Resumen del autor, extraído del trabajo. The area of interest is the Tia Juana field, in the area of the Project F7, Western Venezuela. The reservoir in the F7 area is the lower part of the Lagunillas Formation (Miocene), the members that we have studied for this project included the Lagunillas Inferior and the Ojeda members. The first one is the lowermost part of the formation and overlays the first transgressive sand (Santa Barbara) and shales of the Miocene transgressive system track called La Rosa Formation. This places the Lagunillas Inferior Member as a highstand, prograding sandy parasequences, with gentle 4th order transgressive/regressive cycles overlying it as the Ojeda Member, at the top of which we found what is called the "hard-bed" of the area and we suppose it represents a flooding surface on the paralic plains that was exposed later to subaerial weathering; this bed is an excellent correlation level in the area.