One-dimensional numerical model for formation and long-term evolution of focused-fluid escape systems in marine environments

Overview This repository contains a one-dimensional numerical model written in MATLAB for simulating the formation and long-term evolution of focused fluid escape systems in marine environments. The model captures the coupled processes of fracture initiation and propagation, together with subsequent multiphase flow (liquid water and free gas) and multicomponent reactive transport (e.g., methane hydrate formation). Fracture networks connecting deep fluid sources to the seafloor are generated by overpressure-driven hydraulic fracturing. These networks are represented as two orthogonal sets of vertical, parallel plates. Overpressure is driven by a constant fluid flux imposed at the lower boundary. A detailed description of the model and its applications can be found in: “Formation and Long-Term Evolution of Focused-Fluid Escape Systems in Marine Environments.”, which is submitted to Journal of Geophysical Research: Solid Earth in 2026. Model Inputs Key model parameters are defined in initialization.m and include: Bottom water flux (qw) Bottom gas flux (qg) Geothermal heat flux (qt) Salinity of injected brine (Cl_Bottom) Fracture properties: Maximum aperture (w0) Fracture spacing (S_frac) Fracture compressibility (C_frac) Seafloor temperature (surf_T) Water depth (seafloor) Model Outputs The model outputs the depth-dependent evolution of key physical and chemical variables, including: Water pressure (pw) Effective stress (eff_stress) Temperature (T) Brine salinity (cl) Dissolved methane concentration (cm) Gas saturation (sg) Water saturation (sw) Methane hydrate saturation (sh) Fracture aperture (w_frac) Fracture permeability (kx) Outputs are periodically saved as .mat files and printed to the console. Usage The model is executed from: Main_loop.m The default configuration reproduces Case 1 from the associated publication, in which a constant water flux is applied at the bottom boundary with a brine salinity of 16 wt.%.