Reservoir characterization and representation in simulation models: a pilot area of a carbonate reservoir from the Brazilian pre-salt

Abstract

The success of the decision-making processes related to the development and management of petroleum fields relies on the proper understanding of the reservoir. To do so, practitioners use geological and simulation models to perform in-depth analysis of fluid flow over time to decide on the best production strategy. The process begins with a team of geoscientists and consists in building a conceptual model of the target reservoir. Then, with all the available data, such as 3D seismic data, well logs and cores, the geoscientists use advance reservoir characterization techniques to build a high-resolution (fine-grid) geological model. This includes the structural framework of the reservoir and the spatial distribution of the static rock properties (facies, porosity, permeability, net-to-gross). Then, a team of geoengineers, experts on the integration between geological modeling and reservoir simulation, take on a series of steps to add the dynamic data related to fluid composition and rock-fluid properties into the reservoir model, in addition to upscaling the grid to make it feasible for numerical flow simulation. This multidisciplinary process involves several challenges, such as (1) to represent multiscale heterogeneities in reservoir simulation, (2) upscaling procedures in complex frameworks, mainly fractured reservoirs, (3) to apply uncertainty analysis to study critical parameters, and (4) to study numerical controls to decrease the runtime of numerical simulation. The world-class pre-salt discoveries, the target of this proposal, are amongst the most important over the last decade. They consist of large accumulations of excellent quality, light oil of high commercial value, playing an important role to meet the global demand in a challenging scenario of energy transition. Pre-salt carbonate reservoirs are still particularly difficult to represent in simulation models due to their unique features, heterogeneities and size, when compared to the post-salt discoveries that energy companies have come to master. This 1-year postdoctoral project, which is part of the engineering research center EPIC (FAPESP/EQUINOR), intends to integrate the research conducted at "RL1 - Production optimization using reservoir simulation models" and "RL3 - Geological characterization and modeling of a carbonate reservoir from the Brazilian pre-salt". The main objectives are: (1) to build reservoir simulation models of a pilot area from a pre-salt carbonate reservoir, including uncertainties, based on the static geological model from RL3, (2) test different grid sizes (model fidelities) and (3) estimate the impact of uncertainties in production forecast. (AU)