The hard-core effect on PC-SAFT to model asphaltene precipitation in petroleum reservoir fluids

Abstract

In this work, a hard-core version of the Perturbed Chain-Association Fluid Theory Equation of State (PC-SAFT EoS) is proposed and used to predict upper asphaltene onset pressures (AOPs), bubble points (BPs), and precipitated asphaltene amounts for eighteen real petroleum reservoir fluids around the world. As a result, for the same assumed asphaltene molecular weight (MW) value, this hard-core PC-SAFT model predicts lower AOPs than the other two PC-SAFT versions here tested, including the original version of PC-SAFT. The AOPs and precipitated asphaltene amounts are found to be directly related to the asphaltene MW values used for each PC-SAFT model. The hard-core PC-SAFT model here presented is the PC-SAFT version that requires the lowest asphaltene MWs and predicts the lowest precipitated asphaltene amounts for the eighteen fluids modeled.