Evidences of the existence of a gas-water palaeo-contact in the Pilmatué Member of Agrio Formation - El Mangrullo and Rincón del Mangrullo fields Since its discovery in 2013, the Pilmatué Member of Agrio Formation became the main gas reservoir of El Mangrullo field. It is composed by sandstones intercalated with mudstone layers, defining a set of prograding sequences. Thanks to the advance in knowledge during its productive development (which continues up to the present) it is known that there is a wide zone of residual gas between the accumulation and the zone with 100% Sw, located mainly in the neighboring block of Rincón del Mangrullo (RDM). To the moment, this had been confirmed only with wells, without a contribution of seismic data. From this observation, the seismic cubes of RDM and El Mangrullo - Las Tacanas (EMLTN) were studied with the aim of detecting some feature related with the mentioned model, and thus be able to delimit itareally. The analysis carried out revealed the existence of a sub-horizontal seismic event visible in a large part of RDM cube as well as in the southeast part of EMLTN 3D. The signal features (amplitude, response phase) together with the well data (Sw curves) allowed to interpret it as a gas-water palaeocontact. In addition, marked variations in the amplitude of other nearby reflectors were detected, that would also act as indicators of fluid change in the reservoir. The conjunction between the wells information and what was provided by seismic allowed to validate the accumulation model of Pilmatué Member, contributing to its better development. This work also presents a methodology that could be applied to the study of other analogous reservoirs.