Decline Curve Analysis in a Naturally Fractured Reservoir with a Finite-Conductivity Fault

Abstract

An analytical solution for constant producing pressure conditions for a well near a nonintersecting finite-conductivity fault, of infinite length in a naturally fractured reservoir, is presented. The solutions for the dimensionless flow rate are based on a model presented by Abaszadeh and Cinco-Ley. In this work the model was extended to include constant producing pressure in infinite systems. Flow along and across the fault plane is considered. It is demonstrated that a graph of for long times produces a straight line with slope -1/4, it is proportional to . Type curves in terms of fault conductivity and diffusivity ratios are presented. Finally, a field pressure-buildup test and production history data from a faulted reservoir that exhibit characteristics predicted by the analytical model are analyzed. The results show that the initial decline could be a key factor in deciding when to change or abandon a well, and for a practical viewpoint, given an initial value to the flow rate, it is important to know the time required to deplete the system composed by the naturally fractured reservoir and the finite conductivity fault.