Stochastic Modeling of Reservoir Architecture for Field Management

Summary This paper outlines a probabilistic geologic modeling system developed to describe and characterize heterogeneous fluvio-deltaic sandstone reservoirs in the San Diego area, Orinoco belt, eastern Venezuela. The model uses field, well, and laboratory data to simulate synthetic stratigraphic sections in different directions and to delineate the geometry, continuity, and anisotropy of sand bodies and the regional distribution of internal reservoir properties (porosity, permeability, and hydrocarbon saturation). From a stochastic viewpoint, the model introduces the following improvements: (1) a Poisson process to predict the occurrence of sedimentary sand bodies in the stratigraphic sections, (2) facies proportion curves to condition the occurrence of sand bodies on the depositional environments, (3) Latin hypercube sampling (LHS) as a more precise sampling method in simulation, and (4) a geometric computer modeling technique (QUADTREES) to calculate the reservoir properties and to delineate complex geometries and effective drainage areas. These techniques are illustrated by use of field data from a pilot development in the San Diego area.