Lower Reineche hydrocarbon-bearing limestones is subdivided into four different layers the first three ones (LRN1, LRN2, LRN3) belong to nummulite-rich unit and represent the main reservoir however the fourth layer (LRLs), which corresponds to an argillaceous limestones, is not considered as reservoir layer although its fair porosities. The sedimentological study based on CL description, USB, TS, and SEM analyses allowed the identification of eight facies. In the cored wells, the specified facies coupled to the FMI interpretation are used in order to recognize the specific response of each facies. Then the comparison of the FMI logs of the non-cored wells with those of the cored ones assists the prediction regarding facies and reservoir characteristics and helps to fill interpretive gaps when comprehensive formation evaluation data is not available. The CMR Logs show generally one modal T2 distribution illustrating the existence of only one fluid type except the LRN2 showing bimodal T2 distribution. In addition, this T2 signal is wide expressing a large pore size distribution (micro- to macroporosities). The sedimentological study proved the existence of matrix microporosity, an intergranular porosity between Nummulite tests and an intragranular porosity within Nummulites which is effective only when affected by microfractures (meso- to macroporosities). For Lower Reineche limestones, integration of sedimentological, RCA, FMI and CMR studies specified the different facies in addition to the porosity and permeability distribution in the reservoir. Nummulit biofabric and early diagenesis are the main factors that control the petrophysical characteristics of the Nummulit bearing limestones. The understanding of the heterogeneity and the distribution of the porosity and the permeability in this area is important for the reservoir modeling and the hydrocarbon (gas mainly) saturation.

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