Critical Parameters in Static and Dynamic Modeling of Tight Fluvial Sandstones

Abstract

Abstract This paper presents an integrated static and dynamic evaluation for selecting an appropriate geostatistical modeling method that best represents the production from a tight, stacked fluvial sandstone reservoir.The critical parameters investigated include sand body geometry, water saturation permeability, and hydraulic fracture properties.This effort involves the construction of several static and dynamic models within a one-square mile section of the field. The study area contains about twenty-four wells with varying productivity or EUR, indicative of the reservoir heterogeneity.Several geological scenarios were developed to characterize facies/sand bodies, and multiple realizations of each scenario were investigated.Reservoir properties including porosity, water saturation and permeability were populated for each realization using sequential Gaussian simulation. The geological scenarios incorporated variations of three widely used facies modeling algorithms: fluvial object, defined object, and sequential indicator simulation.These algorithms have their pros and cons in representing the distribution of reservoir facies.The model constraints, including facies at wellbores, global facies proportion, vertical facies probability, and areal facies probability constructed from well data were held constant between the scenarios, and infill well locations were used to evaluate the static facies prediction. Reservoir dynamic models were used to rank individual scenario performance.The static and dynamic models share the same grid dimensions and no upscaling of reservoir properties was performed.The grid system and the recurrent data (completion, production and pressure histories) for the wells were consolidated in schedule files for input into a reservoir simulator.While there were no attempts to match the historical performance of the wells, boundary conditions and/or constraints derived from field operation were determined and used as production controls for the wells.Average hydraulic fracture properties were assigned to the fracture cells of each well, and gas production under depletion drive was simulated with the flow models thus built.The results were evaluated qualitatively and quantitatively to select the appropriate modeling workflow for constructing the static and dynamic models of the field.