Development of an enhanced model to predict asphaltene stability using the PC-SAFT Equation of State

Abstract

Asphaltene precipitation and subsequent deposition address one of the major flow assurance concerns for oil industries. Modeling of the properties of crude oil systems requires tuning of an appropriate equation of state to the crude oil properties and phase behavior. The experimental evidence found on the mechanisms of asphaltene precipitation and aggregation is in conceptual agreement with the modeling approach for phase stability based on the PC-SAFT Equation of State (EoS). It is proven that the PC-SAFT EoS can provide very accurate predictions of the phase stability of asphaltenes, bubble point of the oil, density of gas and liquid phases, Gas-Oil-Ratio, composition of liberated gas and even asphaltene compositional grading that can induce in extreme cases the formation of tar-mats. In this work, we present an enhanced characterization methodology that is applied to various wells from three different fields in the Middle East region. It was possible to reduce the number of adjustable parameters for asphaltenes and we are still able to get comparable results for the phase stability of asphaltenes as well as other properties mentioned earlier. The new method simplifies process of parameter estimation and reduces its computational time significantly, without compromising the accuracy of predictions. The proposed model has got more physical basis for explaining the phase behavior of asphaltenes in crude oils. Furthermore, advanced optimization strategies have been investigated that can be implemented in the in-house asphaltene phase prediction simulator based on PC-SAFT equation of state developed at The Petroleum Institute.

Date of Award	2012
Original language	American English
Supervisor	Francisco H. Vargas (Supervisor)