Numerical investigation on acidic hydrothermal reactive flow in fractured rocks using a modified LBM model

Abstract

In this study, a geochemical lattice Boltzmann model is developed to model multi-component reaction flow in porous media at the representative elementary volume (REV) scale. Then, we use the modified model to simulate the acid seafloor hydrothermal transport process (13.2 MPa, 603–631 K) with dissolution in fractured rock at the REV scale. In addition, we investigate the effect of the hydrothermal inlet flow rate (v = 0.01, 0.025, 0.05), Rayleigh number (Ra=1×106,5×106,1×107) and permeability (10−14, 10−13, 10−12m2) on the fluid flow behaviour in a vertical fractured porous media with the porosity (ε=0.2). Under the same acid flux (4×10-5mol/s), increasing the inlet velocity (from 0.01 to 0.05) and increasing the Ra number (from 1×106 to 1×107) elevate the fracture dissolution degree by 1.6% and 6.9%, respectively. Furthermore, we numerically explain the formation mechanism of several typical shapes (pyramidal, cylindrical and conical ducts, with a dome observed by experiments) of vent conduits at 1786–7090 m for the dissolution reaction, which can facilitate the understanding of hydrothermal energy transportation and mining.