The coupled multiphase flow and transport problem is solved by the finite e
lement method, using linear three-dimensional tetraeder elements. The three
-phase flow problem is solved simultaneously for the fluid pressures. The s
trong nonlinearities are treated with a Newton-Raphson iteration scheme wit
h relaxation. Due to the kinetic of interphase mass transfer and reactions,
the equations for water, gas, and solid phase concentrations are strongly
coupled. Therefore, both transport equations for water and gas are solved s
imultaneously, while the equation for the solid phase is solved directly. T
he numerical model was tested with analytical, quasi-analytical and other n
umerical models. After the verification first applications were performed.