Predicting Asphaltene Precipitation Using Modified Flory-Huggins Theory; Case Study of an Iranian Oil Reservoir

Asphaltene precipitation is one of the crucial problems in oil industry. any changes in pressure, temperature, composition may causes asphaltene precipitation. The high cost of remediating asphaltene deposition in crude oil production and processing, has necessitated the development of the methods for determining the stability of asphaltenes in crude oils and also predicting the asphaltene precipitation during different conditions. Different models are presented for prediction of asphaltene precipitation. Available thermodynamic models for asphaltene precipitation prediction are essentially divided into three groups. In this study a thermodynamic model based on molecular thermodynamic and solubility model is presented which able to predict asphaltene precipitation in a wide range of pressure (from reservoir pressure to atmospheric pressure) and temperature. This model is a modification on Flory-Huggins solution theory with a correctly tuned equation of state for calculation of solubility parameter of liquid oil. Also, This study concerns with experimental investigations of asphaltene precipitation at reservoir conditions of a crude sample from an Iranian oil reservoir during pressure depletion. High pressure high temperature set up and filtration method was used to quantify amount of precipitated asphaltene at different pressures. The experimental results have been used to develop the new asphaltene precipitation model. Comparing the results of the model with experimental data shows an excellent match spiciaaly at reservoir conditions.