Abstract This paper develops a new conceptual liquid-hydrocarbons migration model for practical application in organic-rich mudstone reservoirs. The method uses a combination of well log formation evaluation data, micro-resistivity image logs, nuclear magnetic resonance, and geochemical measurements obtained from either drill-cuttings or core data. In the method proposed in this paper, organic matter (OM) geochemical indicators from organic petrography (thin sections), vitrinite reflectance, TOC from Leco analyzer, Rock-Eval pyrolysis including S1, S2, and Tmax are integrated with triple-combo and NMR logs so that both lean and organic-rich intervals can be identified. The addition of natural fracture intensity to the interpretation package makes the methodology quite unique. After applying cut-offs for each individual parameter, two types of migrations are identified that could take place in these source-rock reservoirs: primary and secondary migration. The model is applied in a wildcat vertical well that penetrated several stacked organic-rich mudstones. The formation gross thickness of the evaluated section is around of 2800 ft-TVD divided into six main formations composed mainly by siliciclastic minerals with a moderate carbonate content, and low presence of clay minerals. The source-rock reservoirs penetrated by the well can be sub-divided into (1) naturally-fractured, (2) tight and (3) hybrid reservoirs. Reservoirs in sub-division (1) are very important because they might be able to produce oil without the need of hydraulic fracturing. Reservoirs in sub-division (2) have natural fractures but their scale is very small to allow any oil production. Consequently, they must always be hydraulically fractured. Reservoirs in sub-division (3) might or might not need hydraulic fracturing. Intervals with high organic carbon content, S1, oil saturation index, and geochemical index but low natural fracture intensity indicate tight reservoirs, and they likely correspond to the hydrocarbon source that charged the juxtaposed naturally fractured or hybrid reservoirs. On the other hand, several intervals that present poor TOC, are highly brittle and naturally-fractured, and are connected with tight organic-rich intervals. Thus, the potential of these naturally fractured intervals to produce oil is quite significant. The novelty of the method developed in this paper permits analyzing primary and secondary migration in the source rock. The method further permits identifying the type of reservoir (naturally fractured, tight and/or hybrid) penetrated by the exploratory wells. This allows ranking the most prospective intervals as well as optimum landing zones for future horizontal or geosteered wells to be drilled in neighboring areas.