DescriptionSimulations of fluid flow in oil/gas shale rocks are challenging in part due to the heterogeneous pore sizes ranging from a few nanometers to a few micrometers. Additionally, the complex fluid-solid interaction occurring physically and chemically must be captured with high resolution. To address these challenges while minimizing computational cost, we present a GPU code that has implemented a many-body dissipative particle dynamics (mDPD) model for multiphase flow in shale. Realistic nano- to micro-pore channels in shale are constructed from 3D high-resolution stack images. In our benchmark tests, the code delivers nearly perfect weak and strong scalings on up to 512 K20X GPUs on Oak Ridge National Laboratory (ORNL) Titan supercomputer. Moreover, single-GPU bench-marks on the DGX-1 (V100/no NVLink), ORNL’s SummitDev (P100/NVLink 1.0) and Summit (V100/NVLink 2.0) suggest that the latest Host-to-Device NVLink can significantly boost overall performance, in addition to the Device-to-Device NVLink.