Impact of Confining Stress on Capillary Pressure Behavior During Drainage Through Rough Fractures. Issue 13 (15th July 2019)

• Record Type: Journal Article
• Authors: da Silva, Josimar A.; Kang, Peter K.; Yang, Zhibing; Cueto‐Felgueroso, Luis; Juanes, Ruben
• Is Part Of: Geophysical research letters. Volume 46:Issue 13(2019)
• Page Start: 7424
• Page End: 7436
• Publication Date: 2019-07-15
• Subjects: multiphase flow -- fractures -- roughness -- capillary pressure -- self‐organized criticality; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL082744
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: We study, numerically, the behavior of capillary pressure ( P c ) during slow immiscible displacement in a rough fracture as a function of the degree of fracture aperture heterogeneity that results from two distinct mechanisms: normal confining stress and fracture surface correlation. We generate synthetic self‐affine rough fractures at different correlation scales, solve the elastic contact problem to model the effect of confining stress, and simulate slow immiscible displacement of a wetting fluid by a nonwetting one using a modified invasion percolation model that accounts for in‐plane curvature of the fluid‐fluid interface. Our modeling results indicate that the power spectral density, S ( f ), of P c, can be used to qualitatively characterize fracture aperture heterogeneity. We show that the distribution of forward avalanche sizes follows a power law N f ( S f ) ∝ S f − α, with exponent α =2, in agreement with previously reported values for porous media and equal to the expected theoretical exponent for a self‐organized criticality process. Key Points: In‐plane interface curvature impacts signature of capillary pressure during drainage in rough fractures Hierarchical avalanche size distribution is consistent with a system that exhibits self‐organized criticality Power spectrum of capillary pressure suggests increased self‐organization as confining stress increases