Characterization of Reservoir BDV-1 (U1-U4) Budare Field, Guarico, Venezuela For the Drilling of Horizontal Wells

Abstract

The low production rates in conventional (vertical) wells have obliged the industry to propose the drilling of horizontal wells in order to improve oil recovery. In Budare Field, we have chosen the reservoir constituted by U1 and U4 sandstones to study the behavior of horizontal wells. To reach our objectives successfully, a detailed sedimentological study has been carried out, which consists of a precise correlation aimed to determine the geometry and distribution of reservoir sand bodies. Our study emphasized Oligo-Miocene oil sands, which correspond to units U2 (lower) and Ul (upper). The lower unit consists of three sandstone levels representing meandering fluvial channel deposits with north-south direction. The upper unit contains four sandstone levels which correspond to less-meandering or, possibly distributary, channels. The direction of these channels changes from NNE-SSW (base) to north-south (top). All sandstone bodies are separated by shale intervals of floodplain environments, which serve as seals for the reservoir rock. The connections between these sandstones were calibrated by using production tests available for the different wells at the reservoir level. The sedimentological model has been validated through the elaboration of structural cross sections. The geological model (sedimentological and structural) together with the production tests have served to choose to a certain degree of precision the prospective sandstone bodies, as well as the exact direction of the horizontal wells to be drilled.