Modeling Asphaltene Phase Behavior: Comparison of Methods for Flow Assurance Studies

Asphaltenes are the heaviest and most highly polarizable and polydisperse petroleum fractions in crude oils. The solubility of the asphaltenes in crude oils is usually affected by the reduction of pressure, temperature, and/or oil composition change as a result of commingling with other crude oils or gas injection. This may lead to asphaltene precipitation and deposition, decline in permeability, blockage of well and surface facilities, and finally, production decrease or termination, which has a substantial economical impact. Therefore, the ability to understand and predict asphaltene phase behavior is essential for both up- and downstream processing, so that appropriate strategies can be implemented for prevention and remediation. In our study, we present the capability and advances of the equations of state approach by applying the cubic-plus-association (CPA) and the perturbed-chain statistical associating fluid theory (PC-SAFT) equation to model asphaltene stability in live oils and compare the predictions to the various types of measured asphaltene precipitation data over wide ranges of temperature and pressure.