A Multipoint Multiscale Modeling Method for Solid-Based Thermal Reactive Flow,with Application to the In-Situ Conversion Process

摘要

Thermal-reactive-compositional flow simulation in porous media is essential to model unconventional thermal oil recovery processes for extra-heavy hydrocarbon resources,e.g.,the In-situ Conversion Process (ICP)for oil-shale production.Computational costs can be very high for such a complex system,which may make simulation studies prohibitively time consuming for large field-scale applications on fine grids. On the other hand,significant errors are introduced with the use of coarse-scale models.In this paper,we developed an innovative multipoint multiscale modeling method to effectively capture the fine-scale reaction rates in coarse-scale ICP-simulation models.In our multiscale method,coupled thermal-reactive- compositional flow equations are solved only on the coarse-scale,with the kinetic parameters(frequency factors)calculated based on fine-scale reaction rates.We perform the temperature downscaling by solving the heat diffusion equation in local regions subject to temperature-gradient boundary conditions obtained from a multipoint evaluation on the coarse grid.A multiscale treatment is also developed for the heater well model.Coarse-scale heater well indices are calculated from fine-scale well models using downscaled temperatures.The newly developed multiscale method is applied to realistic cross-sectional ICP-pattern models with a vertical production well and multiple horizontal heater wells operated subject to a time-varying power.It is shown that the multiscale model delivers results that are in close agreement with the fine-scale reference results for all quantities of interest.Despite the fact that the multiscale method is implemented at the simulation-deck level,using the flexible scripting and monitor functionalities of our proprietary simulation package,significant computational improvements are achieved for all cases considered.