Abstract

Characterization of naturally fractured reservoirs is important for numerical simulation of processes. The mass transfer coefficients are important for simulation of the fracture reservoir. But currently used mass transfer coefficients (G-K, Warren-Root) in the simulators are based on the assumption of pseudo steady-state condition in the matrix blocks. In this research, the advective-dispersive lumped mass transfer coefficient for divergent radial solute transport in fractured rocks is investigated by using the rock matrix blocks` material balance equation.

Based on this model, we find that the Sherwood number demonstrates a transient behavior and then stabilizes at a constant value. Shape of the rock matrix blocks has very clear impact on the Sherwood number; the higher number of fracture planes, the larger contact area for the solute penetration, and consequently higher Sherwood number. Different geometries of the rock matrix blocks also have their impact during transient and stabilized periods. Dispersivity plays an important role in the mass transfer mechanisms and affects the Sherwood number in the field investigations. The condition, in which dispersive solute transport can be neglected, is at high Peclet number (Pe > 105) and small scales of studies (r_D < 3).