Leaky Fault Model

This model simulates the transient flow due to a well located near a leaky (finite-conductivity) fault in an infinite-acting two-zone composite reservoir.

The model accounts for transient flow within the fault as well. The formulation considers a line sink well located in a two-zone reservoir, separated by a finite-conductivity fault. The width of the fault is neglected for simplicity when developing the solution, except in the definition of the fault conductivity. The fault is characterized by two parameters:

1. dimensionless fault conductivity (FCD)

2. skin across the fault (sfault).

Note that these parameters are always positive. Dual porosity is not supported in this model.

Based on the definitions mentioned above, the pressure drop along the fault length is due to the fault conductivity (FCD), and the pressure drop across the fault is due to skin (sfault). Thus, various fluid flow behaviour between the reservoir zones can be modeled by adjusting these parameters accordingly. For example, fluid flow from a reservoir region far away from the wellbore to the other reservoir region can be modeled using a highly conductive fault (high FCD), or a no-flow boundary could be modeled by setting FCD to zero and sfault to a high value.

Note:

Due to the nature of the mathematics involved in this model, the computational time is substantially more than in other models.

References

"Analytical Solution to the Transient-Flow Problems for a Well Located near a Finite-Conductivity Fault in Composite Reservoirs", N.M. Anisur Rahman, M.D. Miller and L. Mattar, SPE Paper 84295 for Presentation in SPE Annual Technical Meeting and Exhibition, Denver, CO (October 2003).