Novel Approach for Rate Transient Analysis of Fractured Wells from Carbonate Reservoirs with Heterogeneous Natural Fractures

[Image: see text] This paper developed a new methodology for rate transient analysis of fractured wells in carbonate reservoirs. Both the heterogeneity and dual-permeability flow behavior are incorporated into the proposed model, and the fractured carbonate reservoir was simulated with a two-zone composite model. In each zone, a traditional dual-porosity model was applied to describe the characteristics of the natural fractures and matrix. With the Laplace transform, we derived the solution of the mathematical model and plotted new type curves for transient rate decline analysis. Then, the flow regimes were divided and analyzed based on the new type curves. The influences of several critical parameters on transient rate response were also examined. A field case was studied further to demonstrate the precision and application of the proposed method. The results show that the new type curves are mainly composed of eight flow stages. The difference in physical properties (k(2,1), η(2,1)) between the two zones significantly impacts the transition and boundary-dominated flow regimes. When the values of k(2,1) and η(2,1) are smaller, the derivative curve of the transition flow stage will move down, and the duration of this stage on the derivative curve is longer, while the duration of the boundary dominant flow stage will decrease. The dimensionless radial radius of the inner zone (r(1D)) can significantly influence the transition flow regime. When r(1D) is larger, the production rate and its derivative curve of the transition flow stage will move up, and the duration of this stage will be longer. The results also show that the proposed methodology can effectively fit the field production data. This method can be applied in well productivity evaluation for fractured carbonate reservoirs.