dimensional fluid and thermal transport. SUTRA simulates the fluid flow and the pore

pressure changes with time. Once the pore pressures were calculated in SUTRA they

were transferred back into the prism-growth/flow model, which calculates effective

stress, porosity, and permeability before beginning the next loading step.

 During hydrofracture, the model checks for regions that have reached the criteria

for vertical hydrofracture after every seaward advancement of the prism. If pressures

meet the vertical hydrofracture criteria, then the model increases vertical permeability

from the point of lithostatic pressure up to the decollement. If pressures are less than the

assigned criteria for hydrofracture the permeability values are assigned according to

permeability-porosity relationship.

 SUTRA uses a backwards finite-difference scheme which enhances numerical

stability. The large permeability contrast during the introduction of hydrofractures into

the model was challenging for the iterative solver, especially for the thermal transport

simulations. However, by reducing the contrast between the highest and the lowest

permeabilities and increasing upstream weighting for the transport, convergence was

obtained.

 Model Equations

 Combining the mass conservation of fluid with Darcy's law, the following equation

can be written for two-dimensional transient flow:

 K h K a'h Sh
 K X X K2 a Q2 --d (1)


 where Ss is specific storage [L-1], h is hydraulic head [L], x and y are spatial

coordinates, Q is a source term reflecting processes such as loading that affect fluid

volume or pressure [T-1]. The left hand side term accounts for fluid flow into and out of a