The Oritupano block is located on the southern part of the Maturin Sub-basin, in the Eastern Foredeep Basin of Venezuela. In this area, the Oficina Fm., with ages ranging from early to middle Miocene, consists of 2100 feet of sandstones interbedded with shales deposited in a ramp setting. The objective of this study is to characterize the B Sands of the Oficina Fm., integrating well logs and 3D seismic data. Seismic and well data indicate that B Sands, with average thickness in the study area of 110 feet, are Lowstand and Transgressive System Tracks (LST-TST) deposits bounded by a Sequence Boundary at the base (SB B) and a Maximum Flooding Surface at the top (MFS B). The seismic expression of these surfaces is, respectively, a negative and a positive polarity reflection interface (SEG polarity standard). Horizon slices created from the MFS B show persistent NE trending geological features through a time interval of 20 milliseconds below the MFS B. Synthetic seismograms indicate that this time interval includes most of the B Sands incised valley deposits. This time window was used to construct a seven-classes seismic facies map. Seismic facies analysis assesses the variation in seismic wavelet shape over an interval of interest. Cross correlation between seismic facies and the petrophysical properties of 40 wells indicates a close relationship between seismic facies and net thickness for the B Sands interval. An integrated net thickness map of the studied interval was obtained through the following steps: (1) Well grouping through net thickness vs. seismic facies crossplot. (2) Computation of the net thickness average per seismic facies class. (3) Generation of a net thickness map assigning the net thickness average value to each seismic facies class. (4) Flexing of the map obtained in the previous step to the well net thickness values. This integrated net thickness map allows: the prediction of net thickness in non-drilled areas, the estimation of reserves, and a reliable input for simulation studies.