Most of the theoretical work on decline curve analysis with non-laminar flow in the reservoir consider either a dry gas or liquid flow in an homogeneous system. The purpose of this work is to analyze decline curves considering non-Darcy flow effect in the reservoir, for a slightly compressible liquid flow in dual-porosity systems at constant wellbore pressure.

The transient and boundary-dominated flow periods are examined by means of computer results generated with a finite differences simulator. Analytical expressions of velocity and wellbore rate are presented for the first time in this paper. These equations contain the laminar flow solution as a particular case. A method is proposed to identify the presence of inertial effects by plotting d(log(q))/d(log(t)) against log (t).

The method for area calculation under laminar conditions produces a good approximation for a reservoir under non- laminar flow. However, the presence of inertial effects distort the shape of decline curves resulting in erroneus estimates of wellbore and reservoir parameters by type curve analysis with laminar decline curves.

The utility of the methodology presented in this work is illustrated with synthetic examples.

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