Naturally fractured reservoirs (NFRs) are a challenge for the petroleum industry. Many newly discovered reservoirs are fractured. In NFRs most of the oil is stored in the matrix, while fluid transport takes place in the fractures. Dealing with NFRs means to manage a large amount of uncertainty. To reduce it, this work proposes numerical investigations of matrix depletion processes on different scales. These are (1) single matrix block, (2) one column, (3) single well, (4) cross section and (5) full field models. The common approach for simulating NFRs is using the dual continuum concept, which is applied to the modeling steps (2) to (5). For model type (1), a matrix block and the surrounding fractures are discretized. The 1D one column model is comprised of a dual continuum grid cell stack. Together with the single matrix block model it is used to analyze the influence of various reservoir parameters on recovery. Single well models allow to investigate near wellbore flow. The goal of this model is to estimate future well rates. 2D cross section models are suited for demonstrating displacement processes. The size of model types (1) to (4) is in the range of a few ten up to 20,000 grid blocks. Thus sensitivities of reservoir properties on recovery can be run. Not so for the full field model, typically having a size of 100,000 up to 1,000,000 grid blocks. The knowledge gained from models (1) to (4) is applied to the full field models to minimize the number of full field runs.