A Compositional Reservoir Simulation and Experimental Investigation of Asphaltene Onset Pressure

Abstract

Asphaltene precipitation is one of the most common problems in many reservoirs and may lead to many safeties operational issues which affects on oil recovery; therefore, identifying start of asphaltene activation is known as a key parameter to control production efficiency. This study includes predicting onset pressure with Multiphase Flash test and compare its result with experimental data generated by Asphaltene Static Apparatus. Safety pressure was obtained by performing Multiphase Flash test for each component. In order to prevent adsorption, mechanical entrapment, and blockage, reservoir pressure must be higher than this safety pressure. SARA test is widely used to identify the fraction of crude oil that affect the asphaltene stability. IP143 standard test was used to measure precipitated asphaltene. Natural depletion test was designed at four steps, including 4400, 3000, 1550, and 1020 Psia and reservoir temperature is 205°F. It was seen that with decreasing pressure from reservoir pressure to saturation pressure asphaltene precipitation from PVT cell was increased and at pressures below saturation pressure with pressure reduction, asphaltene precipitations was decreased. Also it was concluded that above saturation pressure solubility model is dominant and below saturation pressure colloidal model is dominant. The results of IP143 show that initial content of asphaltene are 12.8%. SARA test result shows this kind of fluid located at unstable asphaltene precipitation region. Comparison of safety pressure between Multiphase Flash test and experimental data are investigated and discussed. Onset pressure of 18000 Pisa was obtained from Multiphase Flash test, which is in good agreement with experimental result.

Keywords:

• asphaltene
• multiphase flash test
• onset pressure
• precipitation
• safety pressure