In the Chañares Herrados oilfield, located in the Northwest of the Cuyana basin, the Victor Oscuro member of the Río Blanco formation, presents reservoirs of distal lacustrine environment with influence pyroclastic and high clay content. Some sections of this member are mineralized with oil and are characterized by low resistivity, however, they are often good reservoirs and produce with low water cut in many wells of the field.Petrophysical characterization of "Low Resistivity Pay" reservoirs presents a challenge for interpretation since their correct determination is difficult and always tends to give a high value of water saturation, which masks the real saturation of oil.In this study the behavior of thin lacustrine reservoirs with low resistivity will be described. Micro porosity plays a key role; together with the presence of water with high capillarity (high capillary bound water).The Victor Oscuro lacustrine deposits, mainly composed of siltstones, claystones and pyroclastic sediments with microporosity, give low resistivity readings in the oil reservoirs. These micro pores at the same time, increase the content of irreducible water which causes low water production rates. The permeability in such reservoirs ranges from 0.005 to 0.6mD and average porosities are 19% (between 13 to 23%).Due to the complex lithology of these reservoirs the presence of claystones with high CEC (cationic exchange capacity) is very common in this type of deposits. The rock is strongly water wet; consequently, the result is a high percentage of irreducible water saturation and transition zones capable of producing moderate water, despite the high water saturation interpretation.