Parametric Study of the Influence of GOR and CO₂ Content on the Simulation of a Pre-Salt Field Configuration

A distinct characteristic of reservoir fluids in different Brazilian pre-salt fields is the high Gas-Oil- Ratio (GOR) and high content of CO₂ in the associated gas. In particular, the presence of CO₂ in significant amounts is known to have a strong influence on the thermophysical properties and phase equilibria of the oil mixtures. Due to the strategy of re-injection of CO₂-rich streams for EOR purposes, these aspects can be even more pronounced in the production fluids in future scenarios. In the present work, a parametric study is performed to investigate the influence of both CO₂ molar content and GOR, in a controlled manner, on the simulations of a pre-salt field configuration for various operating conditions. PVT look-up tables were used with a commercial multiphase flow simulator.

First, the thermodynamic modelling of a 20% molar CO₂ pre-salt oil was performed, along with well characterized CO₂-live oil mixtures taken from the literature, in order to generate PVT look-up tables. They were used to successfully reproduce field data and assess the validity of multiphase flow simulation results from a commercial software. For the CO₂-rich live oil mixtures from the literature, a parametric study was performed in which the CO₂ molar content ranged from 20% to 50% with 300-600 Sm³/Sm³ of GOR. Simulation results of temperature, total pressure drop, gas volume fraction and gas- liquid density ratio are presented and compared.