Over last decades, organic geochemistry has been used as a technique for petroleum characterization and production allocation in conventional reservoirs. This work presents the application of geochemistry as a discipline for the study of Vaca Muerta Formation in three producing oil fields in Neuquén Basin. The main objective of the study consisted in the characterisation of produced oils from different levels of Vaca Muerta formation during 12 months of production. A total of 99 fluids corresponding to 18 wells from different landing zones: Kitchen and Organic (Lower and Upper) were sampled every two months and analysed in the laboratory. The methodology is based on the analysis of the oils by gas chromatography as well as determination of physical properties, definition of parameters and geochemical ratios - that may allow the origin and the possible primary and secondary alterations of oils -, multivariate analysis and production allocation. The results obtained allowed to discriminate different productive levels of Vaca Muerta Formation, both vertically and laterally and determine the variation of oil composition over time. Thus, the most appropriate endmembers were selected to perform the production allocation and according to the contribution results, to estimate possible interferences between different production levels at the time of well start-up. These approaches in combination with other studies, would enable the enhancement of vertical and horizontal spacing of unconventional wells.