Characterization of Multiphase Flow in Shale Oil Reservoirs Considering Multiscale Porous Media by High-Resolution Numerical Simulation

Abstract

Summary Multiphase flow behavior in the complex porous media of lacustrine shale oil is critical to the oil production performance. Shale oil reservoir processes spatial spaces of multiscale porous media. In view of the mesoscopic scale, the fluids flow behaviors of shale oil reservoirs are significantly different from that of tight oil reservoirs and the multimedia flow fluxes in shale have to be reevaluated. Furthermore, upscaling methods from the mesoscopic scale to the macroscopic level as well as coupling methods of multimedia mass transfer have not been adequately established. Based on the multiple media model, such as organic-inorganic matter system and embedded discrete fracture model (DFM), this work proposes a multiscale porous media flow simulation method that is applicable for lacustrine shale oil reservoirs. In the model, various reservoir matrix and flow spaces, such as organic pores, intragranular pores, intergranular pores, and fracture networks composed of bedding fractures and hydraulic fractures, are included. Methods of mass flux conductivity estimations among multiscale media and the relevant upgrading methods are also proposed. Validation of the model is first conducted by the comparison of the oil production performance estimated by the proposed model and a theory solution, and the model is further compared to Gulong shale oil reservoir data to determine its availability in field application. The results show that the proposed simulation model is capable of accurately characterizing the multiphase flow characteristics in multiscale media in shale. It is further demonstrated that the proposed model significantly improves the simulation accuracy over the current nonupscaling models. Field study shows that, based on the accurate characterization of the complex flows in shale oil reservoirs, the research output can provide support for future development of the Gulong shale oil reservoir.