(445e) Modeling and Prediction of Asphaltene Precipitation for Two Crude Oil Samples from Kuwaiti Fields Along Production Wells

Two samples of crude oils were collected from the gathering centers for analysis and asphaltene stability tests. Properties such as density, viscosity, asphaltene and SARA analysis were determined in laboratory. One of the crude oil sample was heavy with API Gravity of 20 and asphaltene content of 9.7% while the other oil sample had API gravity of 27.7 and asphaltene content of 1.8%. Asphaltene stability tests by 5 different methods showed both oils were unstable with respect to asphaltene precipitation. A thermodynamic model based on SAFT equation of state was programmed using excel to demonstrate phase behavior of these asphaltenic oils. In addition, a model was developed to predict temperature and pressure profiles along wellbore which was favorably compared with results obtained from professional simulators such as PIPESIM and OLGA. In this modeling heat and mass transfer equations are solved numerically. The temperature drop is calculated from heat loss from the fluid and pressure drop is estimated from friction and hydrostatic pressure drops with the help of Duns and Ros method. By combination of predicted PT profile with asphaltene phase diagram we can show the exact region along the wellbore where aphaltene phase separation occurs.