Abstract
Because it is extremely time-consuming to run compositional simulations, people tend to use fewer components, or fewer grid blocks, or both. However, the use of fewer components leads to inaccurate phase behavior while application of fewer grid blocks causes larger numerical dispersions. When the reservoir temperature is lower than 120 °F and pressure is lower than 1500 psia, gas injections, especially when injectants include CO2, may result in four phases: water, oil, gas, and the second non-aqueous liquid. In this paper, a streamline simulator is developed and found to be able to be used to model the four-phase flow for the 9-component injection of 50-50 combination of Prudhoe Bay Gas (PBG) and Natural Gas Liquid (LNG) into a reservoir with 12-component viscous Shrader oil. Results indicate that the streamline simulation is many times faster than finite-difference simulation. In addition, viscous fingering is sharply caught by streamline simulation while the displacement front is very blurry in finite-difference simulation due to high numerical dispersions.
The streamline simulator can be used for gas injection problems with up to four phases.
