Preferential Mode of Gas Invasion in Sediments: Grain-Scale Mechanistic Model of Coupled Multiphase Fluid Flow and Sediment Mechanics.
A. K. Jain and R. Juanes. Journal of Geophysical Research, 114, B08101 (2009), doi:10.1029/2008JB006002. (pdf)
This movie shows the propagation of a fracture during gas invasion into fine-grained media, as predicted by our grain-scale model. The grains, assumed to be spherical, are shown in yellow. The initial configuration is obtained by settling the particles and compacting them to a desired confining stress. Initially, the pack is filled with brine. At time 0, gas invades a pore at the bottom of the sample. From the initial configuration, the gas pressure is allowed to increase. It can invade the pores either by overcoming the capillary entry pressure, or by moving the grains. Pores that have been invaded by gas are denoted with a blue circle. The maroon lines indicate compressive forces between grains. This network of compressive forces changes drastically with the evolution of the fracture. The green lines indicate tension between grains, caused by capillary forces that hold the grains together. The network of tension forces also changes with time, as the gas invades into the sediment.