Reservoir Flow Units: A Comparison Between Three Different Models in the Santa Barbara and Pirital Fields, North Monagas Area, Eastern Venezuela Basin

Abstract

Abstract The North Monagas Area presents apparently homogeneous thick sand bodies in the producing section. These sands, some in the order of hundreds of feet, have been until recently considered as single flow units. However, different production scenarios have indicated the presence of distinct flow units with particular petrophysical characteristics within each sand. Several definitions and techniques have been applied to determine flow units. In this study, flow units are defined as sediment intervals that maintain a similar relation between their petrophysical properties such as porosity, permeability, water saturation, pore throat radius, and storage and flow capacity, and that differ from the petrophysical characteristics of the intervals immediately above and below. Three different methodologies were analyzed and compared with the purpose of determining their similarities and divergences. The first method is derived from the sedimentological description of cores, using grain size as the main factor. The second method applies empirical equations based on pore throat radius an its relation to flow capacity, and their use in the determination of petrofacies or rock types, whereas the third method is based on a systematic model which uses the concepts of mean hydraulic radius and flow zone indicators to determine hydraulic units. The definition of flow units allowed a better petrophysical characterization of the field and provided better judgement for the selection of production and injection intervals.