sun, ZhonghaoSantamarina, Carlos

KAUST Department
Ali I. Al-Naimi Petroleum Engineering Research Center (ANPERC)Earth Science and Engineering Program
Energy Resources and Petroleum Engineering
Physical Science and Engineering (PSE) Division
Date
2019-03-15Online Publication Date
2019-03-15Print Publication Date
2019-03Permanent link to this record
http://hdl.handle.net/10754/631114
Metadata
Show full item recordAbstract
Gas migration mechanisms control the release of gas from seafloor sediments. We study underlying phenomena using transparent sediments subjected to controlled effective stress; this experimental approach allows high-resolution real-time monitoring of gas migration through cohesionless granular materials under 3D-boundary conditions. Observed migration patterns depend on the effective stress at the time of injection and the stress history. Gas migration transitions from pore-invasive to grain-displacive when the capillary pressure for air entry ΔPAE is greater than the effective stress σ'. This study focuses on grain-displacive gas migration. The morphology of grain-displacive gas bodies changes with depth as the sediment stiffness G increases and the effect of surface tension γ vanishes: spheroidal gas bubbles form in the near-surface, faceted cavities further down, and eventually open-mode fractures develop at depth. The gas injection pressure is proportional to the effective stress in grain-displacive migration. Pre-loading and overconsolidation cause the rotation of principal stresses and gas-driven openings align with the new minimum principal stress direction. Cyclic loading promotes the upwards migration of gas-filled openings, and there is mechanical memory of previous gas pathways in sediments.Citation
Sun Z, Santamarina JC (2019) Grain-Displacive Gas Migration in Fine-grained Sediments. Journal of Geophysical Research: Solid Earth. Available: http://dx.doi.org/10.1029/2018jb016394.Sponsors
Support for this research was provided by the KAUST endowment. G. E. Abelskamp edited the manuscript. Data sets presented as part of this study are available from the KAUST Repository: http://hdl.handle.net/10754/630965.Publisher
American Geophysical Union (AGU)Additional Links
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JB016394ae974a485f413a2113503eed53cd6c53
10.1029/2018jb016394