Permeability of wormholes created by CO2-acidized water flow through stressed carbonate rocks

Abstract

Sequestration of CO 2 relies on the storage capabilities of the deep geologic setting throughout the lifetime of the storage activity. Preferred storage horizons are largely composed of sandstone, which is considered to be chemically inert to the injected CO 2. Carbonate rocks and carbonate zones existing as seams or lenses in sandstone formations are, however, prone to chemical alteration during reactive flows of CO 2-acidized water that can be created by the mixing of the injected CO 2 with either fresh or saline water present in a storage horizon. Reactive flows can erode the fabric of carbonate rocks leading to the creation of high permeability pathways that are referred to as wormholes. The paper first examines the generation of wormholes in cylindrical samples of calcium carbonate-rich Indiana Limestone that are subjected to geostatic stress states representative of deep sequestration sites. The leakage potential of the wormhole is examined by appeal to computational fluid dynamics simulations of Stokes' flow in wormhole features and an elementary approach involving Stokes' flowbased hydraulic diameter concept in cylindrical pathways with deviating segments, representing the passages for flow in a wormhole.

An immersed phase field fracture model for microporomechanics with Darcy–Stokes flow

“…Geomaterials such as carbonate rocks, sandstone, or limestone often contain geometrical features such as cracks, joints, vugs, or cavities. When the defects are partially or fully saturated with the pore fluid, the geometry of the features may affect effective stiffness, permeability, water retention characteristics, and drained or undrained shear strength of the material (Juanes et al, 2006;Sun et al, 2011b;Kang et al, 2016;Suh et al, 2017;Selvadurai et al, 2017;Wang and Sun, 2017;and Sun and Wong, 2018). Furthermore, brittle fracture in materials that possess geometrical features may lead to the pore fluid in cavities migrating into the flow channels and causing flow conduits that lead to often undesirable outcomes.…”

Influence of mineralization and injection flow rate on flow patterns in three-dimensional porous media

“…Consequentially, Xray tomography has become a standard tool 1 for all experiments where the interaction between different solutions inside a porous matrix is studied 16 . Important examples, especially in the context of CCS techniques, are X-ray tomography studies on how carbonate rocks dissolve due to the injection of CO 2 saturated brine [17][18][19][20][21][22][23][24][25][26][27][28] . The same brine with added H 2 SO 4 not only dissolves carbonate rocks but also precipitates gypsum 29 .…”

Hydrodynamics and geochemistry at multiple scales : characterizing preferential flow-paths and wormholes in evaporitic sediments

“…The safety of storage due to CO 2 leakage through the caprock can compromise the geological trap (Lombard, J.M. et al, 2010;Kampman et al, 2014;Selvadurai et al, 2017). In oil and gas fields, stimulation treatments with acid injection are often employed to enhance oil and gas recovery (EOR).…”